demonstrating compliance with vehicle CO2 standards while
the fuel consumption result will be used for demonstrating compliance
with the fuel consumption standards.
    The vehicle manufacturer will be responsible for entering
aerodynamic properties of the vehicle, the weight reduction, tire
properties, idle reduction systems, and vehicle speed limiting systems.
For GEM inputs relating to weight reduction and aerodynamics, the
agencies are proposing the use of lookup tables based on typical
performance levels across the industry. These lookup tables do not have
data directly related to CO2, but rather provide the
appropriate coefficients for the model to assess CO2- and
fuel consumption-related performance. The agencies will enter the
appropriate engine map reflecting use of a certified engine in the
truck (and will enter the same value even if an engine family is
certified to the temporary percent reduction alternative standard, in
order to evaluate vehicle performance independently of engine
performance.) We believe this approach reduces the testing burden
placed upon manufacturers, yet adequately assesses improvements
associated with select technologies. The model will be publicly
available and will be found on EPA's Web site.
    The agency reserves the right to independently evaluate the inputs
to the model via Administrator testing to validate those model inputs.
The agency also reserves the right to evaluate vehicle performance
using the inputs to the model provided by the manufacturer to confirm
the performance of the system using GEM. This could include generating
emissions results using the GEM and the inputs as provided by the
manufacturer based on the agency's own runs. This could also include
conducting comparable testing to verify the inputs provided by the
manufacturer. In the event of such testing or evaluation, the
Administrator's results become the official certification results. The
exception being that the manufacturer may continue to use their data as
initially submitted, provided it represents a worst-case condition over
the Administrator's results.
    To better facilitate the entry of only the appropriate parameters,
the agencies will provide a graphical user interface in the model for
entering data specific to each vehicle. This graphical user interface
allows the end user to avoid interacting directly with the model and
any associated coding. It is expected that this template will be
submitted to EPA as part of the certification process for each
certified vehicle configuration.
    For certification, the model will exercise the vehicle over three
test cycles; one transient and two steady-state. For the transient
test, we are proposing to use the heavy-heavy-duty diesel truck (HHDDT)
transient test cycle, which was developed by the California Air
Resources Board and West Virginia University to evaluate heavy-duty
vehicles. The transient mode simulates urban, start-stop driving,
featuring 1.8 stops per mile over the 2.9 mile duration. The two steady
state test points are reflective of the tendency for some of these
vehicles to operate for extended periods at highway speeds. Based on
data from the EPA's MOVES database, and common highway speed limits, we
are proposing these two points to be 55 and 65 mph.
    The model will predict the total emissions results from each
segment using the unique properties entered for each vehicle. These
results are then normalized to the payload and distance covered, so as
to yield a gram/ton-mile result, as well as a fuel consumption (gal/
1,000 ton-mile) result for each test cycle. As with engine and vehicle
testing, certification will be based on a parent rating for the test
group, representing the worst-case fuel consumption and CO2
emissions. However, vehicle manufacturers will also have the
opportunity to model sub-configurations to determine any benefits that
are available on only a select number of vehicles within a test group.
    The results from all three tests are then combined using weighting
factors, which reflect typical usage patterns. The typical usage
characteristics of Class 7 and 8 tractors with day cabs differ
significantly from Class 8 tractors with sleeper cabs. The trucks with
day cabs tend to operate in more urban areas, have a limited travel
range, and tend to return to a common depot at the end of each shift.
Class 8 sleeper cabs, however, are typically used for long distance
trips which consist of mostly highway driving in an effort to cover the
highest mileage in the shortest time. For these reasons, we propose
that the cycles are weighted differently for these two groups of
vehicles. For Class 7 and 8 trucks with day cabs, we propose weights of
64%, 17%, and 19% (65 mph, 55 mph, and transient, resp.). For Class 8
with sleeper cabs, the high speed cruise tendency results in proposed
weights of 86%, 9%, and 5% (65 mph, 55 mph, and transient,
respectively). These final, weighted emission results are compared to
the emission standard to assess compliance.
Durability Testing
    As with engine certification, a manufacturer must provide evidence
of compliance through the regulatory useful life of the vehicle.
Factors influencing vehicle-level GHG performance over the life of the
vehicle fall into two basic categories: Vehicle attributes and
maintenance items. Each category merits different treatment from the
perspective of assessing useful life compliance, as each has varying
degrees of manufacturer versus owner/operator responsibility.
    The category of vehicle attributes generally refers to aerodynamic
features, such as fairings, side-skirts, air dams, air foils, etc,
which are installed by the manufacturer to reduce aerodynamic drag on
the vehicle. These features have a significant impact on GHG emissions
and their emission reduction properties are assessed early in the
useful life (at the time of certification). These features are expected
to last the full life of the vehicle without becoming detached,
cracked/broken, misaligned, or otherwise not in the original state. In
the absence of the aforementioned failure modes, the performance of
these features is not expected to degrade over time and the benefit to
reducing GHG emissions is expected to last for the life of the vehicle
with no special maintenance requirements. To assess useful life
compliance, we recommend a design-based approach which would ensure
that the manufacturer has robustly designed these features so they can
reasonably be expected to last the useful life of the vehicle.
    The category of maintenance items refers to items that are
replaced, renewed, cleaned, inspected, or otherwise addressed in the
preventative maintenance schedule specified by the

vehicle manufacturer. Items that have a direct influence on GHG
emissions are primarily lubricants. Synthetic engine oil may be used by
vehicle manufacturers to reduce the GHG emissions of their vehicles.
Manufacturers may specify that these fluids be changed throughout the
useful life of the vehicle. If this is the case, the manufacturer
should have a reasonable basis that the owner/operator will use fluids
having the same properties. This may be accomplished by requiring (in
service documentation, labeling, etc) that only these fluids can be
used as replacements.
    If the vehicle remains in its original certified condition
throughout its useful life, it is not believed that GHG emissions would
increase as a result of service accumulation. This is based on the
assumption that as components wear, the rolling resistance due to
friction is likely to stay the same or decrease. With all other
components remaining equal (tires, aerodynamics, etc), the overall drag
force would stay the same or decrease, thus not significantly changing
GHG emissions at the end of useful life. It is important to remember
however, that this vehicle assessment does not take into account any
engine-related wear affects, which may in fact increase GHG emissions
over time.
    For the reasons explained above, we believe that for the first
phase of this program, it is most important to ensure that the vehicle
remain in its certified configuration throughout the useful life. This
can most effectively be accomplished through engineering analysis and
specific maintenance instructions provided by the vehicle manufacturer.
The vehicle manufacturer would be primarily responsible for providing
engineering analysis demonstrating that vehicle attributes will last
for the full life of the vehicle. In addition they will be required to
submit the recommended maintenance schedule (and other service related
documentation), showing that fluids meeting original equipment
properties are required as replacements.
(ii) EPA's Air Conditioning Leakage Standards
    Heavy-duty vehicle air conditioning systems contribute to GHG
emissions in two ways. First, operation of the air conditioning unit
places an accessory load on the engine, which increases fuel
consumption. Second, most modern refrigerants are HFC-based, which have
significant global warming potential (GWP = 1430). For heavy-duty
vehicles, the load added by the air conditioning system is
comparatively small compared to other power requirements of the
vehicle. Therefore, we are not targeting any GHG reduction due to
decreased air conditioning usage or higher efficiency A/C units for
this proposal. However, refrigerant leakage, even in very small
quantities, can have significant adverse effects on GHG emissions.
    Refrigerant leakage is a concern for heavy-duty vehicles, similar
to light-duty vehicles. To address this, EPA is proposing a design-
based standard for reducing refrigerant leakage from heavy-duty
vehicles. This standard is based off using the best practices for
material selection and interface sealing, as outlined in SAE
publication J2727. Based on design criteria in this publication, a
leakage ``score'' can be assessed and an estimated annual leak rate can
be made for the A/C system based on the refrigerant capacity.
    At the time of certification, manufacturers would be required to
outline the design of their system, including specifying materials and
construction methods. They will also need to supply the leakage score
developed using SAE J2727 and the refrigerant volume of their system to
determine the leakage rate per year. If the certifying manufacturer
does not complete installation of the air conditioning unit, detailed
instructions must be provided to the final installer which ensures that
the A/C system is assembled to meet the low-leakage standards. These
instructions will also need to be provided at the time of
certification, and manufacturers must retain all records relating to
auditing of the final assembler.
(c) In-Use Standards
    As previously addressed, the drive-cycle dependence of
CO2 emissions makes NTE-based in-use testing impractical. In
addition, we believe the reporting of CO2 data from the
criteria pollutant in-use testing program will be helpful in future
rulemaking efforts. For these reasons, we are not proposing an NTE-
based in-use testing program for Class 7 and 8 combination tractors
during this proposal.
    In the absence of NTE-based in-use testing, provisions are
necessary for verifying that production vehicles are in the certified
configuration, and remain so throughout the useful life. Perhaps the
easiest method for doing this is to verify the presence of installed
emission-related components. This would basically consist of a vehicle
audit against what is claimed in the certification application. This
includes verifying the presence of aerodynamic components, such as
fairings, side-skirts, and gap-reducers. In addition, the presence of
idle-reduction and speed limiting devices would be verified. The
presence of LRR tires could be verified at the point of initial sale;
however verification at other points throughout the useful life would
be non-enforceable for the reasons mentioned previously.
    The category of wear items primarily relates to tires. It is
expected that vehicle manufacturers will equip their trucks with LRR
tires, as they may provide a substantial reduction in GHG emissions.
The tire replacement intervals for this class of vehicle is normally in
the range of 50,000 to 100,000 miles, which means the owner/operator
will be replacing the tires at several points within the useful life of
the vehicle. We believe that as LRR tires become more common on new
equipment, the aftermarket prices of these tires will also decrease.
Along with decreasing tire prices, the fuel savings realized through
use of LRR tires will ideally provide enough incentive for owner/
operators to continue purchasing these tires. The inventory modeling in
this proposal reflects the continued use of LRR tires through the life
of the vehicle. We seek comment on this and all aspects of our
inventory modeling.
(2) Proposed Enforcement Provisions
    As identified above, a significant amount of vehicle-level GHG
reduction is anticipated to come from the use of components
specifically designed to reduce GHG emissions. Examples of such
components include LRR tires, aerodynamic fairings, idle reduction
systems, and vehicle speed limiters. At the time of certification,
vehicle manufacturers will specify which components will be on their
vehicle when introduced into commerce. Based on this list of components
reported to EPA the GHG performance of the vehicle will be assessed,
typically through modeling, and a certificate of conformity may be
issued. As described in the in-use testing section, it is important to
have the ability to determine if the vehicle is in the certified
configuration both at the time of sale, as well as at any point within
the useful life.
    Perhaps the most practical and basic method of verifying that a
vehicle is in its certified configuration is through a vehicle
emissions control information label, similar to that used for engines
and light-duty vehicles. This label would list identifying features of
the vehicle, including model year, vehicle model, certified engine
family, vehicle manufacturer, test group, and GHG emissions category.
In addition, this label would list emission-related

