This chapter summarizes the latest information on U. S. greenhouse gas emission trends, from 1990 to 1995 , as presented in the draft EPA report, Inventory of U. S. Greenhouse Gas Emissions and Sinks: 1990 1995. To ensure that the U. S. emissions inventory is comparable to those of other FCCC signatory countries, the estimates presented here were calculated using baseline methodologies similar to those recom mended in Volumes 1 3 of the IPCC Guidelines for National Greenhouse Gas Inven tories (IPCC/ OECD/ IEA/ UNEP 1995). For U. S. emission sources related to energy consumption, forest sinks, and some CH2ources, the IPCC default methodologies were expanded, resulting in a more comprehensive procedure for estimating U. S. emissions. Details on how these estimates were developed are available in the 1995 Inventory of U. S. Greenhouse Gas Emissions and Sinks: 1990 1994 (U. S. EPA 1995) and i n the L! pcomir? g editicn.

This document has been reformated to facilitate electronic distribution.

Greenhouse Gas Inventory  3 ... Recent Trends in US. Greenhouse Gas Emissions the atmosphere, the' cent atmospheric buildup is largely the result of human activities. Since 1800, atmospheric concentrations of these greenhouse gases have increased by 30, 145, and 15 percent,

6 Greenhouse gasesjnclude water vapor, carbon respectively (Ipcc 1996). This buildup has altered dioxide (CO,), methane (Cy), nitrous oxide (yo), the Of the earth's atmosphere, and may and ozone (OJ. Chlorofluorocarbons (CFCs), a affect future global climate.

family of human made compounds, and other com Beginning in the 195O's, the use of CFCs in pounds such as hydrofluorocarbons (HFCs) and creased by nearly 10 percent L1 )` ear, u n t i l the mid perfluorinated carbons (PFCs) are also greenhouse 1980's when international concern about Ozone gases. depletion led to the signing of the Montreal Protocol.

Other nongreenhouse, radiatively important Since then, the consumption of CFCs has rapidly gases  such as carbon monoxide (CO), oxides of declined as they are phased Ollt. In contrast, LlSe O f nitrogen (NOx), and nonmethane volatile organic CFC substitutes is expected to grow significantly. compounds (NMVOCs)  contribute indirectly to Figure 3 1 and Table 3 1 summarize the current the greenhouse effect. These are commonly referred U. S. greenhouse gas emissions inl'entory for 1990 to as "tropospheric ozone precursors" because they 4 95. They present the estimated sources and sinks in influence the rate at which ozone and other gases are millions of metric tons Of carbon equivalent .

created and destroyed in the atmosphere. For conve (MMTCE), which accounts for the gases' global nience, all gases discussed in this chapter are generi warming potentials. cally referred to as "greenhouse gases" (unless The growth in U. S. greenhouse gas emissions has otherwise noted). been erratic from 1990 to 1995. Emissions from Although CO,, CH,, and N$) occur naturally in anthropogenic Sources in dropped in 1991, increaEd steadily through 1994, and then slowed down in 1995. Over the five year period, greenhouse gas emissions rose by 5.9 percent, representing Figure 3 I Recent Trends in U. S. Greenhouse Gas Emissions an average annual increase of just Over one (1990 1995) 1800 __.....__...._......._....._._............,............ percent. This trend is largely attributable to changes in total energy consumption resulting 1990s and the subsequent recovery. U. S. 1600 . f r o m t h e economic slowdown in t h e e a r l y .I a, 1400 C  . energy consumption increased at an average  m annual rate of 1.5 percent over the same period 1200 . ' (DOEEIA 1996a). The increase in emissions C from 1993 through 1995 \vas also influenced * creased demand for fossil fwls (DOEEIA s! . * changes in CO, emissions from fossil fuel  *. the five year period. In most cases, emissions 8 .

Lu 0 Ei looo 1 by generally low energy prices, which in

0 u) 800 C 0 Among the inventory's greenhouse gases, . L 600 s consumption had the greatest impact during a f r o m m e t h a n e , N, O, HFCs, PFCs, and sulfur 200 .. hexaflouride (SF,) have rcrnained relatively .O 400 C

constant or have increased slightly. For ex ample, methane emissions increased by just over 4 percent. The rise in HFC, PFC, and SF, El HFCS, PFCS, & SFS since 1990, overa{/ em/ ssions of Nitrous Oxide CO;, have incrsssed, while emissions emissions, although a small portion of the of othergreenhouseandphotcchemically total, is significant because of their extremely [17 Methane importanfgassShave remainedrlek! ile& high global warming potentials and, i n the cases of PFCs and S t , their long atmospheric 0 1990 1997 1992 1993 1994 1995 Carbon Dioxide constant ofd& h&

4  US. Climate Action Report I , . .\ i Recent Trends in U. S. Greenhouse Gas Emissions (1990 1995) ("T s of Carbon Equivalent)

Gasand Source  A . Emissions  Direct and Indirect Effects 1990 1991 1992 1993 _. _. . ". ...... . . .... . .... .

Carbon Dioxide (0 2 ) 1,228 1,213 1,235 1,268 1,291 1,305 Fossil Fuel Combustion 1,336 1,320 1,340 1,370 1,391 1,403 Industrial Processes and Other 17 16 17 18 19 19 ZM (3S' (336 (357 (388 (470 1,422 Forests (sink) ' (125) (123) (122) (120) (119) (117)

Methane (CH?) 170 172 173 171 176 177 Landfills 56 58 58 60 62 64 Agriculture 50 57 52 52 54 55 Coal Mining 24 23 22 20 21 20 Oil and Natural Gas Systems 33 33 34 33 33 33 Other 6 7 ,& 6 6 6 Nitrous Oxide (Nz0) 36 , 37 37 38 39 40 Agriculture 17 17 17 18 18 18 Fossil Fuel Consumption 11 11 12 12 12 12 Industrial Processes 8 8 8 8 9 9 HFCs PFCs SF6 12 12 13 14 17 21 5 5 5 5 7 8 7 7 8 8 8 8 U. S: Emissions 1,583 1,570 1,592 1,624 1,657 1,676 Net U. S, Emissions !: 1,458 1,447 i ,470 1,504 1,538 1,559 *These estimates for the conterminous US for 1990 91 and 1993 95 are interpolated from forest inventories in 1987 and 1992, and projections through 2040. The methodology reflects long term averages rather than specific events in any given year. Note: The totals presented in the summary tables in this chapter may not equal the sum of the individual source categories due to rounding. Nitrous oxide emissions rose by just under 10 percent during the period, primarily for two reasons. First, fertilizer use, which account for approximately 46 percent of total U. S. N, O emissions, increased sigificantly during 1993 95 as farmers planted more acreage and worked to replace nutrients lost i n the 1993 floods. And second, emis sions from other categories grew slightly as the U. S. economy grew. HFCs, PFCs, and SF, emis sions are increasing, along with their expanded use as substitutes for CFCs and other ozone depleting compounds being phased out under the terms of the Montreal Protocol and Clean Air . Act Amendments (IPCC/ OECD/ IEA/ UNEP 1995). Two major contributors to the rise in HFC emissions since 1990 are the use of HFC 134a for mobile air conditioners and the emission of HFC 23 during the production of the refrigerant HCFC 22. The following sections present the anthropogenic sources of greenhouse gas emissions, briefly discuss emis lifetimes. Greenhouse gas emissions were partly sion pathways, summarize the emission estimates, offset by carbon sequestration in forests. and explain the relative importance of emissions the primary greenhouse gases to total U. S. emissions in 1995, with CO, emissions accounted for the largest share. The largest change i n methane emission estimates compared to earlier inventories is in the natural gas sector, where emissions have been Total 1995 US. G r e e n h o u s e G a s Emissions adjusted upward by more than 75 percent due to HFCs improved estimation methods; however, these revised NitrousOxide (1.2%)

emissions have not changed significantly during 1990 95. LarSei landfills, apanded animal popuh tions, and more widespread use of liquid manure management systems increased methane emissions from waste management and agricultural activities. In contrast, improved methane recovery and lower coal production from gassy mines have reduced methane emissions from coal mining. (84.8%) Figure 3 2 illustrates the relative contribution of from each Source category.

Figure 3 2 Methane (2.4%)

(10.6w \ PFCs (O. S%/ J Carbon Dioxide Greenhouse Gas Inventory  5 ~ ~~~~ Box 3 I The Global Warming . .. .. Potential Concept.. . ..

I  ,.. . .. ..

Gases can contribute to the greenhouse effect both directly and indirectly. Direc when the gas itself is a greenhouse gas; indirect radiative forcing occurs when ch transformations of the original gas produce a greenhouse gas, or when a gas infl atmospheric lifetimes of other gases.

The concept of Global Warming Potential (GWP) has been developed to allow scientists and policy makers to compare the ability of each greenhouse gas to trap heat in the atmosphere relative to another gas. C02 was chosen as the reference gas to be consistent with IPCC guidelines (IPCCIOECDIIENUNEP 1995). a All gases in this inventory are presented in units ofmillion metric tonnes of carbon equivalent, or MMTCE. Carbon comprises 12/ 44 of carbon dioxide by weight. The following equation may be used to convert MMTsof emissions of greenhouse gas (GHG) x to MMTCE:

"TCE=(" T of GHGx)( GWP of GHGx)( l2/ 44)

The GWP of a greenhouse gas is the ratio of. global warming, or radiative forcing (both direct and indirect), from one kilogram of a greenhouse gas to one kilogram of C02 over a period of time. While any time period may be selected, this report uses the 1 OO year GWPs recommended by the IPCC and employed for U. S. policy making and reporting purposes (IPCC 1996).

The GWPs of some selected GHGs are shown here. GWPs are not provided for the photochemically important gases CO, Nox, NMVOCs, and SO2 because there is no agreed upon method to estimate their contributions to climate change, and they affect radiative forcing only indirectly (IPCC 1996). Global Warming Potential The higher global waiming potential lower emitting ,greenhouse gases significantly increases their contribulio the greenhouse effect. For example, o 100 year time horizon, nitrous oxid? i times more effective than carbon dioxi trapping heat in. the atmosphere. . .,

GWP .. . .. . .. . . ., . _. . ..

Gas ..

(1 00 Years) Carbon Dioxide 1

Methane , 21 Nitrous Oxide 31 0 HFC 23 1 1,700 HFC 125 2,800 HFC 134a 1,300 HFC I 43a 3,800 HFC 152a 140 HFC 227ea 2,900 HFC 43 1 Omme \ 1,300 CF4 6,500 CZFS 9,200 c4F10 7,000 c6F14 7,400 PFCs/ PFPEs 7,400 SF6 23,900 6  U. S. Climate Action Report Carbon Dioxide Emissions figure 3 3  Sources of U. S. Energy Consumed in 1995 The global carbon cycle is made up 'of large carbon flows andre% eIyoirs. Hundreds of billions of tons of carbon in the form of CQare absorbed by the oceans or trees (sinks) or are emitted to the atmo sphere annually through natural processes (sources). When in equilibrium, carbon fluxes among the various reservoirs are roughly balanced.

has been increasingly compromised. Atmospheric concentrations of CO, have risen about 30 percent, Since the Industrial Revolution, this equilibrium (25%) (38%) Natural Gas Petroroieum Source: .! L S. DOEAEIA 19955 principally because of fossil fuel combustion, which accounts for 99 percent of total U. S. COgmissions (Seki 1995). Changes in land use and forestry activi ties can emit CO,( e. g., through conversion of fwst land to agriculturh or urban use) and can act as a sink for  or absorb  CO, (e.,.., through improved forest management activities).

CO,, while the remainder of this section discusses CO,  emission trends in greater detail. Table 3 2 summarizes US. sources and sinks of The Energy Sector percent of annual U. S. greenhouse gas emissions. Of that share, approximately 85 percent is produced through fossil fuel combustion, and the remaining 15 percent comes from renewable or other energy sources, such as hydropower, biomass, and nuclear energy (Figure 3 3). Energy related activities other than fuel combustion also emit greenhouse gases Energy related activities accoyt for roughly 87 Fossil Fuel Consumption ResidenIial Commercial Industrial Transportation U. S. Territories Fuel Production and Processing 6.2 1.7 Cement Production 38.5 10.5 Lime Production 13.6 3.7 Limestone Consumption 4.4 , ' 1.2 Soda Ash Production and Consumption 5.9 1.6 Carbon Dioxide Manufacture 1.5 0.4 .... .... .. ... ..... I ,.. . . ,. . .... .. ... ... .. .. ..

. ...

Note: The totals provided here do not reflect emissions from bunker fuels used in international transport activities. At its Ninth Session, the Intergovernmental Negotia: ing Comm;:! ee instruc: ed countries to report these emissions separately, and not include them in national totals. U. S. emissions from bunker fuels were zpproximately 22 MMTCE in 1995. (primarily methane), such as those associated with producing, transmit ting, storing, and distributing fossil fuels.

Fossil Fuel Consumption The amount of carbon in fossil fuels vanes significantly by fuel type. For example, coal contains the highest amount of carbon per unit of energy, natural gas has about 45 percent less than coal, and petroleum has about 20 percent less. Carbon dioxide is the most significant GHG emitted in the U. S. Currently, carbon dioxide makes up 85 percent of the total US. GHG emissions and the combustion of fossil fuels accounts for 99 percent of that portion. In 1995, U. S. fossil fuel combustion eniited 1,403 million metric tons of carbon equivalent (MMTCE). Tetal consumption of fossil fuels during 1990 95 increased at an average annual rate of 1.2 percent, primarily because of eco nomic groivth and generally low energy prices.

