Media coverage of NAS “Climate Intervention” reports

February 10, 2015

On February 10, The National Research Council wing of the The National Academies of Sciences released two reports, Climate Intervention: Carbon Dioxide Removal and Reliable Sequestration, and Climate Intervention: Reflecting Sunlight to Cool Earth.  They are interesting reports!  They are also 135 and 235 pages long! You can find them in full here. The full text of the press release, which gives good context for how the study was conducted, what it covered and what it aimed to accomplish, along with an overview of the major findings as presented by the study’s authors, can be found at the bottom of this post.

There was a lot of press coverage of the reports and the event marking their release.  We’re doing everyone a favor and rounding up some of the major pieces.  [Updating as needed]

Panel Urges More Research on Geoengineering as a Tool Against Climate Change– New York Times.  Henry Fountain writes “The panel said the research could include small-scale outdoor experiments, which many scientists say are necessary to better understand whether and how geoengineering would work.”

David Keith, a researcher at Harvard University who reviewed the reports before they were released, said in an interview, “I think it’s terrific that they made a stronger call than I expected for research, including field research.” Along with other researchers, Dr. Keith has proposed a field experiment to test the effect of sulfate chemicals on atmospheric ozone.

Scientists Suggest Testing Climate Engineering – MIT Technology Review.  Kevin Bullis writes that “A report from the National Academy of Sciences says inaction on greenhouse-gas emissions makes resorting to geoengineering more likely.”

David Victor an expert on climate policy from the University of California at San Diego, says it would be best to start the research and develop policies along the way. At this point, Victor says, too little is known for a serious discussion to begin. “No one would know what they were negotiating,” he says.

Climate Hacking is Barking Mad – Slate.  Raymond T. Pierrhumbert writes that “You can’t fix the Earth with these geoengineering proposals, but you can sure make it worse.”

When has humanity managed to sustain a concerted complex technological enterprise for centuries, let alone millennia?

Top U.S. scientists urge pursuit of technology to cool planet – L.A. Times.  Ralph Vartabedian & Evan Halper write “A panel of the nation’s top scientists say the time has come to significantly increase research efforts and prepare to step in should there be a climate catastrophe.”

Let’s hope it never happens, but if we ever have our back against the wall we will know ahead of time what we need to do,” said Marcia McNutt, chair of the committee and editor in chief of Science magazine.

Scientists urge global ‘wake-up call’ to deal with climate change – The Guardian.  Suzanne Goldenberg writes “Climate change has advanced so rapidly that work must start on unproven technologies now, admits US National Academy of Science.”

It’s hard to unthrow that switch once you embark on an albedo modification approach. If you walk back from it, you stop masking the effects of climate change and you unleash the accumulated effects rather abruptly,” Waleed Abdalati, a former Nasa chief scientist who was on the panel, said.

Elite science panel calls on U.S. to study climate modification – The Washington Post. Chris Mooney writes “The first thing to understand about geoengineering – intentional modification of the climate system to counter the effects of global warming – is that we shouldn’t even be having a conversation about geoengineering.”

“The Committee argues that, as a society, we have reached a point where the severity of the potential risks from climate change appears to outweigh the potential risks from the moral hazard associated with a suitably designed and governed research program.”

In Geoengineering Study, Science Academy Sees Merit in CO2 Removal, Risk in Reflecting Sunlight – Dot Earth (New York Times). Andrew Revkin says “The panels’ overarching bottom line is straightforward: There is no substitute for dramatic reductions in the emissions of CO2 and other greenhouse gases to mitigate the negative consequences of climate change, and concurrently to reduce ocean acidification.”

There are no big surprises in the voluminous reports, but they do provide a great guide to both the scientific and societal issues attending using “climate interventions” — the reports’ phrase for geoengineering techniques — to counter humanity’s continuing intervention: the release of tens of billions of tons of carbon dioxide a year.

Report: Don’t Try to Block the Sun to Fix Climate Change – The National Journal. Jason Plautz writes “Geoengineering solutions for global warming not ready for prime time.”