components that an inspector could reference in the event of a field
inspection. Possible examples may include LRR (for LRR tires), ARF
(aerodynamic roof fairing), and ARM (aerodynamic rearview mirrors).
With this information, inspectors could verify the presence and
condition of attributes listed as part of the certified configuration.
    Similarly, on current emission control information labels,
manufacturers list abbreviations, which are defined in SAE J1930, for
each emission control device. Examples include three-way catalyst
(TWC), electronic control (EC), and heated oxygen sensor
(HO2S). Unfortunately we are not aware of a similar,
existing list of vehicle emission control devices and features likely
to be used on heavy-duty vehicles. At this point, it is also difficult
to develop such a list due to the wide array of devices and features
vehicle manufacturers may use in the future. Therefore, we are
currently seeking comment on how to best define a list of emission
control devices and features for use in this vehicle GHG certification
label.
    At the time of certification, manufacturers will be required to
submit an example of their vehicle emission control label such that EPA
can verify that all critical elements are present. Such elements
include the vehicle family/test group name, emission control system
identifiers described above, regulatory sub-category of the vehicle,
and Family Emission Limits to which the vehicle is certified to. In
addition to the label, manufacturers will also need to describe where
the unique vehicle identification number and date of production can be
found on the vehicle.
(3) Other Certification Provisions
(a) Warranty
    Section 207 of the CAA requires manufacturers to warrant their
products to be free from defects that would otherwise cause non-
compliance with emission standards. In addition, this warranty must
ensure that the vehicle remains in this configuration throughout its
useful life. For purposes of this regulation, vehicle manufacturers
must warrant all components installed which act to reduce
CO2 emissions at the time of initial sale. This includes all
aerodynamic features, tires, idle reduction systems, speed limiting
system, and other equipment added to reduce CO2 emissions.
In addition, the manufacturer must ensure these components and systems
remain functional for the useful life of the vehicle. The exception
being tires, which are only required to be warranted for the first life
of the tires (vehicle manufacturers are not expected to cover
replacement tires). For aerodynamic features, such as fairings or side-
skirts, the manufacturer must warrant against failures which are not
the result operator damage. However, these components should be
designed to withstand possible damage from normal driving, which may
include stone impingement and other minor impact with small debris.
    The vehicle manufacturer is also required to warrant the A/C system
for the useful life of the vehicle against design or manufacturing
defects causing refrigerant leakage in excess of the standard.
    At the time of certification, manufacturers must supply a copy of
the warranty statement that will be supplied to the end customer. This
document should outline what is covered under the GHG emissions related
warranty as well as the length of coverage. Customers must also have
clear access to the terms of the warranty, the repair network, and the
process for obtaining warranty service.
(b) Maintenance
    Vehicle manufacturers are required to outline maintenance schedules
that ensure their product will remain in compliance with emission
standards throughout the useful life of the vehicle. For heavy-duty
vehicles, such maintenance may include fluid/lubricant service, fairing
adjustments, or service to the GHG emission control system. This
schedule is required to be submitted as part of the application for
certification. Maintenance that is deemed to be critical to ensuring
compliance with emission standards is classified as ``critical
emission-related maintenance.'' Generally, manufacturers are
discouraged from specifying that critical emission-related maintenance
is needed within the regulatory useful life of the engine. However, if
such maintenance is unavoidable, manufacturers must have a reasonable
basis for ensuring it is performed at the correct time. This may be
demonstrated through several methods including survey data indicating
that at least 80% of engines receive the required maintenance in-use or
manufacturers may provide the maintenance at no charge to the user.
(c) Certification Fees
    Similar to engine certification, the agency will assess
certification fees for heavy-duty vehicles. The proceeds from these
fees are used to fund the compliance and certification activities
related to GHG regulation for this regulatory category. In addition to
the certification process, other activities funded by certification
fees include EPA-administered in-use testing, selective enforcement
audits, and confirmatory testing. At this point, the exact costs
associated with the heavy-duty vehicle GHG compliance are not well
known. EPA will assess its compliance program associated with this
proposal and assess the appropriate level of fees. We anticipate that
fees will be applied based on test groups, following the light-duty
vehicle approach.
(d) Requirements For Conducting Aerodynamic Assessment Using Allowed
Methods
    The requirements for conducting aerodynamic assessment using
allowed methods includes two key components: Adherence to a minimum set
of standardized criteria for each allowed method and submittal of
aerodynamic values and supporting information on an annual basis for
the purposes of certifying vehicles to a particular aerodynamic bin as
discussed in the Section II.
    First, we are proposing requirements for conducting each of the
allowed aerodynamic assessment methods. We will cite approved and
published standards and practices, where feasible, but will attempt to
propose criteria where none exists or where more current research
indicates otherwise. We are requesting comment on the proposed
requirements for each allowed method, standards and practices that
should be used, and any unique criteria that we are proposing. A
description of the requirements for each method is discussed later in
this section. The manufacturer would be required to provide information
showing that they meet these requirements and attest to the accuracy of
the information provided.
    Second, to ensure continued compliance, manufacturers would be
required to provide a minimum set of information on an annual basis at
certification time (1) to support continued use of an aerodynamic
assessment method and (2) to assign an aerodynamic value based on the
applicable aerodynamic bins. The information supplied to the agencies
should be based on an approved aerodynamic assessment method and adhere
to the requirements for conducting aerodynamic assessment mentioned
above.
    Regardless of the method, all testing should be performed with a
tractor-trailer combination to mimic real world

usage. Accordingly, it is important to match the type of tractor with
the correct trailer. Although, as discussed elsewhere in this proposal,
the correct tractor-trailer combination is not always present or
tractor-only operation may occur, the majority of operation in the real
world involves correctly matched tractor-trailer combinations and we
will attempt to reflect that here. Therefore, the following guidelines
should be used when performing an aerodynamic assessment:
     For a Class 7 and 8 tractor truck with a low roof, a
standard flatbed trailer must be used;
     For a Class 7 and 8 tractor truck with a mid roof, a
standard tanker trailer must be used;
     For a Class 7 and 8 tractor truck with a high roof, a
standard box trailer must be used.
    The definitions of each standard trailer are proposed in Sec.
1037.501(g). This ensures consistency and continuity in the aerodynamic
assessments, and maintains the overlap with real world operation.
Standardized Criteria for Aerodynamic Assessment Methods
(i) Coastdown Procedure Requirements
    For coastdown testing, the test runs should be conducted in a
manner consistent with SAE J2263 with additional modifications as
described in the 40 CFR part 1066, subpart C, and in Chapter 3 of the
draft RIA using the mixed model analysis method. The agencies seek
comment on the use of these protocols and the modifications that are
described.
    Since the coastdown procedure is the primary aerodynamic assessment
method, the manufacturer would be required to conduct the coastdown
procedure according to the requirements in this proposal and supply the
following to the agency for approval:
     Facility information: Name and location, description and/
or background/history, equipment and capability, track and facility
elevation, and track size/length;
     Test conditions for each test result including date and
time, wind speed and direction, ambient temperature and humidity,
vehicle speed, driving distance, manufacturer name, test vehicle/model
type, model year, applicable model engine family, tire type and rolling
resistance, test weight and driver name(s) and/or ID(s);
     Average Cd result as calculated in 40 CFR 1037.520(b) from
valid tests including, at a minimum, ten valid test results, with no
maximum number, standard deviation, calculated error and error bands,
and total number of tests, including number of voided or invalid tests.
(ii) Wind Tunnel Testing Requirements
    Wind tunnel testing would conform to the following procedures and
modifications, where applicable, including:
     SAE J1252, ``SAE WIND TUNNEL TEST PROCEDURE FOR TRUCKS AND
BUSES'' (July 1981) except that article 5.2 that specifies a minimum
Reynolds number of 0.7 x 10\6\ is not included and is superseded, for
the purposes of this rulemaking, by a minimum Reynolds number of 1.0 x
10\6\ and, for reduced-scale wind tunnel testing, a one-eighth (\1/
8\th) or larger scale model of a heavy-duty tractor and trailer must be
used and of sufficient design to simulate airflow through the radiator
inlet grill;
     J1594, ``VEHICLE AERODYNAMICS TERMINOLOGY'' (December
1994); and
     J2071, ``AERODYNAMIC TESTING OF ROAD VEHICLES--OPEN THROAT
WIND TUNNEL ADJUSTMENT'' (June 1994).
    In addition, the wind tunnel used for aerodynamic assessment would
be a recognized facility by the Subsonic Aerodynamic Testing
Association. The agencies seek comment on the use of these protocols
and the modifications described and the need for membership in this
testing association.
    For wind tunnel testing, we are proposing that manufacturers
perform wind tunnel testing and the coastdown procedure, according to
the requirements proposed in this notice, on the same tractor model and
provide the results for both methods. The wind tunnel tests should be
conducted at a zero yaw angle and, if so equipped, utilizing the
moving/rolling floor (i.e., the moving/rolling floor should be on
during the test as opposed to static) for comparison to the coastdown
procedure, which corrects to a zero yaw angle for the oncoming wind.
The manufacturer would be required to supply the following:
     Facility information: Name and location, description and
background/history, layout, wind tunnel type, diagram of wind tunnel
layout, structural and material construction;
     Wind tunnel design details: Corner turning vane type and
material, air settling, mesh screen specification, air straightening
method, tunnel volume, surface area, average duct area, and circuit
length;
     Wind tunnel flow quality: Temperature control and
uniformity, airflow quality, minimum airflow velocity, flow uniformity,
angularity and stability, static pressure variation, turbulence
intensity, airflow acceleration and deceleration times, test duration
flow quality, and overall airflow quality achievement;
     Test/Working section information: Test section type (e.g.,
open, closed, adaptive wall) and shape (e.g., circular, square, oval),
length, contraction ratio, maximum air velocity, maximum dynamic
pressure, nozzle width and height, plenum dimensions and net volume,
maximum allowed model scale, maximum model height above road, strut
movement rate (if applicable), model support, primary boundary layer
slot, boundary layer elimination method and photos and diagrams of the
test section;
     Fan section description: Fan type, diameter, power,
maximum rotational speed, maximum tip speed, support type, mechanical
drive, sectional total weight;
     Data acquisition and control (where applicable):
Acquisition type, motor control, tunnel control, model balance, model
pressure measurement, wheel drag balances, wing/body panel balances,
and model exhaust simulation;
     Moving ground plane or Rolling Road (if applicable):
Construction and material, yaw table and range, moving ground length
and width, belt type, maximum belt speed, belt suction mechanism,
platen instrumentation, temperature control, and steering; and
     Facility correction factors and purpose.
(iii) CFD Requirements
    Currently, there is no existing standard, protocol or methodology
governing the use of CFD. Therefore, we are coupling the use of CFD
with empirical measurements from coastdown and wind tunnel procedures.
However, we think it is important to require a minimum set of criteria
that all CFD analysis should follow for the purpose of these rules and
to produce a consistent set of results to maintain compliance. Since
there are primarily two-types of CFD software code, Navier-Stokes based
and Lattice-Boltzman based, we are outlining two sets of criteria to
address both types. Therefore, the agencies propose that manufacturers
use commercially-available CFD software code with a turbulence model
enabled and Navier-Stokes formula solver, where applicable. Further
details and criteria for each type of commercially-available CFD
software code follows immediately and general criteria for all CFD
analysis are subsequently described.
    For Navier-Stokes based CFD code, manufacturers must perform an

unstructured, time-accurate analysis using a mesh grid size with total
surface elements greater than or equal to 5 million cells/nodes, a
near-vehicle cell size of less than or equal to 10 millimeters (mm), a
near-wall cell size of less than or equal to 1mm,\203\ and a volume
element size of less than or equal to 5 mm; using hexagonal or
polyhedral mesh cell shapes. All Navier-Stokes based CFD analysis
should be performed with a k-epsilon (k-[egr]) or a shear stress
transport k-omega (SST k-[omega]) turbulence model and mesh deformation
enabled with boundary layer resolution of +/- 95%. Finally, Navier-
Stokes based CFD analysis for the purposes of determining the Cd should
be performed once result convergence is achieved and manufacturers
should be able to demonstrate convergence by supplying multiple,
successive convergence values.
---------------------------------------------------------------------------

    \203\ See Lecture Notes in Applied and Computational Mechanics,
The Aerodynamics of Heavy Vehicles II: Trucks, Buses, and Trains;
DOI: 10.1007/978-3-540-85070-0--33; ``Applicability of Commercial
CFD tools for assessment of heavy vehicle aerodynamic
characteristics'' as created by the University of Chicago as
Operator of Argonne National Laboratory (``Argonne'') under contract
No. W-31-109-ENG-38 with the U.S. Department of Energy.
---------------------------------------------------------------------------

    For Lattice-Boltzman based CFD code, the agencies propose that
manufacturers perform an unstructured, time-accurate analysis using a
mesh grid size with total surface elements greater than or equal to 5
million cells/nodes, a near-vehicle cell size of less than or equal to
10 millimeters (mm), a near-wall cell size of less than or equal to
1mm, and a volume element size of less than or equal to 5 mm; using
cubic volume elements and triangle and/or quadrilateral surface
elements.
    Finally, in general for CFD, all analysis should be conducted
assuming zero yaw angle for comparison to the coastdown test procedure.
In addition, the ambient conditions assumed for the CFD analysis should
be defined according to the environmental conditions that the
manufacturer is seeking to simulate. For simulating a wind tunnel test,
the CFD analysis should accurately model that wind tunnel and assume a
wind tunnel blockage ratio consistent with SAE J1252 or that matches
the selected wind tunnel, whichever is lower. For simulation of open
road conditions similar to that experienced during coastdown test
procedures, the CFD analysis should assume a blockage ratio of less
than or equal 0.2%.
    The agencies seek comment on the use of CFD commercial or open
source code and the criteria set forth above for conducting the
analysis.
    Finally, in general for each of the allowed aerodynamic assessment
methods, we are requesting comment on the list of information that must
be provided for facilities and test conditions.
Annual Testing and Data Submittal for Aerodynamic Assessment
    Once the manufacturer has performed acceptance demonstration, the
aerodynamic assessment can be used to generate Cd values for all
vehicle models the manufacturer plans to certify and introduce into
commerce. For each model, the manufacturer would supply a predicted Cd
based for each of the other models in the manufacturer's fleet and the
other conditions used to determine the base Cd. This reduces burden on
the manufacturer to perform aerodynamic assessment but provides data
for all the models in a manufacturer's fleet. If a manufacturer has
previously performed aerodynamic assessment on the other models, the
manufacturer may submit an experimental Cd in lieu of a predicted Cd.
    The aerodynamic assessment data would be used by the manufacturer
who would input the Cd value from the look-up table, based on the
results from the aerodynamic assessment, into GEM and determine a GHG
emissions and fuel consumption level.
    Since the agency may input the data into the model, manufacturers
would provide the information described above for acceptance
demonstration for the purposes of annual certification. In addition,
the manufacturer would supply manufacturer fleet information to the
agency for annual certification purposes along with the acceptance
demonstration parameters: manufacturer name, model year, model line (if
different than manufacturer name), model name, engine family, engine
displacement, transmission name and type, number of axles, axle ratio,
vehicle dimensions, including frontal area, predicted or measured
coefficient of drag, assumptions used in developing the predicted or
measured Cd. justification for carry-across of aerodynamic assessment
data, photos of the model line-up, if available, and model applications
and usage options.
    We are requesting comment on the annual testing requirements and
the burden on manufacturers to satisfy the requirements.
(e) Aerodynamic Assessment Validation and Compliance
    Although the procedures above should ensure accuracy in the
aerodynamic assessment, it is always beneficial to perform confirmation
or validation post-certification. The agencies would like to ensure a
level playing field among the manufacturers and the different
aerodynamic assessment methods. The agencies hope to finalize a method
for doing so after working through the comments from all stakeholders
in a collaborative manner.
    The agencies envision that a program for aerodynamic assessment
could consist of two parts: (1) Validation of the manufacturer source
data by performing an audit of the manufacturer's aerodynamic
assessment methods and tools as described in this proposal using a
reference truck and/or (2) vehicle confirmatory evaluation using a
vehicle recruited from the in-use fleet and performing the aerodynamic
assessment discussed in this proposal, either using the manufacturer's
facility and tools or using the agency's facility and tools. We are
seeking comment on the all aspects of an aerodynamic assessment
validation and compliance.