Greenhouse Gas Inventory  7 ... x , /

*. .I ., /

Overall, emissions from foss Jel consumption energy consumed i n sector comes from petro have increased from 1990 to 1995. While emissions leum based products. Nearly two thirds of the of CO, in 1991 were approximate1y 1.2 percent lou. er emissions result fI'Om gasoline Consumption in than the 1990 baseline level, in 1992 they increased automobiles and other vehicles. The remaining by about 1.6 percent abo. ve the 1991 levels, thus emissions stem from meeting other transportation returning emissions to slightly more than the 1990 demands, including the combustion of diesel fuel for baseline, By 1993, CO, emissions from fossil fuel the trucking industry and jet fuel for aircraft. combustion were approximately 2.5 percent greater Residential and Commercial Sectors. The than i n 1990; in 1994, they were about 4.1 percent residential and commercial Sectors account for about higher than 1990; and in 1995, they were about 5 19 and 16 percent, respectively, of CQemissions percent higher. This trend is largely attributable to frorll fossil fuel consumption, Both s& tors rely changes in total energy consumption resulting from heavily on electricity for meeting energy needs, with the economic slowdown in. the United States i n thc about two thirds to three quarters of their emissions early 1990s and the subsequent recovery. attributable to electricity consumption. End use Despite the continued increase in natural gas and applications include lighting, heating, cooling, and coal consumption in 1995, the total amount of operating appliances. The remaining emissions are petroleum used for energy production declined by .$ largely due to the consumption of nafural gas and oil, about 0.2 percent, as somewhat higher prices for primarily for meeting heating and cooking needs. cruds oil in 1995 led electric utilities and industry to Electric Utilities. The United States relies on decrease their consumption of petroleum by 32 and electricity to meet a significant portion of its energy 1.9 percent, respectively, and to rely more heavily on requirements  e. g., lighting, electric motors, and natural gas, coal, nuclear electric power, and, renew heating and air conditioning. As the largest consum able energy. In contrast, consumption of petroleum ers of U. S. energy (averaging 28 percent), electric increased 1.3 percent in the residential and commer utilities are collectively the largest producers (ap cia1 sectors, and about 1.6 percent in the trsnsporta proximately 3 j percent) of U. S. CO, emissions tion sector.

emissions included steam production for industrial processes, gasoline consump tion for transportation, heating in residen tial and commercial buildings, and generation of electricity. Petroleum products across all sectors of the economy accounted for about 42 percent of total U. S. energy related C0, emis sions; coal, 36 percent; and natural gas, 22 percent. Industrial Sector. Industry accounts for the largest percentage of U. S. emis sions from fossil fuel consumption (Figure 3 4). About two thirds of these emissions result from producing steam and process heat, while the remaining third rzsults from providing electricity for such uses as motors, electric furnaces, ovens, and lighting. Transportation Sector. In the same league as the industrial sector, the trans portation sector accounts for about 31 percent of U S . CO, emissions from fossil fuel consumption. Virtually all of the The energy related sources of CQ . (Figure 3 5).

Ffgue 3 4 and3 5 1995 Sectoral Emissions of C02 from Fossil Fuel Combustion Cwnmercial 15.7% lnduitri+ 7f Mte: In this piechart, .5%) electric utit~ v emisicns 8R distfitutedto each enduseseabracccrdhg to each setofs share d dectricity wnsunption.

Transp crtation i Rsickntial (7%) Ccmrnerciaf I E I Coal ]

.A (5%)

I 0 100 200 300 400 500 MilJon Mdrc Tons Czxbon Equivalent 8  U. S. Climate Action Report ~~ ~~~ '7 The type of energy eleci utilities consume directly affects the volume of CO, emitted. For example, some of this electricity is generated with low emitting technologies, such as nuclear energy,

4 hydropower, or geethermal energy. However, electric utilities rely on coal for over half of their total energy requirements and account for about 87 percent of all coal consumed i n the United States. Consequently, changes i n electricity demand can significantly affect coal consumption and associated CQ emissions.

Fuel Production and Processing at natural gas systems and oil wells. The methane trapped in natural gas systems or oil wells is flared to relieve the rising pressure or to dispose of snlall quantities of gas that are not commercially mark  able. As a result, the carbon contained in the met 1 ane becomes oxidized and forms CO,. In 1995, flaring activities emitted approximately 2 MMTCE, or about 0.1 percent of total U S . Cqemissions. Emissions trends from fuel production and processing are dictated by fossil fuel consumption.

Biomass and Biomass Based Fuel Consumption Biomass fuel is used primarily by the industrial sector in the form of fuel wood and wood waste, while the transportation sector dominates the'use of biomass based fuel, such as ethanol from corn or woody crops. Ethanol and ethanol blends, such as gasohol, are typically used to fuel public transport vehicles. Carbon dioxide is produced via flaring activities Although these fuels do emit C9, their emis sions do not increase total atmospheric CQbecause the biomass resources are consumed on a sustainable basis. For example, fuel wood burned one year but regrown the next only recycles carbon, rather than creating a net increase in total atmospheric carbon. CO, emissions from biomass consumption were approximately 51 MMTCE, with the industrial sector accounting for 72 percent of the emissions, and the residential sector, 25 percent. CQ emissions from ethanol use in the United States have been rising in recent years due to a number of factors, including extension of federal tax exemptions for ethanol production, the Clean Air Act Amendments mandat ing the reduction of mobile source emissions, and the Energy Policy Act of 1992, which established incentives for increasins the use of alternative fueled vehicles. In 1995, total U. S. CQ emissions from ethanol were 2 MMTCE. / , ".

Inc trial Processes Emissions are often produced as a by product of various nonenergy related activities. For example, in the industrial sector raw materials are often chemi cally transformed from one state to another. This transformation often releases such greenhouse gases as CO,. The production processes that emit CO, include cement production, lime production, lime stone consumption (e. g., in iron and steel making), soda ash production and use, and CQmanufacture. Total carbon dioxide emissions from these SOllrCeS were approximately 17.4 MhlTCE in 1995, account ing for about 1 percent of total U. S. Cemissions. In 1995, emissions from these sources were approxi mately 10.5, 3.7, 1.2, 1.6, and 0.4 MMTCE, respec tively, for a total of 17.4 MMTCE, or about one percent of total U. S. Cofmissions. Since 1990, emissions from cement, lime, and CQ manufacturing have increased slightly; emissions from limestone use have fluctuated; while emissions from soda ash production remained constant from 1990 1994 and increased in 1995. *

Cement Production ( . MMTC )

production of clinker, an intermediate product from which finished Portland and masonry cement are made. Specifically, carbon dioxide is created when calcium carbonate (CaCOJ is heated in a cement kiln to form lime and CO, This lime combines with other materials to produce clinker, while the CQis re leased into the atmosphere.

Lime Production ( . MMTC )

and paper manufacturing, and water and sewage treatment. It is manufactured by heating limestone (mostly calcium carbonate  CaCO,) in a kiln, creating calcium oxide (quicklime) and CQ which is normally emitted to the atmosphere.