Rafe Pomerance, a former State Department climate official who was not involved in the NRC report, said in an interview that with extreme storms and sea-level rise showing the growing risk of climate change, the time is ripe to put every option on the table.

U.S. should fund climate engineering research, report concludes – Science Magazine. Eli Kintisch reports “The recommendations, found in a two-volume report released today,move the so-called geoengineering techniques, long verboten among scientists, one step closer to the mainstream.”

It’s telling that the new climate engineering report didn’t come via request from federal science agencies. Rather, in 2013 the CIA requested the report. But scientists told NRC it should get civilian agencies involved. “You don’t want this topic militarized,” Keith says. Ultimately, NASA, DOE, and the National Oceanic and Atmospheric Administration together paid for roughly 10% of the report’s cost.

Geoengineering: The Bad Idea We Need to Stop Climate Change – Eric Roston writes “The National Research Council has provided a shock of fresh air to the climate debate in the U.S.”

The NRC reports should allow many people to hear about geoengineering for the first time. That’s a good thing because it offers a new approach to talking about climate change, beyond the impoverished and mendacious conversation U.S. politicians have been having for 20 years. Geoengineering is new and promising enough to overcome some of the culture-based polarization that dominates public discussion of the issue.

Geoengineering Holds Promise; Solutions Not Ready – Climate Central. Brian Kahn writes “Just five years ago, President Obama’s science advisor said that geoengineering has “got to be looked at.” On Tuesday, a report funded by federal agencies and released by the non-profit National Academy of Sciences (NAS) provided a detailed look at the state of geoengineering and suggests how the government could develop a program to better understand the consequences of further planetary tinkering, including small-scale tests.”  

“If CO2 emissions were declining rapidly, I don’t think there would be that much impetus behind dong a report like this. There’s a question about what would we do if things start getting worse, if climate change leads to some kind of crisis situation,” Ken Caldeira, one of the report’s authors and a researcher at the Carnegie Institute for Science, said.

Controversial Method Of Addressing Climate Change Needs More Study, Experts Say –Huffington Post. Kate Sheppard reports “Taken together, the reports suggest that more research and even some testing of these types of climate intervention methods are needed to understand their potential benefits and drawbacks, as well as the governance challenges if some countries or actors decide to take them on unilaterally.”

Nicholson emphasized the need for caution going forward.  “It makes far more sense,” he said, “to keep carbon dioxide out of the atmosphere in the first place than it does to put faith in speculative schemes to draw down carbon once it has already been emitted.”

Fed report: Time to examine purposely cooling planet idea – A.P. Seth Borenstein writes “It’s time to study and maybe even test the idea of cooling the Earth by injecting sulfur pollution high in the air to reflect the sun’s heat, a first-of-its-kind federal science report said Tuesday.”

“Yes, small scale outdoor tests might be allowed, but it wouldn’t just be in the hands of scientists to decide what’s allowable and what’s not allowable,” McNutt said. “Civil society needs to engage in these discussions where the line is to be drawn.”

Climate geoengineering schemes come under fire– Nature. Alexandra Witze writes “Influential US group lays out which planet-cooling proposals may work — and which won’t.”

“The biggest thing about the report is that the government asked for it,” says Jane Long, former associate director for energy and the environment at the Lawrence Livermore National Laboratory in Livermore, California, and author of a recent Nature commentary on geoengineering. “That is really important, because it legitimizes the discussion.”

Scientists Are Pretty Terrified About These Last-Minute Fixes to Global Warming – Mother Jones. Tim McDonnell writes “The most comprehensive study to date on geoengineering says we probably shouldn’t do it—at least not yet.”

“We definitely don’t think that we’re ready to say this is something worth doing,” said atmospheric chemist Lynn Russell of the University of California, San Diego, a lead author on one of the report’s volumes.

National Academy: There’s a Good and a Bad Way to “Geoengineer” the Planet– National Geographic.  Craig Welch reports “Fighting climate change by pulling CO₂ out of the atmosphere makes sense, an expert committee says. Blocking the sun, not so much.”