E. Class 2b-8 Vocational Vehicles

(1) Proposed Compliance Approach
    Like Class 7 and 8 combination tractors, heavy-duty vocational
vehicles would be required to have both engine and complete vehicle
certificates of conformity. As discussed in the engine certification
section, engines that will be used in vocational vehicles would need to
be certified using the Heavy-duty FTP cycle for GHG pollutants and show
compliance through the useful life of the engine. This certification is
in addition to the current requirements for obtaining a certificate of
conformity for criteria pollutant emissions.
    For this proposal, the majority of the GHG reduction for vocational
vehicles is expected to come from the use of LRR tires as well as
increased utilization of hybrid powertrain systems. Other technologies
such as aerodynamic improvements and vehicle speed limiting systems are
not as relevant for this class of vehicles, since the typical duty
cycle is much more urban, consisting of lower speeds and frequent
stopping. Idle reduction strategies are expected to be encompassed by
hybrid technology, which we anticipate will ultimately handle PTO
operation. Therefore, for this initial proposal, certification of
heavy-duty vocational vehicles with conventional powertrains will focus
on quantifying GHG benefits due to the use of LRR tires.

(a) Certification Process
    Vehicles would be divided into test groups for purposes of
certification. As with Class 7 and 8 combination tractors, these are
groups of vehicles within a given regulatory category that are expected
to share common emission characteristics. Vocational vehicle regulatory
subcategories share the same structure as those used for heavy-duty
engine criteria pollutant certification and are based on GVWR. This
includes light-heavy (LHD) with a GVWR at or below 19,500 pounds,
medium-heavy (MHD) with a GVWR above 19,500 pounds and at or below
33,000 pounds, and heavy-heavy (HHD) with a GVWR above 33,000 pounds.
Other test group features may include the type of tires used, intended
application, and number of wheels.
    As with Class 7 and 8 combination tractors, we anticipate using the
standardized 12-digit naming convention to identify vocational vehicle
test groups. As with engines and Class 7 and 8 combination tractors,
each certifying vehicle manufacturer would have a unique three digit
code assigned to them. Currently, there is no 5th digit (industry
sector) code for this class of vehicles, for which we propose to use
the next available character, ``3.'' Since we are proposing that the
engine is one of several test-group defining features, we still believe
it is appropriate to include engine displacement in the family name. If
the test-group consists includes multiple engine models with varying
displacements, the largest would be specified in the test-group name,
consistent with current practices. The remaining characters would
remain available for California ARB and/or manufacturer use, such that
the result is a unique test-group name.
    Each test group would need to demonstrate compliance with emission
standards using the GEM approach. Additional provisions are available
for certification of hybrid vehicles or vehicles using unique
technologies, which was detailed in Section IV. If the test group
consists of multiple models, only result from the worst-case model is
necessary for certification. However, manufacturers would need to
submit an engineering evaluation demonstrating that the test group has
been assembled appropriately and that the test model indeed reflects
the worst-case model. Also, manufacturers should plan on submitting
tire rolling resistance properties to EPA at the time of certification.
Finally the data from each of the certification cycles described below
will need to be submitted at the time of certification.
(b) Demonstrating Compliance With the Proposed Standards
(i) CO2 and Fuel Consumption Standards
Model
    For this proposal, the agencies are proposing that demonstrating
compliance with GHG and fuel consumption standards would primarily
involve demonstrating the use of LRR tires and quantifying the
associated CO2 and fuel consumption benefit. Similar to
Class 7 and 8 combination tractors, this will be done using GEM.
However, the input parameters entered by the vehicle manufacturer would
be limited to the properties of the tires. GEM will use the tire data,
along with inputs reflecting a baseline truck and engine, to generate a
complete vehicle model. The test weight used in the model will be based
on the vehicle class, as identified above. Light-heavy-duty vehicles
will have a test weight of 16,000 pounds; 25,150 pounds for medium
heavy-duty vehicles; and heavy heavy-duty vocational vehicles will use
a test weight of 67,000 pounds. The model would then be exercised over
the HHDDT transient cycle as well as 55 and 65 mph steady-state cruise
conditions. The results of each of the three tests would be weighted at
37%, 21%, and 42% for 65 mph, 55 mph, and transient tests,
respectively.
    It may seem more expedient and just as accurate to require
manufacturers use tires meeting certain industry standards for
qualifying tires as having LRR. In addition, CO2 and fuel
consumption benefits could be quantified for different ranges of
coefficients of rolling resistance to provide a means for comparison to
the standard. However, we believe that as technology advances, other
aspects of vocational vehicles may warrant inclusion in future
rulemakings. For this reason, we believe it is important to have the
certification framework in place to accommodate such additions. While
the modeling approach may seem to be overly complicated for this phase
of the rules, it also serves to create a certification pathway for
future rulemakings and therefore we believe this is the best approach.
Should innovative technologies be considered that are currently beyond
the scope of the model, it would be necessary for the manufacturer to
conduct A to B testing which reflects the improvement associated with
the new technology. The test protocol to be used and the basis of this
assessment will require a public vetting process which would likely
include notice and comment.
In-use Standards
    The category of wear items primarily relates to tires. It is
expected that vehicle manufacturers will equip their trucks with LRR
(LRR) tires, since the proposed vehicle standard is predicated on LRR
tires' performance. The tire replacement intervals for this class of
vehicle is normally in the range of 50,000 to 100,000 miles, which
means the owner/operator will be replacing the tires at several points
within the useful life of the vehicle. We believe that as LRR tires
become more common on new equipment, the aftermarket prices of these
tires will also decrease. Along with decreasing tire prices, the fuel
savings realized through use of LRR tires will ideally provide enough
incentive for owner/operators to continue purchasing these tires. The
inventory modeling in this proposal reflects the continued use of LRR
tires through the life of the vehicle. We seek comment on this and all
aspects of our inventory modeling.
(ii) Evaporative Emission Standards
    Evaporative and refueling emissions from heavy-duty highway engines
and vehicles are currently regulated under 40 CFR part 86. Even though
these emission standards apply to the same engines and vehicles that
must meet exhaust emission standards, we require a separate certificate
for complying with evaporative and refueling emission standards. An
important related point to note is that the evaporative and refueling
emission standards always apply to the vehicle, while the exhaust
emission standards may apply to either the engine or the vehicle. For
vehicles other than pickups and vans, the standards proposed in this
notice to address greenhouse gas emissions apply separately to engines
and to vehicles. Since we plan to apply both greenhouse gas standards
and evaporative/refueling emission standards to vehicle manufacturers,
we believe it would be advantageous to have the regulations related to
their certification requirements written together as much as possible.
EPA regards these proposed changes as discrete, minimal, and for the
most part clarifications to the existing standards. Except as
specifically proposed here, EPA is not soliciting comment on, or
otherwise considering whether to make changes to those standards.
Accordingly, EPA will not consider any comments directed to any aspect
of these standards other than those specifically proposed here.
    We are generally not proposing to change the evaporative or
refueling emission standards, but we have come

across several provisions that warrant clarification or correction:
     When adopting the most recent evaporative emission change
we did not carry through the changes to the regulatory text applying
evaporative emission standards for methanol-fueled compression-ignition
engine. The proposed regulations correct this by applying the new
standards to all fuels that are subject to standards.
     We are proposing provisions to address which standards
apply when an auxiliary (nonroad) engine is installed in a motor
vehicle, which is currently not directly addressed in the highway
regulation. The proposed approach would require testing complete
vehicles with any auxiliary engines (and the corresponding fuel-system
components). Incomplete vehicles would be tested without the auxiliary
engines, but any such engines and the corresponding fuel-system
components would need to meet the standards that apply under our
nonroad program as specified in 40 CFR part 1060.
     We are proposing to remove the option for secondary
vehicle manufacturers to use a larger fuel tank capacity than is
specified by the certifying manufacturer without re-certifying the
vehicle. Secondary vehicle manufacturers needing a greater fuel tank
capacity would need to either work with the certifying manufacturer to
include the larger tank, or go through the effort to re-certify the
vehicle itself. Our understanding is that this provision has not been
used and would be better handled as part of certification rather than
managing a separate process. We are proposing corresponding changes to
the emission control information label.
     Rewriting the regulations in a new part in conjunction
with the greenhouse gas standards allows for some occasions of improved
organization and clarity, as well as updating various provisions. For
example, we are proposing a leaner description of evaporative emission
families that does not reference sealing methods for carburetors or air
cleaners. We are also clarifying how evaporative emission standards
affect engine manufacturers and proposing more descriptive provisions
related to certifying vehicles above 26,000 pounds GVWR using
engineering analysis.
     Since we adopted evaporative emission standards for
gaseous-fuel vehicles, we have developed new approaches for design-
based certification (see, for example, 40 CFR 1060.240). We request
comment on changing the requirements related to certifying gaseous-fuel
vehicles to design-based certification. This would allow for a simpler
assessment for certifying these vehicles without changing the standards
that apply.
(2) Proposed Labeling Provisions
    It is crucial that a means exist for allowing field inspectors to
identify whether a vehicle is certified, and if so, whether it is in
the certified configuration. As with engines and tractors, we believe
an emission control information label is a logical first step in
facilitating this identification. For vocational vehicles, the engine
will have a label that is permanently affixed to the engine and
identify the engine as certified for use in a certain regulatory
subcategory of vehicle (i.e., MHD, etc.).
    The vehicle will also have a label listing the test group, engine
family, and range of tire rolling resistances that the vehicle is
certified to use. In addition, if any other emission related components
are present, such as hybrid powertrains, key components will also need
to be specified on the label. Like the engine label, this will need to
be permanently affixed to the vehicle in an area that is clearly
accessible to the owner/operator.
    At the time of certification, manufacturers will be required to
submit an example of their vehicle emission control label such that EPA
can verify that all critical elements are present. Such elements
include the vehicle family/test group name, emission control system
identifiers described above, regulatory sub-category of the vehicle,
and Family Emission Limits to which the vehicle is certified to. In
addition to the label, manufacturers will also need to describe where
the unique vehicle identification number and date of production can be
found on the vehicle.
(3) Other Certification Issues
Warranty
    As with other heavy-duty engine and vehicle regulatory categories,
vocational vehicle chassis manufacturers would be required to warrant
their product to be free from defects that would adversely affect
emissions. This warranty also covers the failure of emission related
components for the useful life of the vehicle. For vocational chassis,
the key emission related component addressed in this proposal is the
tires.
    Manufacturers of chassis for vocational vehicles would be required
to warrant tires to be free from defects at the time of initial sale.
As with Class 7 and 8 combination tractors, we expect the chassis
manufacturer to only warrant tires the original tires against
manufacturing or design-related defects. This tire warranty would not
cover replacement tires or damage from road hazards or improper
inflation.
    As with Class 7 and 8 combination tractors, all warranty
documentation would be submitted to EPA at the time of certification.
This should include the warranty statement provided to the owner/
operator, description of the service repair network, list of covered
components (both conventional and high-cost), and length of coverage.
EPA Certification Fees
    Similar to engine and tractor-trailer vehicle certification, the
agency will assess certification fees for vocational vehicles. The
proceeds from these fees are used to fund the compliance and
certification activities related to GHG regulation for this industry
segment. In addition to the certification process, other activities
funded by certification fees include EPA-administered in-use testing,
selective enforcement audits, and confirmatory testing. At this point,
the exact costs associated with the heavy-duty vehicle GHG compliance
are not well known. EPA will assess its compliance program associated
with this proposal and assess the appropriate level of fees. We
anticipate that fees will be applied based on test groups, following
the light-duty vehicle approach.
Maintenance
    Vehicle manufacturers are required to outline maintenance schedules
that ensure their product will remain in compliance with emission
standards throughout the useful life of the vehicle. For heavy-duty
vehicles, such maintenance may include fluid/lubricant service, fairing
adjustments, or service to the GHG emission control system. This
schedule is required to be submitted as part of the application for
certification. Maintenance that is deemed to be critical to ensuring
compliance with emission standards is classified as ``critical
emission-related maintenance.'' Generally, manufacturers are
discouraged from specifying that critical emission-related maintenance
is needed within the regulatory useful life of the engine. However, if
such maintenance is unavoidable, manufacturers must have a reasonable
basis for ensuring it is performed at the correct time. This may be
demonstrated through several methods including survey data indicating
that at least 80% of engines receive the required maintenance in-use or
manufacturers may provide the maintenance at no charge to the user.