Soda Ash Production and Consumption

Carbon dioxide is produced primarily during the Lime is used in steel making, construction, pulp ( . MMTC ) Commercial soda ash (sodium carbonate) is used i n many consumer producis, s x h as glass, soap and detergents, paper, textiles, and food. During the manufacturing of these products, natural sources of sodium carbonate are heated and transformed into a crude soda ash, in which CQis generated as a by product. In addition, CO, is released when the soda ash is consumed.

~~~ ~

Greenhouse Gas Inventory  9 "y .,

limestone Consumption ( , h 'C )

variety of industries, including the construction, agriculture, chemical, and metallurgical industries. Fdr example, limestone can be used as a purifier in refining metals. In the case of iron ore, limestone heated i n a blast furnace reacts with impurities i n the iron ore and fuels, generating COqs a by product. Limestone is also used in flue gas desulfurization systems to remove sulfur dioxide from the exhaust gases.

Carbon Dioxide Manufacture ( . MMTC )

economy, including food processing, beverage manufacturing, chemical processing, crude oil products, and a host of industrial and miscellaneous4 applications. For the most part, the CQused in these applications will eventually be released into the atmosphere. Limestone is a basic raw material used by a wide Carbon dioxide is used in many segments of the Changes in Forest Management and Land Use How the Earth's land resources are managed can alter the natural balance of trace gas emissions. ,

Everyday land use decisions include clearing an area of forest to create cropland or pasture, restocking a logged forest, draining a wetland, or allowing .a pasture to revert to a grassland or forest.

(737 million acres) of U. S. land in the contiguous 48 states (USDANSFS 1990), are also an important terrestrial sink for Cq. Because approximately half the dry weight of wood is carbon, as trees add mass to trunks, limbs, and roots, carbon is stored in relatively long lived biomass instead of being released to the atmosphere. Soils and vegetative cover also provide potential sinks for carbon emis sions. Forests, which cover about 295 million hectares In the United States, improved forest manage ment practices and the regeneration of previously cleared forest areas have resulted in a net uptake (sequestration) of carbon in U. S. forest lands. This uptake is an ongoing result of land use changes in previous decades. For example, because of improved agricultural productivity and the widespread use of tractors, the rate of clearing forest land for crop cultivation and pasture slowed greatly in the late 19th century, and by 1920 this practice had all but ceased. As farming expanded in the Midwest and West, large areas of previously cultivated land in the East were n brought out of crop . duction, primarily between 1920 and 1950, and were allowed to revert to forest land or were actively reforested. Since the early 1950s, the managed growth of private forest land in the East has nearly doubled the biomass density there. The 1970s and 1980s saw a resurgence of federally sponsored tree plantins programs (e. g., the Forestry Incentive Program) and soil conservation programs (e.,.., the Conservation Reserve Program), which have focused on reforesting previously harvested lands, improving timber management, combating soil erosion, and converting marginal cropland to forests.

1995 is estimated to have been an uptake of i17 MMTCE (which includes the carbon stored in the U. S. wood product pool and in landfiils). This carbon uptake represents an offset of about S percent of the 199 5 CO, emissions from fossil fuel combustion during this period. The amount of carbon sequestered through changes in U. S. forestry and land use prac tices continues to decline, as the expansion of eastern forest c o v e r s l o w s d o w n .  As a result of these activities, the net CO, flux in Methane Emissions Atmospheric methane (CH,) is an integral component of the greenhouse effect, second only to CO, as an anthropogenic source. Methane's overall contribution to global warming is large because it is estimated to be twenty one times more effective at trapping heat in the atmosphere than CQover a 100 year time horizon (IPCC 1996). Over the last two centuries, methane's concentration in the atmosphere has more than doubled. Scientists believe these atmospheric increases are due largely to increasing emissions from anthropogenic soarces, such as landfills, agricultural activities, fossil fuel combus

FQure 3 6 U. S. Sources of Methane Emissions in 1995 FossilFuel Consurnp~ iofl coal~ dning (2.6%) Wastewater (I i. 5;;) I / Trsatrnen! .

(30.9%) (." IO,

10  US. Climate Action Report / , ., ".

. .~ '# have reduced lan 1 methane emissions by more than 50 percent (6. 'L million metric tons of methane, by Source in 1995 or 35.5 MMTCE).

MMT MIMTCE 11.1 63.5 The agricultural sector accounted for approxi 9.6 54.8 3.6 20.4 mately 31 percent of total US. methane emissions i n Oil andNatural Gas Systems 5.8 33.2 1995, with enteric fermentation i n domestic livestock Fossil 0.8 4.6 (34.9 MMTCE) and manure management (17.1 WastewaterTreatment 0.2 0.9 MMTCE) together accounting for the majority (Figure 3 7). Other agricultural activities contributing TOTAL EMISSIONS 31 .O 377.3 directly to methane emissions include rice cultivation * . ,. . . Agriculture . . ...... ... .... . .. ... ." .  . (2.5 MMTCE) and field burning of agricultural crop Note: All methane emission estimates are preliminary.

* One year data were used to estimate methana emissions from rice wastes (0.04 MMTCE).

cultivationas part of theAgriculturesector. Correspondingvalues for the Between 1990 and 1995, methane emissions Agricultural sector using lPCC recommended three year averages for ricecultivationare: 9.3 MMT and 53.2 MMTCE. from domestic livestock enteric fermentation and manure management increased by about 7 percent '

tion, coal mining, the production and processing of and 1 j percent, respectively. During this Same time natural gas and oil, and wastewater treatment (Table period, methane emissions from rice cultivation 3 3 and Figure 3 6). increased by about 10 percent, while emissions from field burning fluctuated. Several other agricultural Landfills activities, such as ihigation and tillage practices, may Landfills =e the largest single anthropogenic contribute to methane emissions. However, since Source of methane emissions in the United States. Of emissions from these sources are uncertain and are the estimated 3,000 methaneeemitting landfills in the believed to be small the United States has not in United States, 1,300 account for about half ofthe cluded them in the Current inventory. Details on the emissions. emission pathways included in the inventory follow. In an environment where the oxygen content is Enteric Fermentation in Domestic Livestock low or nonexistent, organic materials, such as yard ( .g MMTC waste, household waste, food waste, and paper, are During animal digestion, methane is produced decomposed by bacteria to produce "2, through a process referred to as enteric fermentation, and stabilized organic materials (materials that in which microbes that reside in animal digestive cannot be decomposed further). Methane emissions systems break down the feed consumed by the from landfills are affected by such specific factors as animal. In 1995, fermentation was the waste composition, moisture, and landfill size. of about 20 percent of total U. S. methane emissions, Methane emissions from U. S. landfills in 1995 and about 64 percent of methane emissions from the were 63.5 MMTCE, a slight increase over the 60 MMTCE reported in the previous inventory. Emis sions from U. S. municipal solid waste landfills, Figure 3 7 which received over 59 percent of. the total solid U. S. Sources of Agricultural waste generated in the United States, accounted for Methane Emissions in 1995 about 90 to 95 percent of total landfili emissions, while industrial landfills accounted for the remaining Rice Cultivation waste Bumin_ o 5 to 10 percent. Currently, almost 15 percent of the methane released is recovered for use as energy, compared to 10 percent reported in the last inventory. A regulation promulgated in March 1996 re quires the largest U. S. landfills to collect and com bust t h e i r l a n d f i l l emissions of i3: eric Fernentation nonmethane volatile organic compounds (VOCs). It (a %)

is estimated that by the year 2000, this regulation will Agricultural " ,

Greenhouse Gas Inventory  11 I agricultural sector. This estimate 34.9 MMTCE is the same as that reported in the previous inventory.

Manure Management ( . MMTC )

anaerobic environment produces methane. The most important factor affecting the amount of methane produced is how the manure is managed, since certain types of storage and treatment systems promote an oxygen free environment. In particular, liquid systems tend to produce a significant quantity of methane, whereas solid waste management approaches produce little or no methane. Higher temperatures and moist climatic conditions also promote methane production. Emissions from manure management were about 10 percent of total U. S. methane emissions in1995,, and about 31 percent of methane emissions from the agriculture sector. Liquid based manure management systems accounted for over SO percent of total emissions from animal wastes. The 17.1 MMTCE estimate reported here is slightly above the 13.7 MMTCE reported in the previous inventory because of larger U. S. farm animal populations and expanded use of liquid manure management systems.

Rice Cultivation ( . MMTC )

United States, is grown on flooded fields. The soil's organic matter decomposes under the anaerobic .

conditions created by the flooding, releasing methane to the atmosphere, primarily through the rice plants. In 1995, rice cultivation .was the source of less than 2 percent of total U. S. methane emissions, and about 5 percent of U. S. methane emissions from agricultural sources. Emissions estimates from this source have not changed significantly since 1990.

Field Burning of Agricultural Wastes , The decomposition of organic animal waste in an Most of the world's rice, and all of the rice in the ( . MMTC ) Farming systems produce large quantities of agricultural crop wastes. Disposal systems for these wastes include plowing them back into the field; composting, landfilling, or burning them in the field; using them as a biomass fuel; or selling than in supplemental feed markets. Burning crop residues releases a number of greenhouse gases, including C q , methane, carbon monoxide, nitrous oxide, and oxides of nitrogen. Field burning is not considered to be a net source of carbon dioxide emissions because the CQ released during burning is reabsorbed by crop regrowth during _.

the next growing sez . However, this practice is a net source of emissions for the other gases, since their emissions would not have occurred had the wastes not been combusted. Because field burning is not common in the United States, it was responsible for only 0.02 percent of total U. S. methane emissions in 1995, and 0.07 percent of emissions from the agricultural sector. Estimates of emissions from this source have dropped significantly since the last inventory as a result of new research indicating that a smaller fraction of U. S. crop wastes is burned than previ ously assumed.

Oil and Natural Gas Production and Processing Methane emissions vary greatly from facility to facility. In 1995, an estimated 31.2 MMTCE (or approximately I S percent) of U. S. methane emissions were due to leaks, disruptions, etc., in the operation and maintenance of equipment in the U. S. natural gas system. This figure is `significantly higher than previous estimates because of revised estimation

methods that improved activity factors (i. e., equip ment counts) and emission factors. As a result, natural gas systems are now ranked as the third largest source of U. S. methane emissions. Natural gas is often found in conjunction with oil exploration. Methane is also released during the production, refinement, transportation, and storage of crude oil. During 1995, oil and gas production facilities released 2.0 MMTCE of methane to the atmosphere, representing about one percent of total U. S. methane emissions.

Coal Mining Produced millions of years ago during the formation of coal, methane is trapped within coal seams and surrounding rock strata. The volume of methane released to the atmosphere during coal mining operations depends primarily upon the depth and type of coal being mined. Methane from surface mines is emitted directly coal seam are removed. Because methane in under ground mines is explosive at concentrations of 5 to 15 percent in air, most active underground mines are required to circulate large quantities of air and vent the air into the atmosphere. At some mines, methane recovery systems may supplement these ventilation to ths atizoaphers X thz rock stia; d ovzrlying iiie 12  U. S. Climate Action Report  ,. . ,,

. .

systems to ensure mine saff u. S. recovery of Agricult~ Soil Management and methane has been increasing rn recent years. During Fertilizer Use 1995, coal mining, processing, transportation, and consumption activities produced an estimated 20.4 MMTCE of methzne,.. pr 12 percent of total U. S. methane emissions. This lower estimate is the result of improved mine specific information and expanded methane recovery. In 1995, U. S. consumption of synthetic nitrogen and organic fertilizers accounted for 18.4 IMiMTCE, or approximately 46 percent of total US. p emissions. Other agricultural soil management practices, such as irrigation, tillage practices, or laying fallow the land, can ~I S O affect fluxes to Other Sources and from the soil. However, because there is much uncertainty about the direction and magnitude of the Methane is also Produced from several other effects of these other practices, only the emissions sources in the United States, including energy related from fertilizer use and field burning of agricultural combustion activities, wastewater treatment, indus lvnstes are included i n the U. S. inventory a[ this time, trial processes, and changes in land use. The sources included in the U. S. inventory are fuel combustion `Fossil Fuel Combustion and wastewater treatment, which accounted for approximately 4.6 and 0.9 MMTCE, respectivelp in 1995. These emissions represent about 3 percent of total U. S. methane emissions. Additional US. anthropogenic sources of methane  such as ammo  nia, coke, iron, steel production, and land use changes  are not included because little information on methane emissions from these sources is currently For converters installed to a v a i l a b l e . . promoted the formation of N?. As the number of catalytic converter equipped ;. chicles has risen in the U. S. motor vehicle fleet, so have emissions of $dl N, O is a product of the reaction that occurs between nitrogen and oxygen during fossil fuel combustion. Both mobile and stationary sources emit N, O, and the volume emitted varies according to the type of fuel, technology, or pollution control device used, as well as m$ intenance and operation practices.

Nitrous Oxide Emissions f r o m t h i s s o u r c e (DOEEIA, 1993b).

Nitrous oxide (N, O) is a chemically and radia In 1995, N, O emissions from mobiIe sources tively active greenhouse gas that is produced natu totaled 9.2 MMTCE (or 23 percent of total J$)