Six years after a report from the Royal Society in the United Kingdom reached many of the same conclusions, the American scientists decided to issue two reports—to distinguish as forcefully as they could between two very different approaches that for years have been lumped together under the heading “geoengineering.”

Climate Geoengineering: ‘Scary’ Idea Should Be Tried Out – NBC News.  “It’s time to study and maybe even test the idea of cooling Earth by injecting sulfur pollution high in the air to reflect the sun’s heat, a first-of-its-kind federal science report said Tuesday.”

It could be a relatively cheap, effective and quick way to cool the planet by mimicking the natural effects on climate of large volcanic eruptions, but scientists concede there could be dramatic and dangerous side effects that they don’t know about. Because warming has worsened and some countries might act unilaterally, scientists said research is needed to calculate the consequences.

Hack the planet? Comprehensive report suggests thinking carefully first – Ars Technica.  John Timmer writes “Geoengineering for climate change could make an expensive mess.”

“All told, the report concludes that “there is significant potential for unanticipated, unmanageable, and regrettable consequences in multiple human dimensions from albedo modification at climate altering scales.” It urges against deploying it at this time and recommends caution about doing any research on it. Any tests have the potential to bring these consequences to any nations near the test site—bad on their own, and made worse by the fact that we have nothing in the way of an international political structure to manage the ensuing problems.” 

National Academy: Geoengineering No Substitute for Carbon Cuts – Inside Climate News.  Katherine Bagley writes “The idea of geoengineering to reverse climate change has been around since the 1960s. The two-volume NAS report says cutting GHGs is the only solution.”

“The top line message from the report is pretty clear: there’s no climate engineering technology that would be a substitute for large-scale mitigation,” said Simon Nicholson, co-director of American University’s Forum for Climate Engineering Assessment who did not contribute to the report.

Scientists: We Cannot Geoengineer Our Way Out of the Climate Crisis – The Nation.  Zoë Carpenter writes “Why not, some scientists have asked in the decades since, counter climate change by reproducing the effects of Mount Pinatubo—for example, by flying a plane into the stratosphere and spraying enough sulfate aerosols to turn down the sun?”

And yet the assumption that research won’t lead to implementation is troubled by history, as Naomi Klein points out in This Changes Everything; she references the bombing of Hiroshima and Nagasaki less than a month after the first successful nuclear test. “It may start with just checking the deployment hardware, but how long before the planet hackers want to see if they can change the temperature in just one remove, low-population location… and then one a little less remote?” Klein writes.

Anti-‘Geoengineering’ National Academy Report Opposes ‘Climate-Altering Deployment’ – Climate Progress. Joe Romm writes “The U.S. National Academy of Sciences has released two very pessimistic reports on geoengineering.”

These mammoth reports can be summarized with a paraphrase of a line attributed to Samuel Johnson, “Your proposed climate intervention strategies are both safe and affordable. But the strategies that are safe are not affordable, and the strategies that are affordable are not safe.”

Geoengineering won’t solve climate change: Our view – USA Today. The USA Today Editorial Board write “As a National Academy of Sciences panel reported last week, solar geoengineering is no substitute for efforts to reduce greenhouse gas emissions and adapt to a changing climate.”

As for injecting particles into the atmosphere to cool the planet, the scientists recommended more research to determine whether such ideas could be viable someday. That’s fine, as long as policymakers treat particle injection as a last-ditch scheme that is less Plan B than it is Plan Z.”


“NAS Press Release”

Climate Intervention Is Not a Replacement for Reducing Carbon Emissions;

Proposed Intervention Techniques Not Ready for Wide-Scale Deployment

WASHINGTON – There is no substitute for dramatic reductions in greenhouse gas emissions to mitigate the negative consequences of climate change, a National Research Council committee concluded in a two-volume evaluation of proposed climate-intervention techniques.  Strategies to remove carbon dioxide from the atmosphere are limited by cost and technological immaturity, but they could contribute to a broader portfolio of climate change responses with further research and development.  Albedo-modification technologies, which aim to increase the ability of Earth or clouds to reflect incoming sunlight, pose considerable risks and should not be deployed at this time.