F. General Regulatory Provisions

(1) Statutory Prohibited Acts
    Section 203 of the CAA describes acts that are prohibited by law.
This section and associated regulations apply equally to the greenhouse
gas standards as to any other regulated emission. Acts that are
prohibited by section 203 of the CAA include the introduction into
commerce or the sale of an engine or vehicle without a certificate of
conformity, removing or otherwise defeating emission control equipment,
the sale or installation of devices designed to defeat emission
controls, and other actions. In addition, vehicle manufacturers, or any
other party, may not make changes to the certified engine that would
result in it not being in the certified configuration.
    EPA proposes to apply Sec.  86.1854-12 to heavy-duty vehicles and
engines; this codifies the prohibited acts spelled out in the statute.
Although it is not legally necessary to repeat what is in the CAA, EPA
believes that including this language in the regulations provides
clarity and improves the ease of use and completeness of the
regulations. Since this change merely codifies provisions that already
apply, there is no burden associated with the change.
(2) Regulatory Amendments Related to Heavy-Duty Engine Certification
    We are proposing to adopt the new engine-based greenhouse gas
standards in 40 CFR part 1036 and the new vehicle-based standards in 40
CFR part 1037. We are proposing to continue to rely on 40 CFR parts 85
and 86 for conventional certification and compliance provisions related
to criteria pollutants, but the proposed regulations include a variety
of amendments that would affect the provisions that apply with respect
to criteria pollutants. We are not intending to change the stringency
of, or otherwise substantively change any existing standards.
    The introduction of new parts in the CFR is part of a long-term
plan to migrate all the regulatory provisions related to highway and
nonroad engine and vehicle emissions to a portion of the CFR called
Subchapter U, which consists of 40 CFR parts 1,000 through 1299. We
have already adopted emission standards, test procedures, and
compliance provisions for several types of engines in 40 CFR parts 1033
through 1074. We intend eventually to capture all the regulatory
requirements related to heavy-duty highway engines and vehicles in
these new parts. Moving regulatory provisions to the new parts allows
us to publish the regulations in a way that is better organized,
reflects updates to various certification and compliance procedures,
provides consistency with other engine programs, and is written in
plain language. We have already taken steps in this direction for
heavy-duty highway engines by adopting the engine-testing procedures in
40 CFR part 1065 and the provisions for selective enforcement audits in
40 CFR part 1068.
    EPA solicits comment on these proposed drafting changes and
additions. This solicitation relates solely to the appropriate
migration, translation, and enhancement of existing provisions. EPA is
not soliciting comment on the substance of these existing rules, and is
not proposing to amend, reconsider, or otherwise re-examine these
provisions' substantive effect.
    The rest of this section describes the most significant of these
proposed redrafting changes. The proposal includes several changes to
the certification and compliance procedures, including the following:
     We propose to require that engine manufacturers provide
installation instructions to vehicle manufacturers (see Sec.
1036.130). We expect this is already commonly done; however, the
regulatory language spells out a complete list of information we
believe is necessary to properly ensure that vehicle manufacturers
install engines in a way that is consistent with the engine's
certificate of conformity.
     Sec.  1036.30, Sec.  1036.250, and Sec.  1036.825 spell
out several detailed provisions related to keeping records and
submitting information to us.
     We wrote the greenhouse gas regulations to divide heavy-
duty engines into ``spark-ignition'' and ``compression-ignition''
engines, rather than ``Otto-cycle'' and ``diesel'' engines, to align
with our terminology in all our nonroad programs. This will likely
involve no effective change in categorizing engines except for natural
gas engines. To address this concern, we would include a provision in
Sec.  1036.150 to allow manufacturers to meet standards for spark-
ignition engines if they were regulated as Otto-cycle engines in 40 CFR
part 86, and vice versa.
     Sec.  1036.205 describes a new requirement for imported
engines to describe the general approach to importation (such as
identifying authorized agents and ports of entry), and identifying a
test lab in the United States where EPA can perform testing on
certified engines. These steps are part of our ongoing effort to ensure
that we have a compliance and enforcement program that is as effective
for imported engines as for domestically produced engines. We have
already adopted these same provisions for several types of nonroad
engines.
     Sec.  1036.210 specifies a process by which manufacturers
are able to get preliminary approval for EPA decisions for questions
that require lead time for preparing an application for certification.
This might involve, for example, preparing a plan for durability
testing, establishing engine families, identifying adjustable
parameters, and creating a list of scheduled maintenance items.
     Sec.  1036.225 describes how to amend an application for
certification.
     We are proposing to apply the exemption and recall
provisions as written in 40 CFR part 1068 instead of the comparable
provisions in 40 CFR part 85. This involves only minor changes relative
to current practice.
    We are aware that it may be appropriate to move several additional
provisions in 40 CFR parts 85 and 86 to subchapter U. For example,
highway engine manufacturers may find it preferable to use the same
parameters specified for defining nonroad engine families for
certifying highway engines. To the extent that the nonroad provisions
would apply appropriately for highway engines, we and the manufacturers
would benefit from a consistent approach to certifying both types of
engines in a way that does not compromise the degree of emission
control achieved under the existing standards.
    Another area of particular interest is defect reporting. Existing
regulations require manufacturers to report defects to EPA whenever the
same defect occurs at least 25 times. This approach can be somewhat
onerous for manufacturers making high-volume products. For example, for
an engine model with annual sales above 25,000, this represents a
defect rate of less than 0.1 percent. In contrast, the approach to
defect reporting in Sec.  1068.501 accommodates the high sales volumes
associated with highway engines, basing requirements on a percentage of
defective products, rather than setting a fixed number for all engine
families. This flexibility is paired with the explicit direction for
the manufacturer to actively monitor warranty claims, customer
complaints, and other sources of information to evaluate and track
potential defects. We believe this aligns both with the manufacturers'
interest in producing quality products and EPA's interest in addressing
any quality concerns that arise from the need to repair in-use engines
and vehicles.

(3) Test Procedures For Measuring Emissions From Heavy-Duty Vehicles
    We are proposing a new part 1066 that would contain a general
chassis-based test procedures in for measuring emissions from a variety
of vehicles, including vehicles over 14,000 pounds GVWR. However, we
are not proposing to apply these procedures broadly at this time. The
test procedures in 40 CFR part 86 would continue to apply for vehicles
under 14,000 pounds GVWR. Rather, the proposed part 1066 procedures
would apply only for any testing that would be required for larger
vehicles. This could include ``A to B'' hybrid vehicle testing and
coastdown testing. Nevertheless, we will likely consider in the future
applying these procedures also for other heavy-duty vehicle testing and
for light-duty vehicles, highway motorcycles, and/or nonroad
recreational vehicles that rely on chassis-based testing.
    As noted above, engine manufacturers are already using the test
procedures in 40 CFR part 1065 instead of those originally adopted in
40 CFR part 86. The new procedures are written to apply generically for
any type of engine and include the current state of technology for
measurement instruments, calibration procedures, and other practices.
We are proposing the chassis-based test procedures in part 1066 to have
a similar structure.
    The proposed procedures in part 1066 reference large portions of
part 1065 to align test specifications that apply equally to engine-
based and vehicle-based testing, such as CVS and analyzer
specifications and calibrations, test fuels, calculations, and
definitions of many terms. Since several highway engine manufacturers
were involved in developing the full range of specified procedures in
part 1065, we are confident that many of these provisions are
appropriate without modification for vehicle testing.
    The remaining test specifications needed in part 1066 are mostly
related to setting up, calibrating, and operating a chassis
dynamometer. This also includes the coastdown procedures that are
required for establishing the dynamometer load settings to ensure that
the dynamometer accurately simulates in-use driving.
    Current testing requirements related to dynamometer specifications
rely on a combination of regulatory provisions, EPA guidance documents,
and extensive know-how from industry experience that has led to a good
understanding of best practices for operating a vehicle in the
laboratory to measure emissions. We attempted in this proposal to
capture this range of material, organizing these specifications and
verification and calibration procedures to include a complete set of
provisions to ensure that a dynamometer meeting these specifications
would allow for carefully controlled vehicle operation such that
emission measurements are accurate and repeatable. We request comment
on the range of proposed requirements related to designing, building,
and operating chassis dynamometers. For example, we believe that the
proposed verification and calibration procedures in part 1066, subpart
B, for diameter, speed, torque, acceleration, base inertia, friction
loss, and other parameters are all necessary to ensure proper
dynamometer operation. It may be that some of these checks are
redundant, or could be achieved with different procedures. There may
also be additional checks needed to remove possibilities for inadequate
accuracy or precision.
    The procedures are written with the understanding that heavy-duty
highway manufacturers have, and need to have, single-roll electric
dynamometers for testing. We are aware that this is not the case for
other applications, such as all-terrain vehicles. We are not adopting
specific provisions for testing with hydrokinetic dynamometers, we are
already including a provision acknowledging that we may approve the use
of dynamometers meeting alternative specifications if that is
appropriate for the type of vehicle being tested and for the level of
stringency represented by the corresponding emission standards.
    Drafting a full set of test specifications highlights the mixed use
of units for testing. Some chassis-based standards and procedures are
written based largely on the International System of Units (SI), such
as gram per kilometer (g/km) standards and kilometers per hour (kph)
driving, while others are written based largely on English units (g/
mile standards and miles per hour driving). The proposal includes a mix
of SI and English units with instructions about converting units
appropriately. However, most of the specifications and examples are
written in English units. While this seems to be the prevailing
practice for testing in the United States, we understand that vehicle
testing outside the United States is almost universally done in SI
units. In any case, dynamometers are produced with the capability of
operating in either English or SI units. We believe there would be a
substantial advantage toward the goal of achieving globally harmonized
test procedures if we would write the test procedures based on SI
units. This would also in several cases allow for more straightforward
calculations, and reduced risk of rounding errors. For comparison, part
1065 is written almost exclusively in SI units. We request comment on
the use of units throughout part 1066.
    A fundamental obstacle toward using SI units is the fact that some
duty cycles are specified based on speeds in miles per hour. To address
this, it would be appropriate to convert the applicable driving
schedules to meter-per-second (m/s) values. Converting speeds to the
nearest 0.01 m/s would ensure that the prescribed driving cycle does
not change with respect to driving schedules that are specified to the
nearest 0.1 mph. The regulations would include the appropriate mph (or
kph) speeds to allow for a ready understanding of speed values (see 40
CFR part 1037, Appendix I). This would, for example, allow for drivers
to continue to follow a mph-based speed trace. The  2 mph
tolerance on driving speeds could be converted to  1.0 m/s,
which corresponds to an effective speed tolerance of  2.2
mph. This may involve a tightening or loosening of the existing speed
tolerance, depending on whether manufacturers used the full degree of
flexibility allowed for a mph tolerance value that is specified without
a decimal place. Similarly, the Cruise cycles for heavy-duty vehicles
could be specified as 24.5  0.5 m/s (54.8  1.1
mph) and 29.0  0.5 m/s (64.9  1.1 mph).

G. Penalties

    As part of the fuel efficiency improvement program to be created
through this rulemaking, NHTSA is proposing civil penalties for non-
compliance with fuel consumption standards. NHTSA's authority under
EISA, as codified at 49 U.S.C. 32902(k), requires the agency to
determine appropriate measurement metrics, test procedures, standards,
and compliance and enforcement protocols for HD vehicles. NHTSA
interprets its authority to develop an enforcement program to include
the authority to determine and assess civil penalties for non-
compliance, that would impose penalties determined based on the
discussion that follows.
    NHTSA proposes that in cases of non-compliance, the agency would
establish civil penalties based on consideration of the following
factors:
     Actual fuel consumption performance related to the
applicable standard.
     Estimated cost to comply with the regulation and
applicable standard.