and water. While 50 emissions of are much lower were 3* 0 than CO, emissions, NP is approximately 310 times more powerful than C0, at trapping heat in the Adipic Acid Production atmosphere over a 100 year time horizon (IPCC The vast majority of all adipic acid produced in 1996). the United States is used to manufacture nylon 6,6. During the past two centuries, human activities N20 is also used to produce some low temperature have raised atmospheric concentrations of N, O by lubricants, and to add a "tangy" flavor to foods. approximately 8 percent (Figure 3 8, Table 3 4). rally from a \vide variety of biological Sources in soil emissions), and Bo emissions from stationary The main anthropogenic activities producing NQ are soil management and fertilizer use for agricul ture, fossil fuel combustion, adipic acid production, and nitric acid production (seeTnble 3 4 and Figure 3 8). While emissions from soil management and fertilizers remained relatively constant during 1990 93, they increased during 1994 95 because of intensified fertilizer applications to speed recovery of nutrients lost to the 1993 floods. N, O emissions from all other sources showed no significant changes. Table 3 4 Agricultural Soil ivlanagerneni and Fertilizer Use Fossil Fuel Consumption Adipic Acid Production Nitric Acid Production Agricultural Waste Burning 0.21 18.

0 12. 0 5 0 3 < <

TOTAL EMISSIONS . 0.47 ..

39.5 :

Greenhouse Gas Inventory  13 Figure 3 8 U. S. Sources of Nitrous Oxide Emissions in 1995 Adpic Acid Nitrfc Acid pcductjon Field Burning of a Agnkufturaf Wastes Fossil Consumption (31.4%) Management and Fertilizer Use (46%)

In 1995, U. S. adipic acid production generated 5.2 MMTCE of nitrous oxide, or 13 percent of total 1995, agricultural bl ng contributed approxi mately 0.01 MMTCE of N, O emissions to the atmosphere.

land use changes because of uncertainties in their effects on fluxes in IjO and trace gases, as .well as poorly quantified statistics on them. These changes include forest activity, reclamation of freshwater wetland areas, conversion of grasslands to pasture and cropland, and conversion of managed lands to grasslands. The U. S. inventory does not account for several Emissions from HFCs, PFCs and SF, Hydrofluorocarbons (HFCs) and eerfluorinated U. S. N20 emissions. By 1996, all adipic acid producdcompounds (PFCs) have been introduced as alterna tion plants in the United States are expected to have tives to the ozone depleting substances being phased N, O controls in place that will reduce emissions up out under the Montreal Protocoland Clean Air Act to 98 percent, compared to uncontrolled levels. (One Amendments of 1990. Because HFCs and PFCs are halfof the plants had these controls in place and not directly harmful to the stratospheric Ozone layer, operating in 1995.) they are not controlled by thaMonrrea1 Protocol. However, these compounds, along with sulfur  Nitric Acid Production hexafluoride (SF,), are powerful greenhouse gases. Nitric acid production is another industrial ' Therefore, they are considered under the United Source of N, O emissions. Used primarily to make' Nations' Framework Convention on Climate Change synthetic co& nercial fertil izer, this raw material is also a major component in the production of adipic acid and explosives. Virtually all of the nitric acid that is manufactured commercially in the United States is produced by the oxidation of ammonia, during which r\ TO is formed and emitted to the atmo sphere. In 1995, about 3.6 MMTCE of N20 were emitted from nitric acid production, accounting for 9 percent of total U. S. NQ emissions.

Other Sources of N, O Other N, O emitting activities include the burning of agricultural crop residues and changes in land use. In C?. FP%!!!!!

HFCs HFC 23 HFC 1 25 HFC 134a HFC 143a HFC 152a HFC 227 HFC 4310 PFCs CF4 C2Fs C4FlO c6F14 PFCs/ PFPEs'

s F6 .... .. MMT of Gas 0.02071 0.00426 0.00227 0.01 086 0.00004 0.00091 0.001 86 0.00051 .......

~0.00410 0.00250 0.00057 0.00001 < 0.00001 0.00102 0.001 29 ....... Atmospheric GWP ......... Lifetime (yrs) ... ..... Vrdue __ "TCE 20.92 264 11,700 33 2,800 15 1,300 48 3,800 2 140 37 2,900 17 1,300 7.93 50,000 6.500 10,000 0.200 2,600 7,000 3,200 7,400 7 3,200 23,900 8.40 'PFCIPFPEs are a pro4 for many diverse PFCs and perfluoropolyethers (PFPEs) which are beginning to be employed in solvent applications. GWP and lifetime values are based upon c6F1:.

14  US. Climate Action Report  // , / .?

Emissions of CFCs and Related Compounds ..

. .... Chlorofluorocarbons (CFCs) and other halogenated compounds were f this century. This family of human made compounds includes CFCs, ha1 tetrachloride, methyl bromide, and hydrochlorofluorocarbons (HCFCs). T variety of industrial applications, including foam production, refrigeration cleaning, sterilization, fire extinguishing, paints, coatings, other chemical miscellaneous uses (e. g., aerosols and propellants).

Because these compounds have been shown to deplete stratospheric to as ozone depleting substances (ODSs). In addition, they are importa they block infrared radiation that would otherwise escape into space (IP Recognizing the harmful effects of these compounds on the atmosph signed the MontrealProtocolon Substances 3 consumption of a number of them. As of Apr M United States furthered its commitment to phase out these substances by signing and ratifying th Copenhagen Amendments to the Montreal Protocol in 1992. Under these amendments, the U. S. committed to eliminating the production of halons by January 1, 1994, and CFCs by January 1, 1 The IPCC Guidelines do not include reporting instructions for emissions of ODSs because their use is being phased out under the Montreal Protocol. Nevertherless, because the United States believes that no inventory is complete without these emissions, estimates for emissions from several Class 1 and Class II ODSs are provided here: Compounds are classified according to their ozone depleting potential and must adhere to a strict set of phase out requirements under the Montreal Protocol.

Class I compounds are the primary ODSs; Class I I compounds include partially halogenated chlorine compounds (HCFCs), some of which were developed as interim replacements for CFCs. Because these HCFC compounds are only partially halogenated, their hydrogenkarbon bonds are more vulnerable to oxidation in the troposphere and, therefore, pose only about one tenth to one hundredth the threat to stratospheric ozone, compared to CFCs.

Also, the effects of these compounds on radiative forcing are not provided here. Although CFCs and related compounds have large direct global warming potentials, their indirect effects are believed to be negative and, therefore could significsntiy reduca tha magnitude of their direct effects (IPCC 1992). Given the uncertainties surrounding the net effect of these gases, they are reported here on a full molecular weight basis only. ........ Compound ~

".

Ch55 /Compounds CFC 11 CFC 12 CFC 113 CFC I 14 CFC I 15 Carbon Tetrachloride Methyl Chloroform Halon 1211 Halon I301 Chs5 // Compounds HCFC 22 HCFC 123 HCFC 124 HCFC 141 b HCFC 142b  Emissions " .

0.036 0.052 0.01 7 0.002 0.003 0.005 0.046 0.001 0.002 0.092 0.002 0.005 0.01 9 0.020 Greenhouse Gas Inventory  15 Emissions of Criteria *

Pollutants  Table 3 6 shows that fuel consumption accounts for the majority of emissions of these gases. In fact, motor vehicles that bum fossil fuels contributed In the United States, carbon monoxide (CO), approximately 81 percent of all U. S. CO emissions in nitrogen oxides (NCI), nonmethane volatile organic 1995. Motor vehicles also emit more than a third of compounds (NMVOCs), and sulfur dioxide (SQ) are total U. S. NOx and NMVOC emissions. Industrial commonly referred to as '( criteria pollutants." CO is processes  such as the manufacture of chemical and produced when carbon containing fuels are burned allied products, metals processing, and industrial incompletely. Oxides of nitrogen (NO and NC; 3 are uses of solvents  are also major sources of CO,

created by lightening, fires, fossil fuel combustion, , NOx, and NMVOCs.

and in the stratosphere from nitrous oxide. NMVOCs ~

 which include such compounds as propane, butane, and ethane  are emitted primarily from transporta tion and industrial pro cesses, as well as forest wildfires and nonindustrial consumption of organic . solvents. And SO, can result from the combustion of fossil fuels, industrial processing (particularly in the metals industry), waste incineration, and biomass burning (U. S. EPA 1996). 1995 Emissions of CO, NOx, NMVOCs, and SO .. (MillionMetricTonnes): . .

sources ...... . .. . .... .... "T ..... ._.: ....... ... E?. ox .... MUTCE  "_ . , .. .....

Fossil Fuel Combustion 70.95 . 18.75 8.22 Industrial Processes 5.15 0.71 4.13 Solvent Use ' < 0.01 < 0.01 5.80 Waste Disposal and Recycling 1.60 0.01 2.1 9 Other Combustion 5.86 0.21 0.41 TOTAL '. .... ..

.... 83.55 .; 19.? 3 20.74 ... ... i . ...

so2 1473 1.83 < 0.01 0.03 0.01 ...... ..... "

.......

16.60 .... .. ...

16  US. Climate Action Report "_

B O ? 3 3 Sources and Effects of Sulfur Dioxide ..

Emitted into theatmosphere through natural and human processes, SO2 affects the Earth's radiative budget through photochemical transformation into sulfate particles that (1) scatter sunlight back to space, thereby reducing the radiation reaching the Earth's surface; (2) possibly increase the number of cloud condensation nuclei, thereby potentially altering the physical characteristics of clouds; and (3) affect atmospheric chemical composition  e. g., atmospheric ozone  by providing surfaces for heterogeneous chemical processes. As a result of these activities, the effect of these SO2 emissions on radiative forcing is likely negative (IPCC 1996), although the distribution is not uniform.

SO2 is also a major contributor to the mix of urb3n air pollution, which can significantly increase acute and chronic respiratory diseases. Once SO2 is emitted, it is chemically transformed in the atmosphere and returns to the Earth as the primary source of acid rain. Because of these harmful effects, the United States has regulated SO2 emissions in the Clean Air Act of 1970 and its subsequent 1990 amendments.

Electric utilities are the largest source of SO2 emissions in the United. States, accounting for about 66 percent of total SO2 emissions in 1995. Coal combustion contribute3 approximately 96 percent of those emissions. SO2 emissionshave significantly decreased in recent years, as electric utilities have increasingly switched to lower sulfur coal and natural gas. The second largest source is fuel combustion for metal smelting and other industrial processes, which produced about 20 percent of 1995 SO2 emissions (U. S. EPNOAQPS). /

I "

I IPCC. 34. Clinrnte Change 1994: Radiative Forcing of Climate Change and an Evaluation of the IPCC IS92 Emission Scenarios; J. T. Houghton, L. G. Meira Filho, J. Bruce, Hoesung Lee, B. A. Callander, E. Haites, N. Harris, and K. Maskell, Eds.; Intergovernmental Panel on Climate Change: Cambridge; pp. 1 34.

IPCC. 1996. Climrie Change 1995: Tj2e Science of Clin~ ate Change; J. T. Houghton, L. G. hleira Filho, B. A. Callander, N. Harris, A. Kattenberg, and K. Maskell, Eds.; Cambridge University Press. Cambridge, U. K.

IPCC/ OECD/ IEA/ UNEP. 1995. IPCC Guidelines for Nariond Greenhorlse Gas Inventories, Vol. 3, Reference Manual; Intergovernmental Panel on Climate Change, Organization for Economic Co Operation and Development, Internatjonal Energy Agency, United Nations Environment Program:  Brecknell, UK; pp. Preface l Overview 7.

US. EPA. 1995. bwentory of US. Greenhouse GAS Emissions and Sinks: 1990 1994; Office of Policy, Planning and Evaluation, Washington, D. C.

U. S. EPA. 1996. National Air Pollutant Emission Trends, 1995, Office of Air Quality Planning and Standards, Washington, D. C.

U. S. EPA. 1997. draft of Inventory of U. S. REFERENCES United States Department of EnergyEnergy Information Administration (DOEEIA). 1993. Emissions of Greenhouse Gases in the United States: 1985  1990. U. S. DOE, Washington, D. C. DOE/ EIA 0573.

DOEEIA. 1996a. Emissions of Greenhouse Gases in the United States 1995; Energy Information Administration, U. S. Department of Energy, JJ'ashington, D. C. DOEEIA. 1996b. Annual Euergy Review 1995; Energy Information Administration, U. S. Department of Energy, Washington, D. C.

IPCC. 1992. Climate Change 1992: The Supplementary Reporr to the IPCC Scientific Assessmenf. University Press, Cambridge, England. Greenhouse GAS Emissions and Sinks: 199O i99$ Office of Policy, Planning and Evaluation, Washington, D. C.

United States Forest Service (USFS). 1990An Analysis of rhe Timber Sirmrion in the United States: 1989  2040: A Technical Document Supporting the 1989 USDA Forest Service RPA Assessment. Forest Service, United States Department of Agriculture. General Technical Report &\ I 199. Seki, M., Christ, R. 1995. African Regional Wrkshop on Greenhoirse G ~J En1ission Inventories and Emission Mitigation Oprions: Forestv, Land use Change and Agricrdturc Uh'EP.

Greenhause Gas Inventory  17 PUBLIC HEALTH EmCTS OF CLIMATE CHANGE: SYNTHESIS OF THE lPCC FINDINGS"

Jonathan A. Patz, MD, MPH Department of Envifo ental Health Sciences & Department of Molecular % cmbidogy and Immundgy Johns Hopkins School of Hygiene and Public Health Statement prepared for a Roundtable Discussion of SENATOR JCSEPW I. UEElERMAN United Scates. Senate, June 11,1996 Plaintiff 1 4 1 0 9 5 5 1 8 1 1 0 .6 1 0 9 6 . 02: 07FbI PO02 g 2 2 . .... . .... ..... .... ..*. . * Public Health  Effects Of Climate Change: Synthcsts Of The IPCC Findings Pak, J. A.

ABSTRACT Climatologists have identified upward trends in global temperatures and m w estimate a rise of 2. WC by the year 2100. Of major concern in the health community is that these changes can cause an increase in both direct and i n d k m health outcomes such as: 1) mortality and morbidit dated to heatwaves and increased urban air pollution; 2) re emergmce of serious vector borne in ty &om diseases: 3) spread of water borne diseases from hydrological extremes and elevated sen surfsce temperatures; 4) malnutrition from t h r e a t e n e d food supply; and 5) general public health infrastrucrural damage from weather disasters and sea level rise.

Temperatures above threshold levels andlor particular types of air masses can be directly hazardous to human health, musing mortality in vulnerable populations. Infectious agents which cycle throughcold blooded insect vectors to complete their development, however, tend to be sensitive to very subtle climate variations. In temperate &ions, climare change wouId affect vector borne diseases by altering the vectoT's range, reproductive and biting rates, as well as pathogen development rate within the vector host For example, the geographic mge of malaria is gmedly limited to the tropics and subtropics because the PIamroditium parasite requins an average temperature above 16" C to develop Freezing temperatures kill overwintering eggs of Aedes mgypzi, the mosquito canier of dengue and yellow fever, and warmer temperatures shorten dengue virus extrinsic incubation periods, potentially accelerating transmistdon rates.

Climate related increases ia sea surface temperature can lead to higher incidence of water borne cholera and shellfish pisoning, Marine phytoplankton blmm5 include red tides that cause diarrheal and paralytic diseases. Vibrio choler& has been found to be associated with marine zooplankton, and blooms from warmer sea surfacetempwatures could expand this important reservoir from which chdera epidemics may arise.

Human migration and damage to health infi ashuctures from the projected increase in climate variability and severity of storms could thMen human shelters and public health infrastructures and indirectly contribute to disease tratlstnission. Furtkmore, projected increases in extremes of the hydrologic cycle can impact diarrheal diseases; drought in developing countries compromises personal hygiene, while flooding in developed agricdtwal areas can increase exposure to Cryptosporidim. Human susceptibility to disease might be further compounded by regioN matnutritiondue to climate impacts on agriculm, and perhaps, by immunosuppression caused by in& flux of ultraviolet radiation due to stratospheric m e depletion. Elite& of stratospheric omne depletion may act synergistically with health outcomes of Climate change, though the chlorofluombon chemical destruction of strawspheric omne is, for the most part, a different anthropogenic process than is g r ~~h o ~~e warming (climate change).