Carbon dioxide removal and albedo-modification techniques have been grouped up to now under the common term “geoengineering,” but they vary widely with respect to environmental risks, socio-economic impacts, cost, and research needs.  Carbon dioxide removal addresses the root cause of climate change — high concentrations of the greenhouse gas in the atmosphere — and generally have well-understood benefits and risks, but current technologies would take decades to achieve moderate results and be cost-prohibitive at scales large enough to have a sizeable impact.  By contrast, albedo-modification techniques would only temporarily mask the warming effect caused by high CO2 concentrations, and present serious known and possible unknown environmental, social, and political risks, including the possibility of being deployed unilaterally.

These differences led the committee to evaluate the two types of approaches separately in companion reports, a distinction it hopes carries over to future scientific and policy discussions.  In addition, the committee believes that these approaches are more accurately described as “climate intervention” strategies — purposeful actions intended to curb the negative impacts of climate change — rather than engineering strategies that imply precise control over the climate.

“That scientists are even considering technological interventions should be a wake-up call that we need to do more now to reduce emissions, which is the most effective, least risky way to combat climate change,” said committee chair Marcia McNutt, editor-in-chief of Science and former director of the U.S. Geological Survey.  “But the longer we wait, the more likely it will become that we will need to deploy some forms of carbon dioxide removal to avoid the worst impacts of climate change.”

If society ultimately decides to intervene in Earth’s climate, any actions should be informed by a far more substantive body of scientific research, including ethical and social dimensions, than is presently available, the committee said.  Decisions regarding deployment of carbon dioxide removal technologies will be largely based on cost and scalability, and research is needed to make current options more effective, more environmentally friendly, and less costly.  Conversely, any future decision about albedo modification will be judged primarily on questions of risk, and there are many opportunities to conduct research that furthers basic understanding of the climate system and its human dimensions — without imposing the risks of large-scale deployment — that would better inform societal considerations.

“If the world cannot slow emissions or the effects of climate change are more extreme or occur sooner than expected, there may be demands to pursue additional climate-intervention technologies about which scientists need a better understanding,” said National Academy of Sciences President Ralph J. Cicerone.  “Although riskier ideas to lessen the amount of energy absorbed from the sun should not be considered for deployment, they should be studied so that we can provide answers if someday these ideas begin to be considered in attempts to avert catastrophe.  These reports should guide federal agencies in supporting research on climate-intervention technologies, while keeping separate any decision-making about their implementation.”

Carbon dioxide removal and sequestration

Some carbon dioxide removal strategies seek to enhance or mimic the natural processes that already remove about half of the world’s carbon emissions from the atmosphere each year.  Environmental risks vary among the proposed technologies, but overall the risks are relatively low and generally understood.  However, most carbon dioxide removal strategies have limited technical capacity, and absent some unforeseen technological innovation, large-scale deployment would cost as much or more than replacing fossil fuels with low carbon-emission energy sources, the committee said.

.         Land-management approaches such as forest restoration and low-till agriculture are mature, readily deployable technologies with well-known environmental consequences.

.         Enhanced weathering processes on land and in the ocean to accelerate natural removal of carbon dioxide from the atmosphere have only been carried out on a limited scale with intermediate technological readiness.  Ocean-based approaches in particular carry significant environmental and socio-political risks.

.         Ocean iron fertilization is an immature technology whose high costs and technical and environmental risks currently outweigh the benefits.

.         Approaches in which biomass is converted to heat, electricity, or liquid or gas fuels followed by CO2 capture and sequestration are limited by the availability of land for biomass cultivation and the need to transport it to processing facilities.

.         Direct air capture of carbon is an immature technology with only laboratory experiments carried out to date and demonstration projects in progress.  Technologies for storing the captured carbon are at an intermediate stage, but only prototypes exist and are not at the scale required for significant sequestration.