     Quantity of vehicles or engines not complying.
     Manufacturer's history of non-compliance.
     The civil penalty should act as a deterrent.
     The financial condition of the manufacturer.
     Civil penalties paid for non-compliance of the same
vehicles under the EPA GHG program.
    NHTSA recognizes that EPA also has authority to impose civil
penalties for non-compliance with GHG regulations. It is not the intent
of either agency to impose duplicative civil penalties, and in the case
of non-compliance with fuel consumption regulations, NHTSA intends to
give consideration to civil penalties imposed by EPA for GHG non-
compliance, as EPA would give consideration to civil penalties imposed
by NHTSA in the case of non-compliance with GHG regulations.\204\
---------------------------------------------------------------------------

    \204\ EPA discussed a similar situation concerning consideration
of civil penalties imposed by NHTSA for CAFE violations for light-
duty vehicles, in the final rule establishing the 2012-2016 MY
standards. See 75 FR 25324 and 25482, May 7, 2010.
---------------------------------------------------------------------------

    The proposed civil penalty amount NHTSA could impose would not
exceed the limit that EPA is authorized to impose under the CAA. The
potential maximum civil penalty for a manufacturer would be calculated
as follows in Equation V-1:

Equation V-1: Aggregate Maximum Civil Penalty

Aggregate Maximum Civil Penalty for a Non-Compliant Regulatory Category
= (CAA Limit) x (production volume within the regulatory category)

    NHTSA seeks comments related to this proposal for a civil penalty
program under EISA.
    EPA has occasionally in the past conducted rulemakings to provide
for nonconformance penalties--monetary penalties that allow a
manufacturer to sell engines or vehicles that do not meet an emissions
standard. Nonconformance penalties are authorized for heavy-duty
engines and vehicles under section 206(g) of the CAA. Three basic
criteria have been established by rulemaking for determining the
eligibility of emissions standards for nonconformance penalties in any
given model year: (1) The emissions standard in question must become
more difficult to meet, (2) substantial work must be required in order
to meet the standard, and (3) a technological laggard must be likely to
develop (40 CFR 86.1103-87). A technological laggard is a manufacturer
who cannot meet a particular emissions standard due to technological
(not economic) difficulties and who, in the absence of nonconformance
penalties, might be forced from the marketplace. The process to
determine if these criteria are met and to establish penalty amounts
and conditions is carried out via rulemaking, as required by the CAA.
The CAA (in section 205) also lays out requirements for the assessment
of civil penalties for noncompliance with emissions standards.
    As discussed in detail in Section III, the agencies have determined
that the proposed GHG and fuel consumption standards are readily
feasible, and we do not believe a technological laggard will emerge in
any sector covered by these proposed standards. In addition to the
standards being premised on use of already-existing, cost-effective
technologies, there are a number of flexibilities and alternative
standards built into the proposal. However, we do request comment
regarding this assessment and on whether or not it would be appropriate
for EPA and NHTSA to initiate rulemaking activity to set nonconformance
penalties for the proposed standards, subject to their respective
statutory authorities. Should nonconformance penalties be warranted,
the benefits of establishing them would be threefold: (1) The EPA and
NHTSA programs would continue to be equivalent, allowing manufacturers
to sell the same vehicles and engines to satisfy both programs, (2)
competitiveness in the affected HD sector would be maintained,
preserving jobs and consumer choices, and (3) nonconformance penalties
would be set through a transparent public process, involving notice and
public hearing.

VI. How would this proposed program impact fuel consumption, GHG
emissions, and climate change?

A. What methodologies did the agencies use to project GHG emissions and
fuel consumption impacts?

    EPA and NHTSA used EPA's official mobile source emissions inventory
model named Motor Vehicle Emissions Simulator (MOVES2010),\205\, to
estimate emission and fuel consumption impacts of these proposed rules.
MOVES has capability to take in user inputs to modify default data to
better estimate emissions for different scenarios, such as different
regulatory alternatives, state implementation plans (SIPs), geographic
locations, vehicle activity, and microscale projects.
---------------------------------------------------------------------------

    \205\ MOVES homepage: http://www.epa.gov/otaq/models/moves/
index.htm. Version MOVES2010 was used for emissions impacts analysis
for this proposal. Current version as of September 14, 2010 is an
updated version named MOVES2010a, available directly from the MOVES
homepage. To replicate results from this proposal, MOVES2010 must be
used.
---------------------------------------------------------------------------

    The agencies performed multiple MOVES runs to establish reference
case and control case emission inventories and fuel consumption values.
The agencies ran MOVES with user input databases that reflected
characteristics of the proposed rules, such as emissions improvements
and recent sales projections. Some post-processing of the model output
was required to ensure proper results. The agencies ran MOVES for non-
GHGs, CO2, CH4, and N2O for calendar
years 2005, 2018, 2030, and 2050. Additional runs were performed for
just the three greenhouse gases and for fuel consumption for every
calendar year from 2014 to 2050, inclusive, which fed the economy-wide
modeling, monetized benefits estimation, and climate impacts analysis.
    The agencies also used MOVES to estimate emissions and fuel
consumption impacts for the other alternatives considered and described
in Section IX.

B. MOVES Analysis

(1) Inputs and Assumptions
(a) Reference Run Updates
    Since MOVES2010 vehicle sales and activity data were developed from
AEO2006, EPA first updated these data using sales and activity
estimates from AEO2010. EPA also updated the fuel supply information in
MOVES to reflect a 100% E10 ``gasoline'' fuel supply to reflect the
Renewable Fuels Standard.\206\ MOVES2010 defaults were used for all
other parameters to estimate the reference case emissions inventories.
---------------------------------------------------------------------------

    \206\ Renewable Fuels Standard available at http://www.epa.gov/
otaq/fuels/renewablefuels/index.htm.
---------------------------------------------------------------------------

(b) Control Run Updates
    EPA developed additional user input data for MOVES runs to estimate
control case inventories. To account for improvements of engine and
vehicle efficiency, EPA developed several user inputs to run the
control case in MOVES. Since MOVES does not operate based on Heavy-duty
FTP cycle results, EPA used the percent reduction in engine
CO2 emissions expected due to the proposed rules to develop
energy inputs for the control case runs. Also, EPA used the percent
reduction in aerodynamic drag coefficient and tire rolling resistance
coefficient expected from the proposed rules to develop road load input
for the control case. The fuel supply update used in the reference case
was used in the control case. Details of all the MOVES runs, input

data tables, and post-processing are available in the docket (EPA-HQ-
OAR-2010-0162).
    Table VI-1 and Table VI-2 describe the estimated expected
reductions from these proposed rules, which were input into MOVES for
estimating control case emissions inventories.
[GRAPHIC] [TIFF OMITTED] TP30NO10.049

    Since nearly all HD pickup trucks and vans will be certified on a
chassis dynamometer, the CO2 reductions for these vehicles
will not be represented as engine and road load reduction components,
but total vehicle CO2 reductions. These estimated reductions
are described in Table VI-3.
---------------------------------------------------------------------------

    \207\ Section II discusses an alternative engine standard
proposed for the HD diesel engines in the 2014, 2015, and 2016 model
years. To the extent that engines using this alternative would be
expected to have baseline emissions greater than the industry
average, the reduction from the industry average projected in this
proposal could be reduced.
[GRAPHIC] [TIFF OMITTED] TP30NO10.050

(C) What are the projected reductions in fuel consumption and GHG
emissions?

    EPA and NHTSA expect significant reductions in GHG emissions and
fuel consumption from these proposed rules--emission reductions from
both downstream (tailpipe) and upstream (fuel production and
distribution) sources, and fuel consumption reductions from more
efficient vehicles. Increased vehicle efficiency and reduced vehicle
fuel consumption would also reduce GHG emissions from upstream sources.
The following subsections summarize the GHG emissions and fuel
consumption reductions expected from these proposed rules.
(1) Downstream (Tailpipe)
    EPA used MOVES to estimate downstream GHG inventories from these
proposed rules. We expect reductions in CO2 from all heavy-
duty vehicle categories. The reductions come from engine and vehicle
improvements. EPA expects CH4 and N2O emissions
to increase very slightly because of a rebound in vehicle miles
traveled (VMT) and because significant vehicle reductions of these two
GHGs are not expected from these proposed rules. Overall, downstream
GHG emissions will be reduced significantly, and is described in the
following subsections.
    For CO2 and fuel consumption, the total energy
consumption ``pollutant'' was run in MOVES rather than CO2
itself. The energy was converted to fuel consumption based on fuel
heating values assumed in the Renewable Fuels Standard and used in the
development of MOVES emission and energy rates. These values are
117,250 kJ/gallon for E10 \208\ and 138,451 kJ/gallon for diesel.\209\
To calculate CO2, the agencies assumed a CO2
content of 8,576 g/gallon for E10 and 10,180 g/gallon for diesel. Table
VI-4 shows the fleet-wide GHG reductions and fuel savings from
reference case to control case through the lifetime of model year 2014
through 2018 heavy-duty vehicles. Table VI-5 shows the downstream GHG
emissions reductions and fuel savings in 2018, 2030, and 2050.
---------------------------------------------------------------------------

    \208\ Renewable Fuels Standards assumptions of 115,000 BTU/
gallon gasoline (E0) and 76,330 BTU/gallon ethanol (E100) weighted
90% and 10%, respectively, and converted to kJ at 1.055 kJ/BTU.
    \209\ MOVES2004 Energy and Emission Inputs. EPA420-P-05-003,
March 2005. http://www.epa.gov/otaq/models/ngm/420p05003.pdf.
[GRAPHIC] [TIFF OMITTED] TP30NO10.051

(2) Upstream (Fuel Production and Distribution)
    Upstream GHG emission reductions associated with the production and
distribution of fuel were projected using emission factors from DOE's
``Greenhouse Gases, Regulated Emissions, and Energy Use in
Transportation'' (GREET1.8) model, with some modifications consistent
with the Light-Duty Greenhouse Gas rulemaking. More information
regarding these modifications can be found in the draft RIA Chapter 5.
These estimates include both international and domestic emission
reductions, since reductions in foreign exports of finished gasoline
and/or crude would make up a significant share of the fuel savings
resulting from the GHG standards. Thus, significant portions of the
upstream GHG emission reductions will occur outside of the United
States; a breakdown and discussion of projected international versus
domestic reductions is included in the draft RIA Chapter 5. GHG
emission reductions from upstream sources can be found in Table VI-6.

[GRAPHIC] [TIFF OMITTED] TP30NO10.052

(3) HFC Emissions
    Based on projected HFC emission reductions due to the proposed AC
leakage standards, EPA estimates the HFC reductions to be 118,885
metric tons of CO2eq in 2018, 355,576 metric tons of
CO2eq emissions in 2030 and 417,584 metric tons
CO2eq in 2050, as detailed in draft RIA Chapter 5.3.4.
(4) Total (Upstream + Downstream + HFC)
    Table VI-7 combines downstream results from Table VI-5, upstream
results Table VI-6, and HFC results to show total GHG reductions for
calendar years 2018, 2030, and 2050.
[GRAPHIC] [TIFF OMITTED] TP30NO10.053

D. Overview of Climate Change Impacts From GHG Emissions

    Once emitted, GHGs that are the subject of this regulation can
remain in the atmosphere for decades to centuries, meaning that (1)
their concentrations become well-mixed throughout the global atmosphere
regardless of emission origin, and (2) their effects on climate are
long lasting. GHG emissions come mainly from the combustion of fossil
fuels (coal, oil, and gas), with additional contributions from the
clearing of forests and agricultural activities. Transportation
activities, in aggregate, are the second largest contributor to total
U.S. GHG emissions (27 percent) despite a decline in emissions from
this sector during 2008.\210\
---------------------------------------------------------------------------

    \210\ U.S. EPA (2010) Inventory of U.S. Greenhouse Gas Emissions
and Sinks: 1990-2007. EPA-430-R-10-006, Washington, DC.
---------------------------------------------------------------------------