Analyzing the dosts d climate change's influence on human diseases will require interdiscipIinW cooperation and must account for both disease burden and costs of adaptation and prevention, Internenlions can occur at varying points along disease camation and each level carries vatying costs. Generally, steps are more cost effective when occurring early in the course of disease progression; indeed, considering the irreversibk nature of some of the health hazards associated with clinak change, upa~ caa intervention strategies maybe particularly beneficial in this case. Inkmali~ nal d i w sweiliance, in wmbination with ecological and ciimablogical monitoring will afford more anticipatory measures ta optimize proactive preventive measures. Integral& assessments at multiple geographic levels and ~CTOSIS varying sc= ctms are necessary to better understand climatological and ecologiCat change as determinants of human health.

R 98% 2 4 1 0 9 5 5 1 8 1 1 0 6 1 0 9 6 02: 07PM PO03 #2 2 R 98% Table of Contents INTRODUCTION Nature of tire Probkem ANTICIPATED HEALTH IMPACT OF CLIMATE CHANGE Heat= reluted Morbidity and Morlaliiy Climate, Air Pollution Vuctar borne Diseases. lL& zlmh Dengue and Dengue Hmrrhagic Fever Other Vecm bormDkeases MaAm Ecology: Cholera & Toxic Algae Agriculture I Human Nutrition Sea Level Rise, Extreme Weather Events and Climate Vcviabiflty Stratospheric Ozone Depletion: Spaergistic Impacts on Hetiiih CUmate Obrenntions for Zhe U. S. Hsaf related Mortuk'tg  US. Vector borne Diseases  U. S. Waterborne Diseases  US. costs to t h U. S. POTENTIAL HEALTH IMPACTS IN THE UNITED STATES RECOMMENDATIONS integruted Apptoacher To Improvs The Asfessment Of Health Impacts Levels of Prevention: the Public Health Model CONCLUSION 3 4 1 0 9 5 5 1 8 1 1 06 10 96 02: 07PM PO04 #2 2 .. .. . .. . .. . . . .. . .. ,INTRODUCTION The first assessment report of the Intergovernmental Panel on Climate Change (IPCC) focused on natural and managed resources, such as forests, agriculture, coastal mnes and fisheries; initially there was little attention given to the public health effects of climate change. While it is clear that the. health af human populations depends on these sectors, only recently have public health scientists become concerned abuut the mare primary effects of greenhouse warming on human diseases. The debut of a chapter dedicated to human health in the Second Assessment Report of the IPCC ROW provides a platform on which to focus further efforts in this field.

The World Health Organization (WHO) has been integrally involved with the writing of the population health chapter uf IPCC. In several weeks the WHO will release its own major monograph, "Climate Change and Human Health, ' which expands upon the findings highlighted by tbe IPCC (WHO, in press).

Nature of the Problem According to the health chapter af the IPCC Second Assessment Report (" ichaet et al., 1gg6), the scale ofthe anticipated health impacts is that of whole cornmunitm orpop~~ Iations dm than at the individual level. Human health impacts would occur via pathways of varying directness and complexity, including distuhce of naturai and managed ecrrsystems. Research to this point mostly has been qualitative, with the exception of recent studies on heat mortality and mathematid modeling of infectious diseases. Qualitatively, however, the aggregate b d health implications  are of major concern and are presently receiving far more attention from the medical and public health communities, including agencies and imtitutions such as the Cenbers for D i m e Control and Prcvcntion, the Environmental Protection Agency,. the National Institutes of Health, the institute of Medicine and ?he National Academy of Science as examples.

Most of ihe impacts are expected to be adverse, though regionally some areas may benefit. Some J impacts would occur via relatively direct ways, such as from heatwaves and floods; others would occur via less direct pathways, changes in habitat that may define the distribution of dime carrying insects. Some impacts would be deferred in time and would QCCW on a largq &e than most other environmental health impacts with which we are familiar. If long t e r m clime change mues, indirect impads would probably predominate. These represent public health problems at a relatively new level of sde, being glow geographically and placing p p l a t i m rather than individuals at risk. Furthermore, as the health impacts likely would occur wef an extended time scale, it will be diffidt to discern them from natural variation, making & h e f i t s of early preventive measurn more difficult to identify.

ANTICIPATED HEALTH IMPACT OF CLIMATE CHANGE The main physical components anticipated from climate change are: 1) tempemhue elevation with concomitant precipitation changes; 2) = level rise (primarily from thennoexpansion of oceans); and 3) extreme weather events  rticularly in the hydrologic cycle, e. g., flaxis and droughts (Houghton et at., 19%). These c E n ges may lead to an increased frequency of heat waves and potentially hazardous air pollution episodes, reduced soil moisture, severe sbms and coastal flooding. Subsequent health effects may include an increase in: 1) heat related ri. r. odity 2. d morbidity; 2) vector borne diseases, e. g., carried by insects or small rodents; Sj water borne diseases both from f l d i n g and from altered marine ecology; 4) malnutrition from threatened food and water supply; and 5) general public health infrastructurd damage from weather disasters, sea level rise, and forced human migration (see figwe 1).

4 R 98% 4 1 0 9 5 5 1 8 1 1 0 6 1 0 9 6 02: 07PM PO05 #2 2 He& related Morbidity and Moriality , Although humans have a great capacity to adapt to adverse environmental conditions, them m limits to physiologic accommodation (Kilboumt, 1989). Weather conditions exceeding threshold temperatures and petsiating for several consecutive days can cause increased mentality in the population. In lwge urban areas, poor housing combined with the urban "heat islend" effect further women8 ccr~~ iitions. ' Hevated night time teinperatwe readings offering no relieffM '.

oppressive daytime heat  m the most significant meteoroiogical variable mtrihuting to heat related mortality; the greenhow effect is predtded to especially a. f€ ect these minimum tenqxranrres (Kalkstein & Smoyer, 1993). Higher latitudes are ex d to w m disproportionately more than tropical and subtropical zones.

According to the IPCC report (MeMichael et al., 1996), the frequency of extremely hot days in temperate climatea would approximately double far an increase of 2 3° C in the average summw temperature (CDC, 1989; C l m t e Change Impacts Review Group UK, 1W1). Extensive research has shown thal heatwaves cause excess deatha( Weihe, 1986; Kilbourne, 1992), many of which are due to i n c r e a s e d demand on the cardiovasculgg system required for physiologic cooling.

Death rates in temperate and subtropical zones are higher, however, in winter than in summer (Kilboume, 1992) and it is a reasonable expectation that milder winters in such countries would entail a reduction in cold related deaths and illnesses. Yet, summer related deaths appear to be more related to temperature extremes than are winter related deaths that may be m a a function of . indmr confinement with increased contact to infectious agents such as respiratory viruses; this expected reduction in winter mortality may not fully offset the heat related incteases (McMcW et  al., 199r5).

Mortality f r m extreme h t is increased by crmcomitanr conditions of low wind, high humidity and intense solar radiation (Klbourne, 1992). These meteordogid elements have ken treated synoptically or wholistidly as one approa& to evaluate the net effect of weather on human health. f i r example, recent studies in the US. have described "offensive" air masses which represent synoptic meteorological situations statistically associated with human mortality. TIris approach recognizes that humans principally res@ to the envelope of air that surrounds them (Kalkstein, 15 93}, It should also be m d that concurrent hot weather and air pollution have synergistic impacts on health (Katsouyanni et al., 1993).

Climate and Air Pollution climate change can indirectly alter urban air pollution by altering local weather patterns (Scott et ai., 1%), and atmospheric chemical reactions. l3qxsure to air pollutants has broad public health implications. Chronic expure to o m e bas been shown to exambate asthma and impair lung function in children and the elderly and chronic expure to fine particles is a came of excess deaths and morbidity (Dockery et aL, 1993; Pope et al., 1995). Over 1 billion people are exposed to excessive particulate levels and nearly 900 million are expDsed to unhealthy levels of sulfur dioxide {Scott et al., 1M).

Under the conditions of global warming, air pollution exposure may be exacerbated given cunent trends in urbanization, combined with increasing fossil fuel combustion, Warmer tempratlrres canbind with inc& ambient ultraviolet( UV) radiation could worsen air pollution, especially over urban areas. UV photodecompsition of nitrogen oxides (NOx) in the presence d volatile organic compounds (VOC) results in the secondary prduction of Voposphehc mme. Such increases in photochemical smog formation will likely cause health hazards in semi wid, suqny citics such as Los Angela and Mexico City (Scott et al., 1%). Adding to health hazards of this type of air pollution, concentrations of allergenic ajrborne pollen may change with vegetation$ response to a shifting climate regime and to the "fertilization" effect afforded by higher atmospheric CCQ levels.

R 98% 5 4 1 0 3 5 5 1 8 1 1 0 6 1 0 3 6 0 2 : 07PM PO06 #22 Vector borne Direures , Infectious diseascsare still the world's leading cause of fatalitiea killing over 17 million people annually (WHO, 1996). Vector borne diseases (primarily carried by i n s e c t M small mammal "vectors') and water borne diarrheal diseases represent a large proportion of these, For example, according to the WHO report, last year malaria alone killed 2.1. million and diarrheal diseases k i l l e d 3.1 million, most being children.

I t is well recognized that climate conditions directIy affect disease vector andlor parasite biology, as dmentrxl below. In addition, however, climate's indirect health impact OD, regional food supply with subsequent nutritional status and on forced human migration may substantially alter susceptibility to infections as well. It is also imperative to view climate change's e f k t s within the cuntext of other key determinants of disease, such as swioeconomic or cultural factors, to better evaluate population vulnerability.

Bacteria, viruses or parasites which cyde ttuough cold bWed insect vectors to complete their development are quite sensitive to subtle climauvariations (Dobson & Carper, 1993). Temperature determines vector infectivity by affecting ogen replication, maturation, and the period d infectivity (Longstreth & Wiseman, 1989). Epatfi evated temperature and humidly d80 intensify the biting behavior of most inseds. Table 18.3 from the fFCC repwt summarim widespread vector borne diseases and rankB their l k l i h d of being influenced by climate &w e .

Disease carried by small dents, whose populations strongly depend on their surrounding environment, also likely would respond to climate related ecological change. br example, the  pulmonaiy hantavirus epidemic in the southwest U S was felt to be due to an upsurge In rodent pulations related to climate and ecological conditions (Wenzel, 1994). Six years of drought, !% owed by cxtremely heavy spring rains in 1993, resulted in a 10 fold increase in the population of deer mice, which can carry hantavirus (Stme, 1993; Levins et at,, 1994).

Floods and hurricanes also significantly affect vector he diseases. More aquatic breeding sim for mosquitos translates into higher insect population densities. Moreover, destruction of shelters leaves human ppulations more likely to come into contact with infective mosquitoes. Simultaneously, Infect& humans exped to the elements beccmne a more readily wccessitae reservoir of dieease from which epidemics may be fueled by the mosquitoes which feed upon them. ,. _:

Two of the world's most widespread ~ector born~ dim are malaria and dengue fever. These are highlighted below as illustrative examples of h o w climate change can strongly influence disease transmission. Bear in mind, however, that other determinants of disease must be considered simultaneously to determine site specific poplation vulnerability to the altered risk potentid.

Malaria,  Malaria is the most prevalent vector borne disease globally, and causes 350 million new c ~s e s and 2 million deaths annually (Institute of Medicine, 1991). Control of malaria has been disappointing and the number of cases annually is increasing. Malaria generally occurs throughout the tropics and subtropics primarily because the malaria parasite cannot develap inside its mosquito h a t at temperatuns below 16° C (GilIes, 1993).

Temperature and humidity are among the most important determinants of disease transmission and the exbinsic incubation period of the parasite shortens dmnatidy at ternprztwes krween 20" 27° C (Ncden et al., 1995; Gilles, 1993). The extrinsic incubation period (EIP) is defined as the number of days between the vector's ingestion of an infected Mood meal and the point that i t becomes capzble oftransmi# ing infection, Climatic factors that increase the inoculation rate of Plamrodiwn pathogens, as well as Che breeding activity of Anopheles mosquitoes, are considered the most important cause of epidemic outbreaks of malaria in nm endemic areas (Gilles, 1993).

R 98% 6 4 1 0 9 5 5 1 8 1 1 06 10 96 02: 07PM PO07 #22 Unseasonably bot w e e r has been found to increase malaria transmission, for example, in , Pakistan (Bouma e€ al., 1994), and bas been associated with malaria occurring at higher altitudes in Rwanda (Loevinsohn, 1994) Under climate change scenarias (Martcsns et al., 1995; Matsu& a & Kai, 1993, risk of malaria epidemics would rise subtantially in both t r o p i c a l and temperate regions. More than one million additional fatalities per year is estimated to be attributed to dimrite change by the middle of the next century, according to a model developed by Martens et al., which is cited in the lPCC report (Martens et al., 1994).

Change in disease di6tribUtiOn itself may be significant, let done inCreased mdaria cases. F; or example, large u r h highland populations in the tropics (ego, Nairobi and Harare) that are ~Q K endemic for malaria are also immunologically naive to the disease; fhese populations are at far greater risk of serious illness than are populations where malaria currently occurs Ipatr; et d., 19%).

Dengue andDengcre Hemonha ic P e w .  Over the past 15 years, epidemics of dengue, or breakbone fever'  an extreme f y painful ff u like. illness  have increased in both number and severity, especially in tmpid urban centers. Dengue hemcxrhagic fever (DHF), a more sex iow variant of dengue, usually associated with second infections of dengue virus, now ranks as one of the leading causes for hospitalization and mortality of children in Southeast Asia (Institute af Medicine, lm), and i s on the risein the Americas (Gubles & Trent, 1994; PAHO, 19%). Urbanization, inadequate mosquito contrd, aLsence of water systems, and international travel m migration m major factors leading to the reemergence of dengue (PAHO, 1994; Gubler & Clark, 1995). Climate conditions, however, contribute to epidemic Spread and geogmphic distribution  (Macdonald, 1956; Reiter, 1988).

