The Thermometer Series: The first of six articles on the next steps in climate reform and why we need to advance current climate change strategy.


The driver of our climate system has changed in the last two decades from one that is controlled by annual emissions, to one that is controlled by already emitted CO2. This means that previous strategies to control annual emissions are no longer meaningful and we must now turn our attention to the already emitted climate pollution.

The cost of not emitting our annual load of CO2, at two percent of global GDP annually, is about $750 billion per ppm CO2 of CO2 emissions avoidance. The cost of direct air capture of CO2 (DAC) at $20 per ton is $160 billion per ppm, or only 20 percent the cost of emissions reductions. At $10 per ton it is $80 billion per ppm, or ten percent of what we would spend using strategies we have been unsuccessfully trying to implement for a generation.

Even 80 percent emissions reductions–if we can ever get them implemented–allow atmospheric CO2 to continue to increase until 2050, and warming up to triple what we have already endured.

Considering the risk implicated by the latest “next generation” ice sheet collapse modeling and NOAA’s suggestion that near future modeling will show the West Antarctic Ice Sheet will contribute 10 feet to sea level rise by 2050 unless warming is returned to zero by that time, our ultimate success cannot come too soon. The cost of not succeeding, considering sea level rise alone, will not just be the submergence and collateral damage to some 30 percent of global wealth (about $75 trillion), but a complete collapse of the global economy.

“All we have to do” (and I was recently berated by one of my editors for using this brain science statement in this context) is give ourselves permission to abandon emissions reductions strategies of the past and pursue a much more economic course of action to address climate pollution.

Now… A very important note: Abandoning previous climate control strategies absolutely does not mean rampant fossil fuel abuse for two reasons.

1) We have existing mechanisms in place to regulate the abuses of the fossil fuel industrial complex (air pollution, health impacts, water and environmental degradation.) These need continued work, but are already in existence, have been in existence generally for generations, and new ones (fracking) are rapidly coming onboard using the existing mechanisms for environmental protection regulation creation. (Methane from fracking, permafrost, and clathrates are serious threats and must be evaluated relative to climate change risks with urgency so that our future climate does not change again, to a system that is controlled by methane and not CO2.)

2) Solar energy: Cheaper than the cheapest fossil fuel energy already, will organically reduce annual CO2 emissions at what will likely be a surprising rate–beginning a few to several years ago.


$20 trillion for 50 ppm CO2 at $55 per ton:
Hansen et al., Target Atmospheric CO2 Where Should Humanity Aim? Open Atmospheric Science Journal, November 2008,  page 226 and 227, Section 4.4 Policy Relevance, paragraph 1. Hansen describes the cost of carbon removal at $200 per ton or less which is $55 per ton CO2.

$750 billion per 1 ppm using emissions reductions (emission avoidance):
Three are 7.81 gigatons of tons of carbon dioxide per ppm CO2 in the atmosphere.

Cost of emissions avoidance at 2 percent global GDP:

There are many sources here with a confluence at about two percent global GDP being what is needed to effect what were once meaningful emissions reductions. Probably the most authoritative is Stern.
Stern Review: The Economics of Climate Change, HMS Treasury, October 2006. Summary of Conclusions, paragraph 6.
In 2008, Stern revised his costs upwards from 1 percent in his 2006 report to 2 percent:

Emissions Reductions vs. Emissions Avoidance; The Tricky Part — Getting from our annual 40 GT CO2 emissions to 2 ppm CO2 avoidance:
Today’s 40 gigatons of annual CO2 emissions are equal to about 5 ppm CO2, but half of all emitted CO2 is either quickly absorbed by oceans and plants or elsewise done away with chemically in the sky. So 100 percent emissions reductions means that we see half of the CO2 we emit remaining in the atmosphere in the long-term. This is why the increase in atmospheric CO2 (see Mauna Loa CO2) has only just recently bumped up above 2 ppm CO2 per year and one of the hidden reasons why emissions reductions are folly — we have to reduce emissions by double what we would be the same removal from the sky. Also assumed is that future CO2 emissions reductions will only fall from our current 2 ppm per year level. The reason is solar energy. Fossil fuels cannot compete. They are doomed naturally because a newer, better, cheaper energy source has arrived.

Discussion of: “about half of all CO2 is absorbed rapidly.”
Once CO2 emission happen, it immediately begins to be sucked back out of the sky or chemically changed to something different from CO2. The process starts off very rapidly and ends very, very slowly. Most of it is absorbed by our oceans, plant materials and soils. About half of our emissions of CO2 stay in the atmosphere for 3 or 4 years before being assimilated; 17–33% will still reside in the atmosphere 1,000 years from now, 10–15% at 10,000 years, and 7% remains after 100,000 years.