    This section provides a summary of observed and projected changes
in GHG emissions and associated climate change impacts. The source
document for the section below is the Technical Support Document (TSD)
\211\ for EPA's Endangerment and Cause or Contribute Findings Under the
Clean Air Act (74 FR 66496, December 15, 2009). Below is the Executive
Summary of the TSD which provides technical support for the
endangerment and cause or contribute analyses concerning GHG emissions
under section 202(a) of the CAA. The TSD reviews observed and projected
changes in climate based on current and projected atmospheric GHG
concentrations and emissions, as well as the related impacts and risks
from climate change that are projected in the absence of GHG mitigation
actions, including this proposal and other U.S. and global actions. The
TSD was updated and revised based on expert technical review and public
comment as part of EPA's rulemaking process for the final Endangerment
Findings. The key findings synthesized here and the information
throughout the TSD are primarily drawn from the assessment reports of
the Intergovernmental Panel on Climate Change (IPCC), the U.S. Climate
Change Science Program (CCSP), the U.S. Global Change Research Program
(USGCRP), and NRC.\212\
---------------------------------------------------------------------------

    \211\ See Endangerment TSD, Note 9 above.
    \212\ For a complete list of core references from IPCC, USGCRP/
CCSP, NRC and others relied upon for development of the TSD for
EPA's Endangerment and Cause or Contribute Findings see section
1(b), specifically, Table 1.1 of the TSD Docket: EPA-HQ-OAR-2009-
0171-11645.
---------------------------------------------------------------------------

    In May 2010, the NRC published its comprehensive assessment,
``Advancing the Science of Climate Change.'' \213\ It concluded that
``climate change is occurring, is caused largely by human activities,
and poses significant risks for--and in many cases is already
affecting--a broad range of human and natural systems.'' Furthermore,
the NRC stated that this conclusion is based on findings that are
``consistent with the conclusions of recent assessments by the U.S.
Global Change Research Program, the Intergovernmental Panel on Climate
Change's Fourth Assessment Report, and other assessments of the state
of scientific knowledge on climate change.'' These are the same
assessments that served as the primary scientific references underlying
the Administrator's Endangerment Finding. Importantly, this recent NRC
assessment represents another independent and critical inquiry of the
state of climate change science, separate and apart from the previous
IPCC and USGCRP assessments. The NRC assessment is a clear affirmation
that the scientific underpinnings of the Administrator's Endangerment
Finding are robust, credible, and appropriately characterized by EPA.
---------------------------------------------------------------------------

    \213\ National Research Council (NRC) (2010). Advancing the
Science of Climate Change. National Academy Press. Washington, DC.
---------------------------------------------------------------------------

(1) Observed Trends in Greenhouse Gas Emissions and Concentrations
    The primary long-lived GHGs directly emitted by human activities
include CO2, CH4, N2O, HFCs, PFCs, and
SF6. Greenhouse gases have a warming effect by trapping heat
in the atmosphere that would otherwise escape to space. In 2007, U.S.
GHG emissions were 7,150

teragrams \214\ of CO2 equivalent \215\
(TgCO2eq). The dominant gas emitted is CO2,
mostly from fossil fuel combustion. Methane is the second largest
component of U.S. emissions, followed by N2O and the fluorinated gases
(HFCs, PFCs, and SF6). Electricity generation is the largest emitting
sector (34% of total U.S. GHG emissions), followed by transportation
(27%) and industry (19%).
---------------------------------------------------------------------------

    \214\ One teragram (Tg) = 1 million metric tons. 1 metric ton =
1,000 kilograms = 1.102 short tons = 2,205 pounds.
    \215\ Long-lived GHGs are compared and summed together on a
CO2-equivalent basis by multiplying each gas by its
global warming potential (GWP), as estimated by IPCC. In accordance
with United Nations Framework Convention on Climate Change (UNFCCC)
reporting procedures, the U.S. quantifies GHG emissions using the
100-year timeframe values for GWPs established in the IPCC Second
Assessment Report.
---------------------------------------------------------------------------

    Transportation sources under section 202(a) \216\ of the CAA
(passenger cars, light-duty trucks, other trucks and buses,
motorcycles, and passenger cooling) emitted 1,649 TgCO2eq in
2007, representing 23% of total U.S. GHG emissions. U.S. transportation
sources under section 202(a) made up 4.3% of total global GHG emissions
in 2005,\217\ which, in addition to the United States as a whole,
ranked only behind total GHG emissions from China, Russia, and India
but ahead of Japan, Brazil, Germany, and the rest of the world's
countries. In 2005, total U.S. GHG emissions were responsible for 18%
of global emissions, ranking only behind China, which was responsible
for 19% of global GHG emissions. The scope of this proposal focuses on
GHG emissions under section 202(a) from heavy-duty source categories
(see Section V).
---------------------------------------------------------------------------

    \216\ Source categories under Section 202(a) of the CAA are a
subset of source categories considered in the transportation sector
and do not include emissions from non-highway sources such as boats,
rail, aircraft, agricultural equipment, construction/mining
equipment, and other off-road equipment.
    \217\ More recent emission data are available for the United
States and other individual countries, but 2005 is the most recent
year for which data for all countries and all gases are available.
---------------------------------------------------------------------------

    The global atmospheric CO2 concentration has increased
about 38% from pre-industrial levels to 2009, and almost all of the
increase is due to anthropogenic emissions. The global atmospheric
concentration of CH4 has increased by 149% since pre-
industrial levels (through 2007); and the N2O concentration
has increased by 23% (through 2007). The observed concentration
increase in these gases can also be attributed primarily to
anthropogenic emissions. The industrial fluorinated gases, HFCs, PFCs,
and SF6, have relatively low atmospheric concentrations but
the total radiative forcing due to these gases is increasing rapidly;
these gases are almost entirely anthropogenic in origin.
    Historic data show that current atmospheric concentrations of the
two most important directly emitted, long-lived GHGs (CO2
and CH4) are well above the natural range of atmospheric
concentrations compared to at least the last 650,000 years. Atmospheric
GHG concentrations have been increasing because anthropogenic emissions
have been outpacing the rate at which GHGs are removed from the
atmosphere by natural processes over timescales of decades to
centuries.
(2) Observed Effects Associated With Global Elevated Concentrations of
GHGs
    Greenhouse gases, at current (and projected) atmospheric
concentrations, remain well below published exposure thresholds for any
direct adverse health effects and are not expected to pose exposure
risks (i.e., breathing/inhalation).
    The global average net effect of the increase in atmospheric GHG
concentrations, plus other human activities (e.g., land-use change and
aerosol emissions), on the global energy balance since 1750 has been
one of warming. This total net heating effect, referred to as forcing,
is estimated to be +1.6 (+0.6 to +2.4) watts per square meter (W/
m2), with much of the range surrounding this estimate due to
uncertainties about the cooling and warming effects of aerosols.
However, as aerosol forcing has more regional variability than the
well-mixed, long-lived GHGs, the global average might not capture some
regional effects. The combined radiative forcing due to the cumulative
(i.e., 1750 to 2005) increase in atmospheric concentrations of
CO2, CH4, and N2O is estimated to be
+2.30 (+2.07 to +2.53) W/m2. The rate of increase in
positive radiative forcing due to these three GHGs during the
industrial era is very likely to have been unprecedented in more than
10,000 years.
    Warming of the climate system is unequivocal, as is now evident
from observations of increases in global average air and ocean
temperatures, widespread melting of snow and ice, and rising global
average sea level. Global mean surface temperatures have risen by 1.3
 0.32 [deg]F (0.74 [deg]C  0.18 [deg]C) over
the last 100 years. Eight of the 10 warmest years on record have
occurred since 2001. Global mean surface temperature was higher during
the last few decades of the 20th century than during any comparable
period during the preceding four centuries.
    Most of the observed increase in global average temperatures since
the mid-20th century is very likely due to the observed increase in
anthropogenic GHG concentrations. Climate model simulations suggest
natural forcing alone (i.e., changes in solar irradiance) cannot
explain the observed warming.
    U.S. temperatures also warmed during the 20th and into the 21st
century; temperatures are now approximately 1.3 [deg]F (0.7 [deg]C)
warmer than at the start of the 20th century, with an increased rate of
warming over the past 30 years. Both the IPCC \218\ and the CCSP
reports attributed recent North American warming to elevated GHG
concentrations. In the CCSP (2008) report,\219\ the authors find that
for North America, ``more than half of this warming [for the period
1951-2006] is likely the result of human-caused greenhouse gas forcing
of climate change.''
---------------------------------------------------------------------------

    \218\ Hegerl, G.C. et al. (2007) Understanding and Attributing
Climate Change. In: Climate Change 2007: The Physical Science Basis.
Contribution of Working Group I to the Fourth Assessment Report of
the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin,
M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor, and H.L.
Miller (eds.)]. Cambridge University Press, Cambridge, United
Kingdom and New York, NY, USA.
    \219\ CCSP (2008) Reanalysis of Historical Climate Data for Key
Atmospheric Features: Implications for Attribution of Causes of
Observed Change. A Report by the U.S. Climate Change Science Program
and the Subcommittee on Global Change Research [Randall Dole, Martin
Hoerling, and Siegfried Schubert (eds.)]. National Oceanic and
Atmospheric Administration, National Climatic Data Center,
Asheville, NC, 156 pp.
---------------------------------------------------------------------------

    Observations show that changes are occurring in the amount,
intensity, frequency and type of precipitation. Over the contiguous
United States, total annual precipitation increased by 6.1% from 1901
to 2008. It is likely that there have been increases in the number of
heavy precipitation events within many land regions, even in those
where there has been a reduction in total precipitation amount,
consistent with a warming climate.
    There is strong evidence that global sea level gradually rose in
the 20th century and is currently rising at an increased rate. It is
not clear whether the increasing rate of sea level rise is a reflection
of short-term variability or an increase in the longer-term trend.
Nearly all of the Atlantic Ocean shows sea level rise during the last
50 years with the rate of rise reaching a maximum (over 2 millimeters
[mm] per year) in a band along the U.S. east coast running east-
northeast.
    Satellite data since 1979 show that annual average Arctic sea ice
extent has shrunk by 4.1% per decade. The size and speed of recent
Arctic summer sea ice loss is highly anomalous relative to the previous
few thousands of years.

    Widespread changes in extreme temperatures have been observed in
the last 50 years across all world regions, including the United
States. Cold days, cold nights, and frost have become less frequent,
while hot days, hot nights, and heat waves have become more frequent.
    Observational evidence from all continents and most oceans shows
that many natural systems are being affected by regional climate
changes, particularly temperature increases. However, directly
attributing specific regional changes in climate to emissions of GHGs
from human activities is difficult, especially for precipitation.
    Ocean CO2 uptake has lowered the average ocean pH
(increased acidity) level by approximately 0.1 since 1750. Consequences
for marine ecosystems can include reduced calcification by shell-
forming organisms, and in the longer term, the dissolution of carbonate
sediments.
    Observations show that climate change is currently affecting U.S.
physical and biological systems in significant ways. The consistency of
these observed changes in physical and biological systems and the
observed significant warming likely cannot be explained entirely due to
natural variability or other confounding non-climate factors.
(3) Projections of Future Climate Change With Continued Increases in
Elevated GHG Concentrations
    Most future scenarios that assume no explicit GHG mitigation
actions (beyond those already enacted) project increasing global GHG
emissions over the century, with climbing GHG concentrations. Carbon
dioxide is expected to remain the dominant anthropogenic GHG over the
course of the 21st century. The radiative forcing associated with the
non-CO2 GHGs is still significant and increasing over time.
    Future warming over the course of the 21st century, even under
scenarios of low-emission growth, is very likely to be greater than
observed warming over the past century. According to climate model
simulations summarized by the IPCC,\220\ through about 2030, the global
warming rate is affected little by the choice of different future
emissions scenarios. By the end of the 21st century, projected average
global warming (compared to average temperature around 1990) varies
significantly depending on the emission scenario and climate
sensitivity assumptions, ranging from 3.2 to 7.2 [deg]F (1.8 to 4.0
[deg]C), with an uncertainty range of 2.0 to 11.5 [deg]F (1.1 to 6.4
[deg]C).
---------------------------------------------------------------------------

    \220\ Meehl, G.A. et al. (2007) Global Climate Projections. In:
Climate Change 2007: The Physical Science Basis. Contribution of
Working Group I to the Fourth Assessment Report of the
Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M.
Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller
(eds.)]. Cambridge University Press, Cambridge, United Kingdom and
New York, NY, USA.
---------------------------------------------------------------------------