The range of the primary mosquito vector, Ae& s mgypri, (which also carries yellow fever) is limited because freezing temperam kill bofh larvae and adults. Warming trends, therefore, may shift vector and disease distribution to higher latitudes and altitudes. In Mexico in 1986, the must important predictor of local dengue transmission was found to be the median tempe e during the rainy season (Koopman, et al., 199l), and dengue was observed in Mexico at w1 unprecedented altitude of 1,700 meters during an unseasonably warm summer in 1988 (Henera Basto et al., 1992).

Temperature also affects the transmission dynamics of dengue. Warmer temperatures reduce mosquito larval size (Rueda et al., 1990). Smaller hatching adults must feed more frequently to develop EUI egg batch (Macdondd, 29%; Scott et al., 1993), boosting the incidence Of multiple reeding within each egg laying cycle (Macdonald, 1956; Pant Lk Yasuno, 1973). Additionally, viral development inside th. e r n a q u i t o shortens with higher ternpratures (Watts et al., 1987; &iter, 1sK18), increasing the pmpOmm of mosquitoes that become infectious at a given time (Fock3 et d., 1995). In summary, higher temperature leadrr to more infectious mosquitoes that bite more frequently.

Ohher Vecmr barn Dkeares.  Onchccerciasis, or Viver blindness", is a prevalent form of blindness caused by a helminth (or worm) infection, Canid by blackflies, it is primarily found in West Africa and, to a lesser extent, in Latin America. Climate plays an important role in the Occurrence of onchocerciasis since the vector requires fast flowing water for successful. reproduction, and the adult vector can be spread by wind (WHO, 1935). A recent st~ dy found khp~ if temperature and precipik~",. chzqg LTW pi+ hrs of Mest Africa as ?r& ict& by some GCMs, blacMly populations may increase by as much as 25% at their current breeding s i b (Nils, 1995). Pokntial abmdonment of agricultural land in river valleys could add to regional food production problems (patz et al., 1996).

R 98% 7 4 1 0 9 5 5 1 8 1 1 @6 1 0 9 6 02: 07PM PO08 #22 African trypanosomiasis, or incuable and usUatIy fatal nslceping sichess" is canied by tsetse , flies, whose distribution depends on vegetation cover. Researchers in s~~ bsahamn Africa have correIated vegetation type to the population densitics of tsetseflies using s a t e l l i t e images to predict a large extension of regions at risk for this disease, assuming a 3° C temperatwe rise in mean monthly temperature (Rogers &t Randolph, 1991 & 1993).

Tick borne diseases are also eeasitive to climatic conditions but favor cooler temperatures. In Africa, Rogers and Randolph found mean monthly maximum temperature to be the shongest predictor of tick occumnce at the margins of endemic zones (Rogers Packer, 1993). OnIy2" C determined the difference between arm where tick$ are present or absent in southeastern Africa. In the southern US, Rocky Mountain Spotted Fever may decline due to ticks' intolerance of high temperanves and diminished humidity (Haile, 1989).

Murine Ecology: Cholera & Toxic A l p Over the past century, average sea surface temperature has increased approximately 0.7T (Haughton et al., 1992), and marine growth of dgae has been observed to respond to localized temperature increases in nutrient replete waters (from fertilizer runoff and sewerage release). warm water favors the growth of dinoflagellates and cyanobacteria (Valiela, 1984), that include rnw toxic organisms such aa red tides, which cause paralytic shell fish poisming, diarrheic sheU fish poimning. and amnesiac shell fish poisoning. Thw, climate induced changes in the production of both aquatic pathogens and biotoxins may jeopardize s d d safety for humans, sea m m &, seabirds, and fin fish (McMichael et al., 1996).

Zooplankton, which feed on algae, can m e as reservoirs for VibriochoZerae and other enteric pathogens, particularly gram negative mis (Epstdo, 1995). Latge coastal blwms may have conaibuted to the recent mulriepicentered choIera epidemic in Latin America. Quexmt forms of V. cb2era. e have been found to persist wittxini algae that a n revert to a culturslble (and likely infectiuus) state when nutrients, pH, and temperature permit (Huq et al., 1990). With warmer sea s u f a c e temperatures, cmstal algal blooms may therefore p n t i a t e cholera proliferation and transmission.

Agriculhue 1 Human Nutrition Climate change could adversely affect agriculture both by long term changes, such as r e d u c i n g soil moisture though evapotranspiration, and more immediately, by extreme weather events such as droughts, flooding (and erosion) and tropical storms (Meams, 1993). Sealevel rise couldafkct fd production thrwgh the combhation of inundation and i n c r e a s e d salinity of coastal farmlands (Haines & Pany, 1993). "C q fertilization," on the other hand, enhances photosynthesis and may initially benefitplants (Tegart et al., 1%). Increases in the intensity of rainfall in some regions wouId exacerbate soil erosion. The net global impact of these climate relatedchanges upon food production is highly uncertain (Reilly, 1994). While productivity in some regions may increase initially, longer term adaptations to sustained climate change may be less likely because of the limitations of plant phy8iology (Woodward, 19B7), and water availability.

According to the IFCC report, cljrnak change could also affect agriculture by long term changes in agmmysterns and by altered patterns of plant di and pest infestations (IvIcMichael et& 19%). C.@ fertilization would affect differently the two major metabolic categories of plants: the C3 plants (e. g., wheat, soya beans, rice, and p o t ~t c m )~ which worlr! I Y ~~X K ! psiE; tz! y, and ~2 C4 plants (e g., millet, sorghum, md ~iizc), mb~ ch tvauld lx UiLaff~ ted. Such infiuences on ttK climatically optimal mix of crop s p e c i e s would disturb patterns of saditional agiculture in some regions (McMichad et al., 19%). Controlling for CQ fertilization, a study involving 30 nations nevertheless estimated that 40  300 million additional peop le worldwide could be at risk from hunger due to climate change (Parry & Rosenzweig, 1993).

R 98% 8 4 1 0 9 5 5 1 8 1 1 0 6 1 0 9 6 02: 07PM PO09 .# 22 Sea Level Rise, Extreme Weather Event: and Climate YarsabiUty Sea Level Rise.  According to the IPCC rem, much of coastal B a n g l W and of Egypt$ heavily populated Nile Delta would lx flooded. For example, a sca level rise of one meter would destroy IS% and 20% of agridhlre in Egypt arxl Bangladesh respectivsly (Tegart et al., 1990). Some low lying, small island stam such as the Maldives and Vanuatu would be at risk of mal immersion and many other low lying coastal regions (for example, eastern England, parts of Indonesia, Louisianna, and parts of the northeast coast d Latin America) would be wlnerable. The displacement of inundated communities  prtic~ 1Iar1 thaw with limited economic, t e c h n i c a l , and social T~ SOUK'RS  would grcatIy incttase the risks o Y various infectious, psychological, and other adverse h d t h consequences (McMichA et al., 1996). 3

Other health effects of sea level rise include the disruption of stormwater drainage and sewage disposai, compromised sanitation and displacement of coastal dwdlen. Saline intrusion ofcoastal aquifers a u l d diminish fresh water supply and coastat farmland in addition to frank inundation. In many plares, industrial and agricultural depletiwof groundwater are already causing land subsidence, thus decreasing the threshold for impiszt. Some changes in the distribution of infectious disease vectors could occur (e+., Anopheles sundajcus, a salt water vector of malaria) (McMichael and et al., 1996),

Extreme W e a k Events,  More frequent extreme weather events are predicted to accompany global warming, due in part to increases in convective activity (Whetton et al., 193). More intense rainfall events accompanying global warming (fcazi et al., 1995), would be expected to increase tbe  occurrence of floods, and warmer sea sutface temperature$ can be expected to strengthen tropical cyclones (Houghton, Meira Filho et at,, 19%). Severe storms can caw direct physical hann to humans as well as'disrupt public health infmnucture, cawing contamination of water systems. Meanwkile, heavy storms create breeding sites for insects or favorable conditions for rodents that carry diseases. Destruction uf shelters leavehuman populations more exposed to infectious vecton, increasing the potential for epidemics.

Climatic effects on the distribution and quality of surface water, inchding increases in flaxling andlor water shortages, can impede personal hygiene and impair locaf. sewerage. Subsequent risks of dimheal (including cholera) and dysentery epidemics, parhcularly in developing wunaies would be expected to ensue (McMichael et al,, 1996). Diarrheal diseases can be caused by a large variety of bacteria (e. g., Salmonella, Shigella and Campylobacter), viruses (e. g., Rotavim), and protozoa (e. g., Giardia lamblia, amoebas, and Cryptosporidium). In addition, expected intensification of heavy rainfall even& could lead to more rapid leaching from hazardous waste landfills which are not watertight (Scott et d,, 19%). Toxic contamination of groundwater or swface drinking water would then pose a local health threat,

Human migration away from coastal, rural or other economically or physically vuinerabte k~ xti0n~ j could be anricipated. Already, droughts have fared mass migrations in West Africa and other parts of the world, compounding upward trends in urbanization (Scott et al., 19%). Also, many infectious disease endemic regions throughout the tropics and subtropics have been identifified being vulnerable to an increase in extreme weather events (Patz & Balbus, 1996). The potentid risk of epidemics could increase in urt3an settings as refugees anive from disease eridemic areas (Leaf, 1989; Hainw & FUC~ B, 1991). Already, current h n d s in urbanization incmx the p ~e ~f i d for disease epidemics such as cholera and dengue fever.

C I W e Variability.  Same of the anticipared health impacts associated with extreme climate variability are already within the range of arrent human experience. Many disease outbreaks have lzeen asscw= iated with the erratic wearher conditions driven by El Nido Southem Oscillation (ENSO) events. ENSO is a climate phenomenon that is second only to seasod cycles in i t s i m p & on regional climate variability (Nicblls, I%), and OCCUT on average every four years (Kifadis &

9 R= 98% C 1 0 9 5 5 1 8 1 1 06 10 95 0 2 :0 7 P f *l P O 1 0 #22 Dias, 1989). Anomalous fluctuations in precipitation, even to the extent of flaxIs or droughts, , known to result from climate variations ifluenoeri by ENS0 events.

Exbeme heavy Istinfalls havebeen c o r r t l a t e d with outbreaks of Munay Vally encephalitis and Ross River virus in Australia, eastern equine encephalitis in the US (Nicholls, 1993), West Nile k v e r in southern Africa (Glantz et al., 1991), cyclical malaria epidemics in Argentina (Macdonald, 1941), and Wstan (Zulueta, lW), Such climate related outbreaks have closely cumpod to ENSO cycles, which are now thought to be the driving force behind these geographical2y speuf1c extreme climaticconditions (Nicholls, 1991; Bquma et al., 1994). Maria can also be associated with droughts linked to ENS0 phenomenon when rivets pool  in Sri Lanka (Bouma et d., 1994). The devastating drought in countries of the Indian Ocean region in the past several years has been attributed to a persistent El Nifio as well (Glantz et al., 1992).

Sbatorpheric Orsns Depletion: Synergistic Im acts on Health Some consider stratospheric ozone depletion (Molina 8pRowlmd, 1974), accompanied by increases in ambient biologically destructive ulmviolet B radiation (UV B) (Ken & McElroy, 1993), alongside climate change, though it arises from a different anthropogenic process than does. the greenhouse effect. Partial justification stems from the fact that chlorofluorocwbns (CFCs), other halocarbons and methyl bromide are themselves pdent greenhow gases. Mormvw, the h a t trapping effect of greenhouse gases in the atmosphere results in reduced amounts of heat reaching t h e stratosphere; suhstsquent increases in ice crystal formation in the uppr stratasphere serves catalyst for Further destruction of the m e layer.

The d i r e c t health impacts from increases in UV B include: 1) skin cancer; 2) cataract and dhw ocular diseases: and 3) immunosuppression. Indirect effects to health may occur primarily tbugh UV mediated crop damage and by photochemical formation of tropospheric ozone (at the ground level as opposed to in the stratosphere). alluded to within the previous section on air pollution. Immunauppressim cwld exacerbate several of the health outcomes from geedm warming, especially infectious disease epidemics,

Regarding cancer, it is estimated that for a sustained 10% decline in the stratospheric ozone layer, non melanoma skin cancer cases could rise by 26%, or300,000 globally per year; mclanoma could increase by 2096, or 4,500 more cases mually (UNEP, 1Srgl). UV B radiation has also been associated with ocular cataract formation (Taylor, 1990); cataracts m u n t for half of all blindness in the world. A 10% sustained loss of stratospheric ozone would result in nearly 1.75 million extra cataractsannually (UNEP, 1991).

UV induced immunosuppression may exacerbate the effect of climate change on infectious diseases, particularly diseases of the skin such as onchocerciasis and dermatophytosis (fungal infections), and diseases where the skin is a portat of entry as in leishmaniasis (Giannini, 1990). UV light has been shown to cause immunosuppmsion in both animal and human studies (Jeevan 62 Kripke, 1990; Larcom et al., 19%); B a w d , 1991; UNEP, 1591; Cooper et d., 1992; IARC, 1992; Kripke, 1m; Cestari et al., 1! 295). UV B impairs antigen p m s i n g and presentation by Langerhan cells in the skin (Wolff & Sting, 1983; Cruz & Betgstresser, 1988; Morison, 1989), as well as altering lymphokine pfcductian, which reduces T hlperlT supprwor cell ratios at the systemic level (Noonan et al., 1981; DeFabo & Nmm, 1983; Hersey et a]., 1983; Kripke & Morison, 1986; Daynes, 1990). In shoh, i& UV€ 3 expasure may augment ihe potential fw disease emergence and dissemination by !owering human L r n 1 ~ defer. sB, :... .. .>

POTENTIAL HEALTH IMPACTS IN THE UNITED STATES '

While most of the health effects described above apply throughout many parts of the world, a few are particularly relevant dommticaUy, Climate change has been implicated in the continental US. and clc" examination of resultant health effects should follow.

10 4 1 0 9 5 5 1 8 1 1 R 98% 0 6 1 0 9 6 02: 07P? d P o l l #2 2 Health and Climate Change , CIimnie obssrvdwnr for the U. S. Climatic data for the U. S. reveal changes and variations that may be significant to human morbidity and mortality. Since the turn dthe century average daily temperature6 in the contiguous U. S. have increased by approximately 0.4" C, with most of t h i s i n c r e a s e occurring during the past 30 years (Karl et at., 199%). Recent studies have shown that the hydrologic cycle in the U. S. is changing as indicated by increases in cloud cover (Karl & Steurer, 1990) and precipitaticm (Gmisrnan & Easterling, 1994) and decreases in pan evapmdion (Petenson, 1995). Extremes in U. S. precipitation have been changing with increases in heavy precipitation events and ~~e s in lighter precipitatian events (Karl et al., 199%; E M et al., 1996). Using data back to 1910, Kixl et al. found that the most recent 15 y m had the highest values of Greenhouse Climate Response Index (GCRI) as well as Climate Extremes Index (Cn). It is becoming increasingly apparent that measurable changes in climate rrends are occurring in the U. S.

Heat related Mottuliiy  US. Temperate regions, such as the US, are o warm disproportionately more than tropical and subtropical zona @FCC, 1990). of c o n m t meteorological and mortality data in cities in the USA, Canada, the Netherlands, China, and the Middle East provide wnflmatory evidence that overall death rates rise during heat wave8 (Kalkstein & Smoyer, 1991; Kunst el id., 1W), particularly when the temperature rises above the I d population's threshold value.