Yale describes what is labelled the CO2 atmospheric residence time and its complicating issues.

The Details:
Archer, Fate of Fossil Fuel CO2 in geologic time, Journal of Geophysical Research, vol 110, 2005.

Direct Air Capture (DAC):
$200 or less per ton Carbon, or $55 per ton CO2 is from Hansen’s Target Atmosphere CO2 (2008) referenced above.
From Hansen 2008: The references for “$200 per ton or less” from Hansen 2008 are:
Keith DW, Ha-Duong M, Stolaroff JK. Climate strategy with CO2 capture from the air. Clim Change 2006; 74: 17-45.
Lackner KS. A guide to CO2 sequestration. Science 2003; 300: 1677-8.

DAC costs–Other Lines of Research:

Direct air capture (DAC) costs… Goeppert et al., produced a literature summary of current DAC findings in 2012. It is important to note that considerable false propaganda has been circulated in the media about the infeasibility of DAC based on a report by the American Physical Society. Discussion of this apparent controversy is given below highlights of Geoppert 2012.
Abstract only:!divAbstract

$20 per ton (just over) capture and storage… Section 5.10 paragraph 2, “using the K2CO3/KHCO3 cycle is described as being able to capture CO2 from air for less than $20 per ton. The total cost including sub-surface injection was estimated to be slightly above $20 per ton.” COAway LLC

$49 to $80 per ton… Section 5.10 paragraph 3: “An air capture system designed by Keith et al. using a Na/Ca cycle was estimated to cost approximately $500 per ton C ($140 per ton CO2).81,98 The authors added that about a third of this cost was related to capital and maintenance cost. Further development and optimization of the system by Carbon Engineering Ltd.113 for the effective extraction of CO2 from air resulted in the decrease of the estimated cost to $49–80 per tonne CO2.” Keith, Ha-Duong and Stolaroff, Clim. Change, 2006, and Stolaroff, Capturing CO2 from ambient air: a feasibility assessment, PhD thesis, Carnegie Mellon University, Pittsburgh, PA, 2006.

$53 to $127 per ton… Section 5.4.1, second paragraph: “The cost of CO2 capture in this case (excluding CO2 solution recovery and utilization or sequestration) was estimated to be between $53 and $127 per ton of CO2 depending on operating conditions, capital costs and mass transfer rate.” Stolaroff, Keith and Lowry, Environ. Sci. Technol., 2008.

$30 per ton long term… Section 5.10, paragraph 5: “Lackner and co-workers developed an anionic exchange resin able to release CO2 in a moisture swing process. The cost of only the energy required per ton of CO2 collected was around $15. The initial cost of air capture including manufacturing and maintenance can be estimated at about $200 per ton of CO2. However, this cost is expected to drop considerably as more collectors are built, possibly putting CO2 capture in the $30 per ton range in the long term.” Lackner, Eur. Phys. J. Spec. Top., 2009, 176, 93–106. Lackner, Sci. Am., 2010, 66–71.


Bonus: $10 per ton using waste heat…

Global Thermostat — Graciela Chichilnisky’s Presentation, slide 7, $10 per ton using waste heat at 50 degrees C and at industrial scale, $50 per ton today with Global Thermostat’s pilot project.

More on costs:

$400 billion per ppm:
Hansen’s $20 trillion for 50 ppm CO2 is $400 billion per ppm. Note: This is a worst-case scenario. So far, only the American Physical Society and MIT say costs are higher and they base their assumptions on inaccurate science or poor evaluation comparisons as described in the section below on the DAC Controversy. Otherwise, costs peak at about $150 per ton. The important part here is that industrialization, in our society today, has a way of really knocking down the cost of anything and everything that comes its way. The papers that talk about future industrialization are in the $20 to $30 dollar per ton range.

$20 per ton, $160 billion per ppm:
The great part about this math is that Global Thermostat has already surpassed it with waste heat. Planning today for a zero warming planet must include energy costs for future solar in the sub $0.01 per KWH range. Energy costs assumed in all of the previous work on DAC is from the 2000s and is in the $0.06 to $0.10 per KWH range. And the great part, to be clear, is not really that we can save our planet with cheap solar energy, it’s that energy costs in the future are going to really, really, (this time) be almost too cheap to meter!