    All of the United States is very likely to warm during this
century, and most areas of the United States are expected to warm by
more than the global average. The largest warming is projected to occur
in winter over northern parts of Alaska. In western, central and
eastern regions of North America, the projected warming has less
seasonal variation and is not as large, especially near the coast,
consistent with less warming over the oceans.
    It is very likely that heat waves will become more intense, more
frequent, and longer lasting in a future warm climate, whereas cold
episodes are projected to decrease significantly.
    Increases in the amount of precipitation are very likely in higher
latitudes, while decreases are likely in most subtropical latitudes and
the southwestern United States, continuing observed patterns. The mid-
continental area is expected to experience drying during summer,
indicating a greater risk of drought.
    Intensity of precipitation events is projected to increase in the
United States and other regions of the world. More intense
precipitation is expected to increase the risk of flooding and result
in greater runoff and erosion that has the potential for adverse water
quality effects.
    It is likely that hurricanes will become more intense, with
stronger peak winds and more heavy precipitation associated with
ongoing increases of tropical sea surface temperatures. Frequency
changes in hurricanes are currently too uncertain for confident
projections.
    By the end of the century, global average sea level is projected by
IPCC \221\ to rise between 7.1 and 23 inches (18 and 59 centimeter
[cm]), relative to around 1990, in the absence of increased dynamic ice
sheet loss. Recent rapid changes at the edges of the Greenland and West
Antarctic ice sheets show acceleration of flow and thinning. While an
understanding of these ice sheet processes is incomplete, their
inclusion in models would likely lead to increased sea level
projections for the end of the 21st century.
---------------------------------------------------------------------------

    \221\ IPCC (2007) Summary for Policymakers. In: Climate Change
2007: The Physical Science Basis. Contribution of Working Group I to
the Fourth Assessment Report of the Intergovernmental Panel on
Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M.
Marquis, K.B. Averyt, M. Tignor and H.L. Miller (eds.)]. Cambridge
University Press, Cambridge, United Kingdom and New York, NY, USA.
---------------------------------------------------------------------------

    Sea ice extent is projected to shrink in the Arctic under all IPCC
emissions scenarios.
(4) Projected Risks and Impacts Associated With Future Climate Change
    Risk to society, ecosystems, and many natural Earth processes
increase with increases in both the rate and magnitude of climate
change. Climate warming may increase the possibility of large, abrupt
regional or global climatic events (e.g., disintegration of the
Greenland Ice Sheet or collapse of the West Antarctic Ice Sheet). The
partial deglaciation of Greenland (and possibly West Antarctica) could
be triggered by a sustained temperature increase of 2 to 7 [deg]F (1 to
4[deg] C) above 1990 levels. Such warming would cause a 13 to 20 feet
(4 to 6 meter) rise in sea level, which would occur over a time period
of centuries to millennia.
    The CCSP \222\ reports that climate change has the potential to
accentuate the disparities already evident in the American health care
system, as many of the expected health effects are likely to fall
disproportionately on the poor, the elderly, the disabled, and the
uninsured. The IPCC \223\ states with very high confidence that climate
change impacts on human health in U.S. cities will be compounded by
population growth and an aging population.
---------------------------------------------------------------------------

    \222\ Ebi, K.L., J. Balbus, P.L. Kinney, E. Lipp, D. Mills, M.S.
O'Neill, and M. Wilson (2008) Effects of Global Change on Human
Health. In: Analyses of the effects of global change on human health
and welfare and human systems. A Report by the U.S. Climate Change
Science Program and the Subcommittee on Global Change Research.
[Gamble, J.L. (ed.), K.L. Ebi, F.G. Sussman, T.J. Wilbanks,
(Authors)]. U.S. Environmental Protection Agency, Washington, DC,
USA, pp. 2-1 to 2-78.
    \223\ Field, C.B. et al. (2007) North America. In: Climate
Change 2007: Impacts, Adaptation and Vulnerability. Contribution of
Working Group II to the Fourth Assessment Report of the
Intergovernmental Panel on Climate Change [M.L. Parry, O.F.
Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson
(eds.)]. Cambridge University Press, Cambridge, United Kingdom and
New York, NY, USA.
---------------------------------------------------------------------------

    Severe heat waves are projected to intensify in magnitude and
duration over the portions of the United States where these events
already occur, with potential increases in mortality and morbidity,
especially among the elderly, young, and frail.
    Some reduction in the risk of death related to extreme cold is
expected. It is not clear whether reduced mortality from cold will be
greater or less than increased heat-related mortality in the United
States due to climate change.

    Increases in regional ozone pollution relative to ozone levels
without climate change are expected due to higher temperatures and
weaker circulation in the United States and other world cities relative
to air quality levels without climate change. Climate change is
expected to increase regional ozone pollution, with associated risks in
respiratory illnesses and premature death. In addition to human health
effects, tropospheric ozone has significant adverse effects on crop
yields, pasture and forest growth, and species composition. The
directional effect of climate change on ambient particulate matter
levels remains uncertain.
    Within settlements experiencing climate change, certain parts of
the population may be especially vulnerable; these include the poor,
the elderly, those already in poor health, the disabled, those living
alone, and/or indigenous populations dependent on one or a few
resources. Thus, the potential impacts of climate change raise
environmental justice issues.
    The CCSP \224\ concludes that, with increased CO2 and
temperature, the life cycle of grain and oilseed crops will likely
progress more rapidly. But, as temperature rises, these crops will
increasingly begin to experience failure, especially if climate
variability increases and precipitation lessens or becomes more
variable. Furthermore, the marketable yield of many horticultural crops
(e.g., tomatoes, onions, fruits) is very likely to be more sensitive to
climate change than grain and oilseed crops.
---------------------------------------------------------------------------

    \224\ Backlund, P., A. Janetos, D.S. Schimel, J. Hatfield, M.G.
Ryan, S.R. Archer, and D. Lettenmaier (2008) Executive Summary. In:
The Effects of Climate Change on Agriculture, Land Resources, Water
Resources, and Biodiversity in the United States. A Report by the
U.S. Climate Change Science Program and the Subcommittee on Global
Change Research. Washington, DC., USA, 362 pp.
---------------------------------------------------------------------------

    Higher temperatures will very likely reduce livestock production
during the summer season in some areas, but these losses will very
likely be partially offset by warmer temperatures during the winter
season.
    Cold-water fisheries will likely be negatively affected; warm-water
fisheries will generally benefit; and the results for cool-water
fisheries will be mixed, with gains in the northern and losses in the
southern portions of ranges.
    Climate change has very likely increased the size and number of
forest fires, insect outbreaks, and tree mortality in the interior
West, the Southwest, and Alaska, and will continue to do so. Over North
America, forest growth and productivity have been observed to increase
since the middle of the 20th century, in part due to observed climate
change. Rising CO2 will very likely increase photosynthesis
for forests, but the increased photosynthesis will likely only increase
wood production in young forests on fertile soils. The combined effects
of expected increased temperature, CO2, nitrogen deposition,
ozone, and forest disturbance on soil processes and soil carbon storage
remain unclear.
    Coastal communities and habitats will be increasingly stressed by
climate change impacts interacting with development and pollution. Sea
level is rising along much of the U.S. coast, and the rate of change
will very likely increase in the future, exacerbating the impacts of
progressive inundation, storm-surge flooding, and shoreline erosion.
Storm impacts are likely to be more severe, especially along the Gulf
and Atlantic coasts. Salt marshes, other coastal habitats, and
dependent species are threatened by sea level rise, fixed structures
blocking landward migration, and changes in vegetation. Population
growth and rising value of infrastructure in coastal areas increases
vulnerability to climate variability and future climate change.
    Climate change will likely further constrain already over-allocated
water resources in some regions of the United States, increasing
competition among agricultural, municipal, industrial, and ecological
uses. Although water management practices in the United States are
generally advanced, particularly in the West, the reliance on past
conditions as the basis for current and future planning may no longer
be appropriate, as climate change increasingly creates conditions well
outside of historical observations. Rising temperatures will diminish
snowpack and increase evaporation, affecting seasonal availability of
water. In the Great Lakes and major river systems, lower water levels
are likely to exacerbate challenges relating to water quality,
navigation, recreation, hydropower generation, water transfers, and
binational relationships. Decreased water supply and lower water levels
are likely to exacerbate challenges relating to aquatic navigation in
the United States.
    Higher water temperatures, increased precipitation intensity, and
longer periods of low flows will exacerbate many forms of water
pollution, potentially making attainment of water quality goals more
difficult. As waters become warmer, the aquatic life they now support
will be replaced by other species better adapted to warmer water. In
the long term, warmer water and changing flow may result in
deterioration of aquatic ecosystems.
    Ocean acidification is projected to continue, resulting in the
reduced biological production of marine calcifiers, including corals.
    Climate change is likely to affect U.S. energy use and energy
production and physical and institutional infrastructures. It will also
likely interact with and possibly exacerbate ongoing environmental
change and environmental pressures in settlements, particularly in
Alaska where indigenous communities are facing major environmental and
cultural impacts. The U.S. energy sector, which relies heavily on water
for hydropower and cooling capacity, may be adversely impacted by
changes to water supply and quality in reservoirs and other water
bodies. Water infrastructure, including drinking water and wastewater
treatment plants, and sewer and stormwater management systems, will be
at greater risk of flooding, sea level rise and storm surge, low flows,
and other factors that could impair performance.
    Disturbances such as wildfires and insect outbreaks are increasing
in the United States and are likely to intensify in a warmer future
with warmer winters, drier soils, and longer growing seasons. Although
recent climate trends have increased vegetation growth, continuing
increases in disturbances are likely to limit carbon storage,
facilitate invasive species, and disrupt ecosystem services.
    Over the 21st century, changes in climate will cause species to
shift north and to higher elevations and fundamentally rearrange U.S.
ecosystems. Differential capacities for range shifts and constraints
from development, habitat fragmentation, invasive species, and broken
ecological connections will alter ecosystem structure, function, and
services.
(5) Present and Projected U.S. Regional Climate Change Impacts
    Climate change impacts will vary in nature and magnitude across
different regions of the United States.
    Sustained high summer temperatures, heat waves, and declining air
quality are

projected in the Northeast,\225\ Southeast,\226\ Southwest,\227\ and
Midwest.\228\ Projected climate change would continue to cause loss of
sea ice, glacier retreat, permafrost thawing, and coastal erosion in
Alaska.
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    \225\ Northeast includes West Virginia, Maryland, Delaware,
Pennsylvania, New Jersey, New York, Connecticut, Rhode Island,
Massachusetts, Vermont, New Hampshire, and Maine.
    \226\ Southeast includes Kentucky, Virginia, Arkansas,
Tennessee, North Carolina, South Carolina, southeast Texas,
Louisiana, Mississippi, Alabama, Georgia, and Florida.
    \227\ Southwest includes California, Nevada, Utah, western
Colorado, Arizona, New Mexico (except the extreme eastern section),
and southwest Texas.
    \228\ The Midwest includes Minnesota, Wisconsin, Michigan, Iowa,
Illinois, Indiana, Ohio, and Missouri.
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    Reduced snowpack, earlier spring snowmelt, and increased likelihood
of seasonal summer droughts are projected in the Northeast,
Northwest,\229\ and Alaska. More severe, sustained droughts and water
scarcity are projected in the Southeast, Great Plains,\230\ and
Southwest.
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    \229\ The Northwest includes Washington, Idaho, western Montana,
and Oregon.
    \230\ The Great Plains includes central and eastern Montana,
North Dakota, South Dakota, Wyoming, Nebraska, eastern Colorado,
Nebraska, Kansas, extreme eastern New Mexico, central Texas, and
Oklahoma
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    The Southeast, Midwest, and Northwest in particular are expected to
be impacted by an increased frequency of heavy downpours and greater
flood risk.
    Ecosystems of the Southeast, Midwest, Great Plains, Southwest,
Northwest, and Alaska are expected to experience altered distribution
of native species (including local extinctions), more frequent and
intense wildfires, and an increase in insect pest outbreaks and
invasive species.
    Sea level rise is expected to increase storm surge height and
strength, flooding, erosion, and wetland loss along the coasts,
particularly in the Northeast, Southeast, and islands.
    Warmer water temperatures and ocean acidification are expected to
degrade important aquatic resources of islands and coasts such as coral
reefs and fisheries.
    A longer growing season, low levels of warming, and fertilization
effects of carbon dioxide may benefit certain crop species and forests,
particularly in the Northeast and Alaska. Projected summer rainfall
increases in the Pacific islands may augment limited freshwater
supplies. Cold-related mortality is projected to decrease, especially
in the Southeast. In the Midwest in particular, heating oil demand and
snow-related traffic accidents are expected to decrease.
    Climate change impacts in certain regions of the world may
exacerbate problems that raise humanitarian, trade, and national
security issues for the United States. The IPCC \231\ identifies the
most vulnerable world regions as the Arctic, because of the effects of
high rates of projected warming on natural systems; Africa, especially
the sub-Saharan region, because of current low adaptive capacity as
well as climate change; small islands, due to high exposure of
population and infrastructure to risk of sea level rise and increased
storm surge; and Asian mega-deltas, such as the Ganges-Brahmaputra and
the Zhujiang, due to large populations and high exposure to sea level
rise, storm surge and river flooding. Climate change has been described
as a potential threat multiplier with regard to national security
issues.
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    \231\ Parry, M.L. et al. (2007) Technical Summary. In: Climate
Change 2007: Impacts, Adaptation and Vulnerability. Contribution of
Working Group II to the Fourth Assessment Report of the
Intergovernmental Panel on Climate Change [M.L. Parry, O.F.
Canziani, J.P. Palutikof, P.J. van der Linden, and C.E. Hanson
(eds.)], Cambridge University Press, Cambridge, United Kingdom, pp.
23S78.
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E. Changes in Atmospheric CO2 Concentrations, Global Mean
Temperature, Sea Level Rise, and Ocean pH Associated with the
Proposal's GHG Emissions Reductions