Using data from Philadelphia for the years 1973 through 1988, Samet et al,, found a rdatimship  between temperature and humidity and daily mortality counts through regression rncdels (Samet et al.+ 19%). Long term trend and increasing variability both may be incmpomd into models. The tcmm relationship between temperature and mortality, was also found to have differing time lags for hotter and colder regions of the U. S.; and the magnitude of the health risk is age dependent.

In the IPCC report, the population of Atlanta wax given as an example of expected change in heat related mortality (McMichael et d., 1996). Presently, Atlanta experiences an average of78 k t  related deaths each summer. Under the climate projections of the GmL 1989 (transient) climate change GCM model, and assuming no change in population size or age rofile, this number would increase to 191 in the year 2020, and to 293 in the year 2050. With popu P ation acclimatization, the annual total excess mortality is 96 and 147 respectively. Under the T "R (transient) model m, the cwresponding four projectiohs of heat related mortality are 20 40? 6 higher than for the aFDL model run: 247 and 436 deaths (unacclimatized, 2020 and 2 0 5 0 ) and 124 and 218 deaths (acclimatized, 2020 and 2050). These and other results for selected North American cities indicate that the annual number of heat nlated deaths would approximately double by 2020 and would increase several fold by 2050.

Vector borne dioeaoer  U. S. Mosquito borne diseases,  Currently, dengue viruses are being transmitted in the npics between 300 north and 200 south latitude, (Trent et al., 1983) sinm frosts or mtaiXKd cold wealher kills a d u l t mosquitoes and overwintering eggg and larvae (Chandler, 1945; Shope, 1991). hem averages 10, OOO dengue fever cases annually, and dengue now occu~; s in nearly all Caribkn nations and Mexico, and periodically has been endemic inTexas in the past two d d e s . h e to the climate sensitivity of dengue a dp,. criM ir, &t& i a b l e , this disPae ma;. f ~h r ~hka *" ti: southern U. S. with climate change. Endemic malaria also cxmsionally arises in the U. S. and has recently been reported in Texas, New Y ork and New Jersey during unseasonably hot summers.

Of reported encephalitis cases in the US., most are mquito borne and, in order of prevalence in the U. S,, include: Saint Louis and Lacrosse encephalitis, and western, e a s t e r n , and Venezuelan 11 R= 98% 4 1 0 9 5 5 1 8 1 1 0 6 1 0 9 6 02: 07Pb! PO12 #2 2 equine encephalomyelitis (Shop, 1980). Clinical features range from headache to frank , m~ e@ ditis, with the elderiy at highest risk for mortality. Though mosquito longevity diminishes as pmpratures rise, viral transmission rates (similar to dengue) rise sharply at higher temperatures '

(see figure 2) (Hardy, 1988; Reisin et al,, 1993). From field studies in Callfonnia, (Reeves et d., 1994) researchers predict that a3 5'C temperature increase will caw a significant northern shift in both western equine and Saint Louis encephalitis outbreaks, with disappearance of western equine in southern endemic regions.

Human outbreaks of Saint io& s encephalitis are highly ux" dai& d With severalday periods when temperature exceeds 85OF( 30" C) (Monath & Tsai, 19$ 7), as was the case during the 1984 California epidemic thal followed a period of extremely high temperatures. Computer analysis of monthly climate data has demonstrated that excessive rainfall in January and February, in combination with drought in July, most often precedes outbreaks (Bowen & Francy, 1980). Such a pattern of warm, wet winters followed by hot, dry summers resembles the GCM projections for climate change over much of the U. S. (Schneider, 1990; Houghton, Meita Filho et al., 1996).

Tick borne diseuses.  Ticks transmit Lyme disease, the most commonvector bme disease in the U. S.. with more than 10, OOO cam in 1994, along with Rwky Mountain Spotted Fever, and EMidhiosis, which is rapidly emerging disease. Involved tick and mammal hwt ppulatians are influenced by land uselland cover, soil type, elevation, and the timing, duration, and rate of change of temperature and moisture regimes (Glass et al. 1994; Mount et al., 1! 393). The relationships between vector life stage pameters and climatic conditions havebeen verified experimentally in both field aod laboratory studies (Mount et al. 1993, Ooddard 1992). Climate change, therefore,  could be expted to alter the diatxibution of these diseases.

Waterborne Diseases  US. Cryptosporidiosis causes severe diarrhea in children and can be fatal to immuncmmpromised individuals and i s the most prevalent wakrbrne disease in the U. S. (Mwe et al., 1994). The disease is a zoonosis associated with dairy farms, domestic stock and water associated contamination. Natural events (eg. floods, storms, heavy rainfall, snow melt, and swollen fivers) wash material of fecal origin, primarily fm. agricultud non point sources into potable water. The Milwaukee outbreak in 1993 resulted in 4U3, ooO reported cases and coincided with unusually heavy spring rains and runoff from melting snow (WcKemie et al., 1994). The five best documented waterborne outbreaks of nyptosporidiosis in the U. S. were caused by bath cmtantinatim of water mums relared to aberrant weather and operational deficiencies ofthe water treatment facilities (Lisle &Rose, l! XB).

Factors enhancing waterbane Cryptosporidiosis will depend on hydrological responses to climate change snd degree of flooding in water catchment areas. Land use pattern determine agricultw contamination sow= and must therefore be considered. Watekbm diseases also will k. affected by salinity change from sea lev4 rise. In freshwater, the q s t dieoff rate is relatively hi& but saline water extends oocyst viability of this protozoan (Lisle & Rose, 1995). important implications for coastal recreational waters contaminated with sewage and runoff material containing Cryptosporidirun oocysts and concomitantly experiencing salinity changes secondary to sea level rise. 4 Cholera and red tides, as previously described, re sensitive to changes in marine ecology related io ciimate change, For example, one species of toxic algae previously mnfined to the G d f of Mexico, G'ymnaditu'um breve, extended northward in 1987 after a "parcel of warm gulf stream water" reached fu up the East Coast resulting in human neurologic shellfish poisonings and substantial fishkills (Tester, 1991). Cholera m u m in the Gulf of Mexico and human cases, which dready cccur in the U. S., may increase as sea temperatures w m .

12 X= 98% 4 1 0 9 5 5 1 8 1 1 0 6 1 0 9 6 0 2 :0 7 P M P O 1 3 #22 Cogts to the US.

a ~llness associated with climate change, whether it resultsin acute or chronic morbidity effects or in mortality, irnpoaes multiple costs to society: fox treatment (incIuding medical care, drugs, and hospitalization); lost work days and lowered productivity: and reduced quality of life. Farmany climaterelated illnesses, costs may also be incurred to prevent the spread of illness and reduce health impacts and associated costs. Such prevention programs include va: tw control actjvitieg, such a eliminating breeding pIaces or applying insecticides to animals or houses. Prevention can also take the form of widespread immunization or monitoring and watch warning systems Varying levels of mts will parallel the multipk points of intervention along the continuum of disease devcloprnent. In general, "an ounce of prevention is worth a pound of cure," since end stage trcatment options are nearly always more costly than proactive measurn.

Unintended costs of control measures must be considered, as well. For example, the adverse effects on public health and the environment resulting fram gene& pesticide use are estimated to CQSt between $100 billion and $200 billion arrsually worldwide (Pimend, 1990). Pesticides not only involve direct human toxic effects, but a l s u t ~y lead to insect resistance and reduction in natural predatory organisms. Mosquito resistance has been "extremely costly'' with regards to malaria control (Pant, 1987), and more than 50 species have developed resistance to i n s e c t i c i d e since 1947 (Brown, 1983). Risks to American military personnel overseas and to the tourist industry impose additional cos6 on the US.; 230, OOO cases of malaria were diagnosed in Vietnam veterans (Institute of Medicine. 1992).

RECOMMENDATIONS Integrated Approaches to Impruve the 'Arsssrment of Health hpacts Most human diseases that stem from hazardous environmental expoSUres are multifacrorid. Many of the primary determinants of human healtki (a d q u a food, clean water and secure shelter) are related to &e outcomes of sectors such as agriculture, water resources and fisheries. In populations suffering malnutrition problems, the effect of climate change on agricultural production may have a greater adverse effect on human health than any given disease. Therefore, it is important to integrate these relevant systems into the human health assessment.

One should also realize that it may not be possible to make firm predictions of climate related alterations in disease incidence for two main reasons, First, at a global level, the anticipated climate changes are beyond the range of recorded observations, and therefore, we have no direct evidence of human disease under these new conditions (McMicM, 19%) (though the site specific studies referenced throughout this ppet clearly show disease sensitivity to climate conditions). Second, we have a long way to go in our understanding the dynamics between climate, ecological change, and human health, which reduces our confidence in extrapolating from historical observatians, For these reasons, mathematicat mcdels can be useful where empirical observations are unavailabie. A number of integrated models are cumntly under development for such diseases as dengue and malaria (Fmks et al., 1993; Jetten 8c Takken, 1994; Martens et al., 1994).

For specific health assessments at the local level, geogra hically organized data is h o m i n g increasingly more useful in environmental exposure stu (E 'es. Examples of &ul analytical toois include: 1) geographic information systems (GIS) to organize gm gaphimlly~ disex, climate and demographic data; and2) remote *! k. se, nSng txhnology Wpoyidzs tduabli: data on land use patterns, habitat characteristics, and marine ecosystems (Glass et al., 1993). In m n t studies, GIS and remote sensing were used to identify weas receptive to dengue fever a d Lyme disease in the U. S., schistosomiasis in Egypt and the Philippines, and malaria in temperate rice growing regions (Glass et al., 1993; Washino & Wood, 1994).

R 98% 13 4 1 0 9 5 5 1 8 1 1 0 6 1 0 9 6 02: 07PM PO14 #22 An essential ste in recognizing and thereby preventing adverse health outoomes i s enhanced ,surveillance amfresponse. Early detectim ~1 1 not only provide an early warning fm possibly more pervasive changes in d i m behavior and allow for intervention, but will also enrich our knowledge of dimate related diseases and facilitate ?he creation of better predictive models,

In summary, the msesmexlt of the human'hedth risk posed by global climate change thus presents a new challenge to public health professionals. A framework for ecologically based human health risk assessment will need to be developed, since conventional dose response risk assessments may not apply to climate change health research. Studies should include historical analysis of climate and geographical discase data in cambination with simulation studies utilizing inregrated mathematical models.

k v s k of Prevention: the Public Henlth Model In addition to mrnmending further research, monitoring and education in addressing this long term health threat, we must begin to consider implementation of preventive options. Conventid preventive strategies in public health are classifie& s either primary, secondary, or tertiary in relation to the point along the causal pathway to disea~ a Primary prevention refers to avoidance or removal of a hazardous expure or otecting individuals SO that exposure to the hazard is of no consequence. Examples could inch r e venting of noxious fumes in an occupational setting a administering childhad vaccinations, rwpectively. Swxlndary prevention, somewhat '

'downstream" in the disease pathway, involves early detection (or screening) of an altered human physiologic state and subsequent intervention which averts full progression to disease, e. g., a mammogram for breast cancer screening. This also appliea to population wide screening for the  first "index case" of a disease which would dert health officials to bolster preventive rneasm to avoid subsequent cases, Finally, tertiary pevention, which in practical 'terms is trearment rather than prevention, attempts to minimize the advetse effccts of the already present disease. The further "upstream" an intervention can be impl'emented, generally, the greaterthe potential health benefit to the largest number of individuals. Likewise, the further upstream the pvention, the lower the per case cost.

Preventive measures should neither exwrbate the primary hazardous exposure, nor should they introduce new hazards themselves. In esserx= e, the "cure" must not be wow than tk "disease". Some options to protect populations are energy intensive, e. g., air conditioning, that will worsen greenhouse warming via increasing demand for energy unless alternative energy 80urces are developed. Vector control i s another response wit5 potentially h d u l side effecb as mentioned above. In essence, we must avoid solving om environmental health problem by compounding another.

Finally, policies to address climate change will be expected to have short and long tern benefits, and both must be considered in planning optimal preventive strategiw Health gains realized through the reduction in air pollution stemming from greedmuse gas reduction, for example, could substantial. Such short term gains must weigh into any policy decision, considering the inherent uncertainties of predicting long term hazardous expasures due to climate change. As with most of the health outcomes described abve, impacts from climate change should not be viewed in isolation fmm other determinants of health. This case of air pollutiw reduction "companying p s i ble climate change policy clearly illustrates the need to integrate this issue with o t h e r environmental health problems  in this case, air pollution and climate change, rpYicy go hmd irr L n m A CON@ LU$ ION In the history of public health and medicine, our specialized appmh to research (and prevention) has to this point been quite mccewfd in identifying single etiologic agents, including micrwrganisme, chemical toxins, and sjxcific harmful human behaviors. The Mth effects R 98% 14 4.109551811 0 6 1 0 9 6 02: 07PM PO15 #2 2 In dealing with these 6ompIex% sUes, we will be faced with making policy decisions, within a setting of inevitable uncertainty. Furthermore, efforts to duce the uncertainty of health risk assessment of climate change will require improved disease surveiUance and concerted efforts among scientists to achieve fully integrated assessments. The large inertia of the dimate system, requires adaptive options to be p c t i v c to reduce potentially large disease burdens.

Considering the magnitude and long term nature of the tial pblic health impacts from climate change, a rational approach would stress continued stu 8""" y and monitoring, accornahting a range of possible health outcomes. Similariy, preventive policies should emphasize measures that are appropriate for current conditions and build capacity to respond to both expected and unexpected threats to human health. Interdisciplinary links fw promoting an integrated assessment must be advocated to reduce these uncertainties. Yet, fora public healthchallenge as complex and potentially l a r g e (and possibly ineversible) as globat climate change, discussion must not only occur between health pfessiaals and scientists from diverse fields, but must extend include policy makers at all levels of the assessment. In an area with much uncertainty, such cooperatian will ultimately enhance the risk communication nece~~ ary for making informed decisions affecting the health of the public.