Caveat –Important–
As atmospheric CO2 comes down because of DAC, CO2 will begin to come out of the oceans directly into the atmosphere because the ocean/atmosphere CO2 equilibrium will have changed. This means that removing 50 ppm CO2 from the sky will not result in atmospheric CO2 falling an equal amount. But because only ocean water near the surface, or that part of the oceans where mixing brings ocean water into contact with the surface, is involved with this equilibrium shift, not all of the excess CO2 buried by the oceans will return to the atmosphere quickly. As a gross concept, the global thermohaline circulation takes about 1,000 years to make one lap around world and half this time it circulates on the bottom of the ocean making it unavailable to mix with surface waters. Therefore, much of the excess CO2 absorbed by the oceans therefore is locked up for time frames that matter.

DAC Controversy:

The American Physical Society (APS) study and (MIT’s) similar work from 2011 looks at the basic physics and  mature DAC technology (WWII) of capturing CO2 with NaOH (sodium hydroxide) from flue gas. Because of the outsized capacity for DAC to solve the climate pollution problem, the APS and MIT findings garnered very significant press as they state the costs of DAC to be $600 to $1000 per ton or 20 to 50 times greater than what the new technology DAC researchers suggest. Their basic reasoning quotes basic physics and that the low concentration of CO2 in air is much harder to address than higher flue gas concentrations from power plant smokestacks. But APS and MIT did not evaluate the new technologies, they only looked at the WWII era NaOH process. Press coverage did not mention that new technologies were not evaluated, or that APS and MIT had made basic physics errors in enthalpy. Several academic rebuttals did not make the news cycle and as a result, climate advocates, the public, and policy makers believe that the APS and MIT work is valid and DAC of carbon dioxide is cost prohibitive.

To their credit, and to the media’s discredit, APS and MIT works caveated appropriately saying they only evaluated mature processes and new technologies could be game changers. But more important, their basic physics was flawed as was pointed out by Realff and Eisenberger 2012. When valid physics is evaluated, the costs of new technology DAC is very similar to what the physics shows (see also Holmes and Kieth 2012.)

None of the rebuttal work was captured in the media cycle though. This could have been because of the Climate Change Counter Movement (Brulle 2013) pushing the “infeasible” research, or simply because the media news cycle is fickle and prone to skip what is perceived as less important news when other news is seen as a priority during any specific news cycle. Regardless, the damage was done and even most climate scientists understand only what was captured in the media cycle and not the underlying science because, digging out the underlying science is simply not a priority for most climate scientists who focus their energies on other disciplines. They trust the media with all of its bias and this trust finds its way into other academic work and policy because of the general authority of all climate scientists relative to climate issues.

American Physical Society Study…
Socolow et al., Direct Air Capture of CO2 with Chemicals, The American Physical Society, June 2011.

APS research revealed as significantly incomplete by Nature… Socolow 2011 evaluated existing WWII Era atmospheric removal techniques and not surprisingly found them economically infeasible to address climate pollution. New technologies were not evaluated. The Climate Change Counter-Movement widely circulated the APS study and even though the third most important scientific journal in the world refuted APS claims—because they did not evaluate current new technologies—the damage was done; the media cycle has run its course. Today DAC is almost completely discredited in climate pollution mitigation strategies considered by policy makers and advocates, regardless of academic findings counter to this understanding.  
Van Norden, Sucking carbon dioxide from air too costly, say physicists, Nature, May 11, 2011.

Evaluates only mature technologies (House 2011)…
House et al., economic and energetic analysis of capturing CO2 from ambient air, PNAS, September 2011.

Further rebuttal of APS and MIT (Holmes and Keith 2012)…
Holmes and Keith identify short fallings of MIT and APS work calling out different design choices, insufficient optimization, and use of higher cost processes. When new DAC technologies are evaluated, costs are at or below those of mature DAC removal technology.
Holmes and Keith, An air-liquid contactor for large-scale capture of CO2 from air, Philosophical transactions of the Royal Society A, 370, 4380-4403, 2012.

Flawed analysis of the Basic physics of enthalpy (Realff and Eisenberger 2012)…
These researchers point out a fundamental flaw in the work of APS and MIT showing direct air capture takes more energy than flue capture because of CO2 concentration: “The notion of minimum work does not apply to the capture of CO2, because the capture process is exothermic.” When CO2 is reacted with something to remove it from air or flue gas, the reaction creates heat, “is exothermic.” So instead of 400 kJ or work per mole CO2 energy required the actual energy required involves moving air over whatever process is used to remove the CO2 from the air. This is 6 kJ per mole CO2. This relationship of the actual costs of removal of CO2 from the atmosphere being 1.5 percent of the costs suggested by APS and MIT corresponds very well to the costs assumed by research evaluating new technologies of +/- $20 per ton. It is important to note that the cost of regenerating the chemicals used to capture the CO2, whether for flue gas or atmospheric capture, is identical.
Realff and Eisenberger, Flawed analysis of the possibility of air capture, June 19, 2012.