    EPA examined \232\ the reductions in CO2 and other GHGs
associated with this proposal and analyzed the projected effects on
atmospheric CO2 concentrations, global mean surface
temperature, sea level rise, and ocean pH which are common variables
used as indicators of climate change. The analysis projects that the
preferred alternative of this proposal will reduce atmospheric
concentrations of CO2, global climate warming and sea level
rise. Although the projected reductions and improvements are small in
overall magnitude by themselves, they are quantifiable and would
contribute to reducing the risks associated with climate change.
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    \232\ Using the Model for the Assessment of Greenhouse Gas
Induced Climate Change (MAGICC) 5.3v2, http://www.cgd.ucar.edu/cas/
wigley/magicc/), EPA estimated the effects of this proposal's
greenhouse gas emissions reductions on global mean temperature and
sea level. Please refer to Chapter 8.4 of the RIA for additional
information.
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    EPA determines that the projected reductions in atmospheric
CO2, global mean temperature and sea level rise are
meaningful in the context of this proposal. In addition, EPA has
conducted an analysis to evaluate the projected changes in ocean pH in
the context of the changes in emissions from this proposal. The results
for projected atmospheric CO2 concentrations are estimated
to be reduced by 0.693 to 0.784 part per million by volume (ppmv)
(average of 0.732 ppmv), global mean temperature is estimated to be
reduced by 0.002 to 0.004[deg]C, sea-level rise is projected to be
reduced by approximately 0.012-0.048 cm based on a range of climate
sensitivities, and ocean pH will increase by 0.0003 pH units by 2100.
(1) Estimated Projected Reductions in Atmospheric CO2
Concentration, Global Mean Surface Temperatures, Sea Level Rise, and
Ocean pH
    EPA estimated changes in the atmospheric CO2
concentration, global mean temperature, and sea level rise out to 2100
resulting from the emissions reductions in this proposal using the GCAM
(Global Change Assessment Model, formerly MiniCAM), integrated
assessment model \233\ coupled with the Model for the Assessment of
Greenhouse Gas Induced Climate Change (MAGICC, version 5.3v2).\234\
GCAM was used to create the globally and temporally consistent set of
climate relevant variables required for running MAGICC. MAGICC was then
used to estimate the projected change in these variables over time.
Given the magnitude of the estimated emissions reductions associated
with the rule, a simple climate model such as MAGICC is reasonable for
estimating the atmospheric and climate response. This widely-used, peer
reviewed modeling tool was also used to project temperature and sea
level rise under different emissions scenarios in the Third and Fourth
Assessments of the IPCC.
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    \233\ GCAM is a long-term, global integrated assessment model of
energy, economy, agriculture and land use, that considers the
sources of emissions of a suite of GHG's, emitted in 14 globally
disaggregated regions, the fate of emissions to the atmosphere, and
the consequences of changing concentrations of greenhouse related
gases for climate change. GCAM begins with a representation of
demographic and economic developments in each region and combines
these with assumptions about technology development to describe an
internally consistent representation of energy, agriculture, land-
use, and economic developments that in turn shape global emissions.
    Brenkert A, S. Smith, S. Kim, and H. Pitcher, 2003: Model
Documentation for the MiniCAM. PNNL-14337, Pacific Northwest
National Laboratory, Richland, Washington.
    \234\ Wigley, T.M.L. 2008. MAGICC 5.3.v2 User Manual. UCAR--
Climate and Global Dynamics Division, Boulder, Colorado. http://
www.cgd.ucar.edu/cas/wigley/magicc/.
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    The integrated impact of the following pollutant and greenhouse gas
emissions changes are considered: CO2, CH4,
N2O, NOX, CO2 and SO2, and
volatile organic compounds (VOC). For CO, SO2, and
NOX, emissions reductions were estimated for 2018, 2030, and
2050 (provided in Section VII.A). For CO2, CH4,
and N2O an annual time-series of

(upstream + downstream) emissions reductions estimated from the
proposal were input directly. The GHG emissions reductions, from
Section VI.C, were applied as net reductions to a global reference case
(or baseline) emissions scenario in GCAM to generate an emissions
scenario specific to this proposal. EPA linearly scaled emissions
reductions between a zero input value in 2013 and the value supplied
for 2018 to produce the reductions for 2014-2018. A similar scaling was
used for 2019-2029 and 2031-2050. The emissions reductions past 2050
were scaled with total U.S. road transportation fuel consumption from
the GCAM reference scenario. Road transport fuel consumption past 2050
does not change significantly and thus emissions reductions remain
relatively constant from 2050 through 2100. Specific details about the
reference case scenario and how the emissions reductions were applied
to generate the scenario can be found in the proposal's RIA, Chapter
8.4.
    MAGICC is a global model and is primarily concerned with climate,
therefore the impact of short-lived climate forcing agents (e.g.,
O3) are not explicitly simulated as in regional air quality
models. While many precursors related to short-lived climate forcers
such as ozone are considered, MAGICC simulates the longer term effect
on climate from long-lived GHGs. The impacts to ground-level ozone and
other non-GHGs are discussed in Section VII of this proposal and the
draft RIA Chapter 8.2. Some aerosols, such as black carbon, cause a
positive forcing or warming effect by absorbing incoming solar
radiation. There remain some significant scientific uncertainties about
black carbon's total climate effect,\235\ as well as concerns about how
to treat the short-lived black carbon emissions alongside the long-
lived, well-mixed greenhouse gases in a common framework (e.g., what
are the appropriate metrics to compare the warming and/or climate
effects of the different substances, given that, unlike greenhouse
gases, the magnitude of aerosol effects can vary immensely with
location and season of emissions). Further, estimates of the direct
radiative forcing of individual species are less certain than the total
direct aerosol radiative forcing.
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    \235\ The range of uncertainty in the current magnitude of black
carbon's climate forcing effect is evidenced by the ranges presented
by the IPCC Fourth Assessment Report (2007) and the more recent
study by Ramanathan, V. and Carmichael, G. (2008) Global and
regional climate changes due to black carbon. Nature Geoscience,
1(4): 221-227.
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    There is no single accepted methodology for transforming black
carbon emissions into temperature change or CO2eq emissions.
The interaction of black carbon (and other co-emitted aerosol species)
with clouds is especially poorly quantified, and this factor is key to
any attempt to estimate the net climate impacts of black carbon. While
black carbon is likely to be an important contributor to climate
change, it would be premature to include quantification of black carbon
climate impacts in an analysis of the proposed standards at this time.
    Changes in atmospheric CO2 concentration, global mean
temperature, and sea level rise for both the reference case and the
emissions scenarios associated with this proposal were computed using
MAGICC. To calculate the reductions in the atmospheric CO2
concentrations as well as in temperature and sea level resulting from
this proposal, the output from the policy scenario associated with the
preferred approach of this proposal was subtracted from an existing
Global Change Assessment Model (GCAM, formerly MiniCAM) reference
emission scenario. To capture some key uncertainties in the climate
system with the MAGICC model, changes in atmospheric CO2,
global mean temperature and sea level rise were projected across the
most current IPCC range of climate sensitivities which ranges from 1.5
[deg]C to 6.0 [deg]C.\236\ This range reflects the uncertainty for
equilibrium climate sensitivity for how much global mean temperature
would rise if the concentration of carbon dioxide in the atmosphere
were to double. The information for this range come from constraints
from past climate change on various time scales, and the spread of
results for climate sensitivity from ensembles of models.\237\ Details
about this modeling analysis can be found in the draft RIA Chapter 8.4.
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    \236\ In IPCC reports, equilibrium climate sensitivity refers to
the equilibrium change in the annual mean global surface temperature
following a doubling of the atmospheric equivalent carbon dioxide
concentration. The IPCC states that climate sensitivity is
``likely'' to be in the range of 2 [deg]C to 4.5 [deg]C, ``very
unlikely'' to be less than 1.5 [deg]C, and ``values substantially
higher than 4.5[deg] C cannot be excluded.'' IPCC WGI, 2007, Climate
Change 2007--The Physical Science Basis, Contribution of Working
Group I to the Fourth Assessment Report of the IPCC, http://
www.ipcc.ch/.
    \237\ Meehl, G.A. et al. (2007) Global Climate Projections. In:
Climate Change 2007: The Physical Science Basis. Contribution of
Working Group I to the Fourth Assessment Report of the
Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M.
Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller
(eds.)]. Cambridge University Press, Cambridge, United Kingdom and
New York, NY, USA.
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    The results of this modeling, summarized in Table VI-8, show small
but quantifiable reductions in atmospheric CO2
concentrations, projected global mean temperature and sea level
resulting from this proposal, across all climate sensitivities. As a
result of the emission reductions from the proposed standards for this
proposal, the atmospheric CO2 concentration is projected to
be reduced by an average of 0.732 ppmv, the global mean temperature is
projected to be reduced by approximately 0.002-0.004 [deg]C by 2100,
and global mean sea level rise is projected to be reduced by
approximately 0.012-0.050 cm by 2100. The range of reductions in global
mean temperature and sea level rise is larger because CO2
concentrations are not tightly coupled to climate sensitivity, whereas
the magnitude of temperature change response to CO2 changes
(and therefore sea level rise) is tightly coupled to climate
sensitivity in the MAGICC model.

[GRAPHIC] [TIFF OMITTED] TP30NO10.054

    The reductions are small relative to the IPCC's 2100 ``best
estimates'' \238\ for global mean temperature increases (1.1--6.4
[ordm]C) and sea level rise (0.18-0.59m) for all global GHG emissions
sources for a range of emissions scenarios.\239\ These ``best
estimates'' are assessed from a hierarchy of models that encompass a
simple climate model, several Earth Models of Intermediate Complexity,
and a large number of Atmosphere-Ocean Global Circulation Models and
are based on the six major scenarios described in the Special Report on
Emissions Scenarios, not including dynamical ice sheet behavior that
would lead to an increase in sea level rise. Further discussion of
EPA's modeling analysis is found in the draft RIA, Chapter 8.
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    \238\ IPCC's ``best estimates'' at the end of the 21st century
from Table TS.6 in the Technical Summary: Contribution of Working
Group I (Solomon et al., 2007).
    \239\ IPCC (2007) Climate Change 2007: The Physical Science
Basis. Contribution of Working Group I to the Fourth Assessment
Report of the Intergovernmental Panel on Climate Change [Solomon,
S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor,
and H.L. Miller (eds.)]. Cambridge University Press, Cambridge,
United Kingdom and New York, NY, USA.
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    EPA used the Program CO2SYS,\240\ version 1.05 to estimate
projected changes in ocean pH for tropical waters based on the
atmospheric CO2 concentration change (reduction) resulting
from this proposal. The program performs calculations relating
parameters of the CO2 system in seawater. EPA used the
program to calculate ocean pH as a function of atmospheric
CO2 concentrations, among other specified input conditions.
Based on the projected atmospheric CO2 concentration
reductions (0.731 ppmv by 2100 for a climate sensitivity of 3.0) that
would result from this proposal, the program calculates an increase in
ocean pH of 0.0003 pH units. Thus, this analysis indicates the
projected decrease in atmospheric CO2 concentrations from
the preferred approach associated with this proposal would result in an
increase in ocean pH. For additional validation, results were generated
from the atmospheric CO2 concentration change for each
climate sensitivity case (1.5 to 6.0) and using different known
constants from the literature. A comprehensive discussion of the
modeling analysis associated with ocean pH is provided in the draft
RIA, Chapter 8.
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    \240\ Lewis, E., and D. W. R. Wallace. 1998. Program Developed
for CO2 System Calculations. ORNL/CDIAC-105. Carbon
Dioxide Information Analysis Center, Oak Ridge National Laboratory,
U.S. Department of Energy, Oak Ridge, Tennessee.
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(2) Proposal's Effect on Climate
    As a substantial portion of CO2 emitted into the
atmosphere is not removed by natural processes for millennia, each unit
of CO2 not emitted into the atmosphere avoids essentially
permanent climate change on centennial time scales. Reductions in
emissions in the near-term are important in determining long-term
climate stabilization and associated impacts experienced not just over
the next decades but in the coming centuries and millennia.\241\ Though
the magnitude of the avoided climate change projected here is small,
these reductions would represent a reduction in the adverse risks
associated with climate change (though these risks were not formally
estimated for this proposal) across a range of equilibrium climate
sensitivities.
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    \241\ National Research Council (NRC) (2010). Climate