ACKNOWLEDGMENTS Special thanks to the primary reveiwers for this pap. Professor Anthony J. McMichael, Departmat d Epidemiology and Population Sciences, London School of Hygiene and Tropical Medicine, and Professor Jonathan Samet, Chairman, D e m e n t of Epidemiology, Jdhns Hopkins Schod of Hygiene and Public HeaIth.

M a l funding supprt for some ofthe healWctimate assessments cited in this paper has been provided by the Climate Policy and Assessment Division of the US EPA, Cooperative Agrement # CR823 143010. For valuable comments I thank Professor Andrew b i n e s , University College London Medid School and Dr. Rudi Sloaff, World Health Organization.

R 96% 15 $109551611 0 6 1 0 9 6 02: 0? PM PO16 #2 2 PAGE 82 Palr 16 4109551811 06 10 96 02: 26PM PO02 #24 R 98% 17 4 1 0 9 5 5 1 6 1 1 06 10 96 02: 26PM P O 0 3 #2 4 18 R= 98% 4 1 0 9 5 5 1 8 1 1 0 6 1 0 9 6 0 2 : 26Pl. f PO04 S24 19 4 1 0 9 5 5 1 8 1 1 0 6 1 0 9 6 02: 26PM PO05 #2 4 /

R 98% 20 4 1 0 9 5 5 1 8 1 1 06 10 96 02: 26PM PO06 #24 .  . ." .. Figure 1 I URBAN HEAT Heat related ISLAND EFFECT Respiratory dims Dengue €4 DHF Encephalitis Malaria Lyme disease Yellow fever Toxic algae & cholera

Malnutrition & immunosuppres sion se Diarrheal & vector

Lost public health infrastructure DISASTERS 5 bme. diseases, &

Overcrowding, poor disease & impacts on fisheries SEA LEVEL sanitation, infectious OZONE DEPLrnON Skin Cancers imrnuno suppression UV 8 Radiation  Ocular cataracts Anficlgated causal pathways of public health impacts from climate change. Adapted from: Patz & Balbus. Methods for assessing public health vulnerability to climate change. Climate Research 1996; 6: 1 13 1 25.

R 98% 4 1 0 9 5 5 1 8 1 1 06 10 96 02: 26PM PO07 #24 Leishmaniasis Onchcroeniasis (River Blindness)

Ycllaw Fever 9 173 miUian Tropi ics Tropialhfrica Africahatn Amcrica Ccntnl and SoUthAmtrica c R 97% 4109551811 06 10 96 02: 26PM PO08 #2 4 Figure 2 r

4 1 0 9 5 5 1 8 1 1 . ... .. OE 10 96 0 2 : 26PM PO09 #24 . A .

TESTIMONY OF GARY S. GUZY GENERAL COUNSEL U. S. ENVIRONMENTAL PROTECTION AGENCY SUBCOMMITTEE GN NATiONAL ECONOMIC GROWTH, NATURAL RESOURCES'AND REGULATORY AFFAIRS OF THE COMMITTEE ON GOVERNMENT REFORM AND THE SUBCOMMITTEE ON ENERGY AND ENVIRONMENT OF THE COMMITTEE ON SCIENCE U. S. HOUSEQF REPRESENTATIVES ,/

 . BEFORE A JOINT HEARING OF THE October 6,1999 Thank you, Chairman McIntosh, Chairman Calvert, and Members of the Subcommittees, for the invitation to appear here today. I am pleased to have this

opportunity to explain the U. S. Envifonmental Protection Agency's (EPA) views as to the legal authority provided by the klean Air Act (Act) to regulate emissions of carbon dioxide, or CO,.

Before I do, however, 1 would like to stress, as EPA repeatedly has stated in letters to Chairman McIntosh and other Members. of Congress, that the Administration has no intention of imple irmting the Kyoto Protocol to the United Nations Framework Convention on CIimte Change prior to its ratification with the advice and consent of the Senate. ' As I indicated in my letter of September 17, 1999 to Chairman McIntosh,

' S e e , e. g., Letter f r m Gz y S. C L ' Z ~, Gcnerel Counse!, to Consressman ~a!; id McIntosh, September 17, 1999; Letter from David Gardiner, Assistant Administrator for Policy, to Congressman David McIntosh, June 23, 1999; Letter from David Gardiner, Assistant Administrator for Policy, to Congressman David Mclntosh, August 13, 1988.

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there is a clear differL., ce between actions that carry out a. .rarity under the Clean Air Act or other domestic law, and actions that would implement the Protocol. Thus, there is nothing inconsistent in assessing the extent of current authority under the Clean Air * *

Act and maintaining our commitment not to implement the Protocol without ratification:

Some brief background information is helpful in understanding the context for this question of legal authority. In the course of generating electricity by burning fossil fuels, electric power plants emit into the air multiple substances that pose environmental concerns, several of which .are already subject to some degree of regulation. Both industry and government share an interest in understanding how d different pollution control strategies interact. These interactions are both physical (strategies for controlling emissions of one substance can affect emissions of others)

and economic (strategies designed to address two or more substances together can cost substantially less than strategies for individual pollutants that are designed and

i'

implemented independently). EPA has worked with a broad array of stakeholders to evaluate multiple pollutant control stra. tegies for this industy in a series of forums,

dating back to the Clean Air Power initiative (CAPI) in the mid 1990s. While the CAP1 process focused on SO2 and NOx, a broad range of participants, including representatives of power generators, the United Mine Workers, and environmentalists,

expressed support for inclusion of CO2'emissions; aiong with S02, NOx, and mercury,

in subsequent analyses. One conclusion that emerged from these analytical efforts is that integrated strategies using market based "cap and trade" approaches like the 2 > ,/ ' i . ,.". ,  program currently in ,. ace to address acidrain would be t i . most flexible and lowest cost means to control multiple pollutants from these sources.

6 6 OnM5rch 1 I, 1998, during hearings on EPA's FY 1999 appropriations;

Representative CeLay asked thz Administrator whether she believed that EPA had .

authority to regulate emissions of pollutants of concern from electric utilities, including CO,. She replied that the Clean Air Act provides such authority, and agreed to Representative DeLay's request for a legal opinion on this point.

Therefore, my predecessor, Jonathan Z. Cannon, prepared a legal opinion for EPA Administrator Carol Browner on tfe question of EPA'S legal authority to regulate several pollutants, including CO, emitted by electric power generation sources. The legal opinion requested by Rep. Delay was completed on April I O , 1998. It addressed the Clean Air Act authority to regulate emissions of four pollutants of concern from .

electric power generation: nitrogen dxides (NO,,, sulfur dioxide (SO,), mercury, and .

C O , Because today's hearing is focused exclusively on CO,, 1 will summarize the

opinion's conclusions only as they relate to that substance.

The Clean Air Act includes a definition of the term "air pollutant, '' which is the touchstone of EPA's regulatory authority over emissions. Section 302( g) defines "air pollutant" as ,.

any air pollution agent or Combination ofsuch agents, including any physical, chemical, biological, [or] radioactive . . . substance or matter which is emitted into or otherwise enters the ambient air. Such term includes any precursors to the . '

formation of any air pollutant, to the extent that the Administrator has identified such precursor or precursors for the particular purpose for which the term "air pollutant" is used,

Mr. Cannon noted that CO, is a "physical [and] chemical substance which is emitted 3  .. :. . .. .. .  . .. . . .. ..  into ... the ambient all , ' and t h u s is an "air pollutant'' withi,. .ne Clean Air Act's (.

definition. Congress explicitly recognized emissions of CO, from stationary sources,

such as fossiifuel power plants, as an "air pollutant" in Section 103( g) of the Act, which 4 4 authorizes EPA to cocduct a basis research and technology program to include, among other things, "[ i] mprovements in nonregulatory strategies and technologies for preventing or reducing multiple air pollutants, includinq sulfur oxides, nitrogen oxides,

heavy metals, PM 10 (particulate matter), carbon monoxide, and carbon dioxide, from stationary sources, including fossil fuel power plants." (Emphasis added.) 4 The opinion explains'further that the status of CO, as an "air pollutant" is not changed by the fact that C02 is a constituent of the natural atmosphere. In other words,

a substance can be an "air pollutant" under the Clean Air Act's definition even if it has natural sources in addition to its man made sources. EPA regulates a number of

~. ..... .. .. . .. i ." ,.  .. .. naturally occurring substances as ai; pollutants because human activities have . .

increased the quantities present in the air to levels that are harmful to public health,

welfare, or the environment. For example, SO, is emitted from geothermal sources;

volatile organic compounds. (VOCs), which are precursors to harmful ground level ozone, are emitted by vegetation. Some substances regulated under the Act as hazardous airpollutants are. actually necessary in trace quantities forhuman life, but are tokk at higher levels orthrough otherroutes of exposure. Manganese and i:". .i_ .. `

selenium are two examples of such pollutants. Similarly, in the water context,

phosphorus is regulated as a pollutant because although it is a critical nutrient for plznts, in excessive quantities it kills aqugtic life in lakes and other water bodies. ..

4 ~. .............. .. ,... ........ ...... ...... L. ............ .. _:. . . : ..: . . .. ...... . . .. ...... .. . .+, x.. . i While CO,, a, A n "air pollutant," is within the sc0pL ~f the regulatory authority provided by the Clean Air Act, this by itself does not lead to regulation. The Clean Air Act includes3 number of regulatory provisions that may potentially be applied to an air a pollutant. But before EPA can actt~ ally iswe restilations governing a polhtant, the Administrator must first make a formal finding that the pollutant in question meets specific criteria laid out in the Act as prerequisites for EPA regulation under its various provisions. Manyof these specific Clean Air Act provisions for EPA action share a common feature in that the exercise of EPA's authority to regulate air pollutants is linked to a determination by the Administrator regarding the air pollutant's actual or 9 potential harmful effects on public health, welfare or the environment. For example,

EPA has authority under section 109 of the Act to establish National Ambient Air Quality Standards for any air pollutant for which the Administrator has established air quality criteria under section 108. U$ der section 108, the Administrator must first find

that the air pollutant in question meets several criteria, including that:

 it causes orcontributesto" airpollutionwhichmay reasonably be anticipated to endanger public health or welfare;" and  its presence in the ambientair'" resu1tsfromnumerous or diverse mobile or stationary sources ... .'I Section 302( h), a provision dating back to the 1970 version of the Clean Air Act, defines "welfare" and states:

all language referring to effects on welfare includes, but is not limited to, effects on soils, water, crops, vegetation, man made materials, animals, wildlife, weather, visibility, and climate, damage to and deterioration of property, and hazards io transpofiation, 2s L V ~ as &ki= ts on econcnic va! ves and on person?! comfort and well beim! whether caused by transformation., conversion, or combination with other air pollutants.

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Thus, since 1970, t h t Jean Act has included effects on considered in the Administrator's decision as to whether section 108. * ,/

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"c,. .late" as a factor to be to list an air pollutant under Analogous threshold findings sre required before the Administrator may establish new source performance standards for a pollutant under section 11 1, list and regulate the pollutant as a hazardous air pollutant under section 112, or regulate its emission from motor vehicles under Title I I of the Act.

Given the clarity of the statutory provisions defining "air pollutant" and providing '4 authority to regulate air pollutants, there is no statutory ambiguity that could be clarified by referring to the legislative history. Nevertheless, I would note that Congress'

decision in the 1990 Amendments not to adopt additional provisions directing EPA to regulate greenhouse gases by no means suggests that Congress intended to limit a

existing authority to address any aicpollutant that the Administrator determines meets the statutory criteria for regulation under a. specific provision of the Act.

I would like today to reiterate one of4he central conclusions of the Cannon memorandum, which stated: "While CO,, as an air pollutant, is within EPA's scope of authority to regulate, the Administrator has not yet determined that CO, meets the criteria for regulation .under one or more provisions of the Act." That statement remains true today. EPA has not made any of the. Aet's threshold findings that would lead to regulation of CO, emissions from electric utilities or, indeed, from any source. The opinion of my predecessor simply clarifies  and I endorse this opinion  that CO, is in the class of compounds that coulcl be subject to several of the Fiean Air A& s ....

regulatory approaches. Thus, I would suggest that many of the concerns raised about 6 .. .... ... ..... ... __ .... . .. ..

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t h e statutory authority [o address CO, relate more to factuGl and scientific, rather than legal, questions regarding whether and how the criteria for regulation under the Clean a * Air Act could be satisfied.

1 also want to notq however, EPA has strongly promoted voluntary partnerships to reduce emissions of greenhouse gases through the EnergyStar and Green Lights programs and other non regulatory programs that Congress has consistently supported.

These successful programs already have over 7,000 voluntary partners who are taking steps to reduce greenhouse gas emissions, reduce energy costs and help address local air pollution problems. These programs also help the United States meet its 3 obligations under the United Nations Framework Convention on Climate Change, which was ratified in 1992. I would also note, as EPA has indicated in past correspondence with Chairman McIntosh and others, in the course of carrying out the mandates of the Clean Air Act, EPA has in a few insiances directly limited use or emissions of certain

greenhouse gases other than CO,. .For example, EPA has limited the use of certain substitutes for ozone depleting substances under Title VI of the Act, where those substitutes have very high global warming potentials. i wish to stress once more,

however, that while EPA will pursue efforts to address the threat of global warming through the voluntary programs authorized and funded by Congress and will carry out the mandates of the Clean Air Act, this Administration has no intention of implementing the Kyoto Protocol prior to its ratification on the advice and consent of the Senate,

This concludes my prepared sistment. I would be happy to mswer any questions that you may have.

7 APR I 0 1 9 5 8 MEMORANDUM 1. Xntmduction and Background c, I,.

A Definition of Air PoHutant my air pollution agent or combination of such agents, including any physical, chcrnical, bjologd, [or3 radioactive  . . substance or matter which is crnittcd into or othwisc emers the ambieht air. Such tern includcs any precursors to the formation of any air pohtanr, to the e x t e n t that thc Administtaror has idemifiicd such precursor or prtcursors for the particular purpose for which the term "air pollutant" i s used.

This broad definition states that "air pollutant" includes any physical, chemic& biologjtaj, or radioactive substance ctr matter that is emitted into or otherwise enters the ambient air. so,, NO,, CO, and mercury from ciectric power gcncration Ere each a "physical [and] chemicd , , .

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