The committee recommended federal research and development investment to improve methods of carbon dioxide removal and disposal at scales that would have a significant global climate impact.  In particular, research is needed to minimize energy and materials consumption, identify and quantify risks, lower costs, and develop reliable sequestration and monitoring capabilities.

Albedo-modification research

Technologies that prevent sunlight from reaching Earth’s surface could reduce average global temperatures within a few years, similar to the effects of large volcanic eruptions.  While many albedo-modification techniques have been proposed, the committee said two strategies that could potentially have a significant impact are injection of aerosols into the stratosphere and marine cloud brightening.  Unlike carbon dioxide removal, these methods would not require major technological innovation to be implemented and are relatively inexpensive compared with the costs of transitioning to a carbon-free economy.

However, albedo modification would only temporarily mask the warming effect of greenhouse gases and would not address atmospheric concentrations of CO2 or related impacts such as ocean acidification.  In the absence of CO2 reductions, albedo-modification activities would need to be sustained indefinitely and at increasingly large scales to offset warming, with severe negative consequences if they were to be terminated.  In addition, albedo modification introduces secondary effects on the ozone layer, precipitation patterns, terrestrial and marine ecosystems, and human health, with unknown social, political, and economic outcomes.

Many of the processes most relevant to albedo modification — such as those that control the formation of clouds and aerosols — are among the most difficult components of the climate system to model and monitor. Present-day observational capabilities lack sufficient capacity to monitor the environmental effects of an albedo-modification deployment. Improvements in the capacity to monitor direct and indirect changes on weather, climate, or larger Earth systems and to detect unilateral or uncoordinated deployment could help further understanding of albedo modification and climate science generally.

The committee said it would be “irrational and irresponsible” to implement sustained albedo modification without also pursuing emissions mitigation, carbon dioxide removal, or both.  It opposed deployment of albedo-modification techniques, but recommended further research, particularly “multiple-benefit” research that simultaneously advances basic understanding of the climate system and quantifies the technologies’ potential costs, intended and unintended consequences, and risks.

Albedo-modification research will have legal, ethical, social, political, and economic ramifications.  The committee recommended the initiation of a serious deliberative process to examine what international research governance structures may be needed beyond those that already exist, and what types of research would require such governance.  The degree and nature of governance should vary by activity and the associated risks, and should involve civil society in decision-making through a transparent and open process.

The study was sponsored by the National Academy of Sciences, U.S. intelligence community, National Aeronautics and Space Administration, National Oceanic and Atmospheric Administration, and U.S. Department of Energy.  The National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council are private, independent nonprofit institutions that provide science, technology, and health policy advice under a congressional charter granted to NAS in 1863.  The National Research Council is the principal operating arm of the National Academy of Sciences and the National Academy of Engineering.  For more information, visit  A committee roster follows.


Lauren Rugani, Media Relations Officer
Christina Anderson, Media Assistant
Office of News and Public Information
202-334-2138; e-mail

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Pre-publication copies of Climate Intervention: Carbon Dioxide Removal and Reliable Sequestration and Climate Intervention: Reflecting Sunlight to Cool Earth are available from the National Academies Press on the Internet at or by calling 202-334-3313 or 1-800-624-6242. Reporters may obtain a copy from the Office of News and Public Information (contacts listed above).


NATIONAL RESEARCH COUNCIL, Division on Earth and Life Studies, Board on Atmospheric Sciences and Climate

Committee on Geoengineering Climate: Technical Evaluation and Discussion of Impacts

Marcia K. McNutt* (chair)
Editor-in-Chief, Science
American Association for the Advancement of Science, Washington, D.C.

Waleed Abdalati
Professor, Department of Geography, and Director, Cooperative Institute for Research in Environmental Sciences
University of Colorado Boulder, Boulder

Ken Caldeira
Senior Member
Department of Global Ecology, Carnegie Institution for Science;
and Professor Environmental Earth System Sciences Department
Stanford University, Stanford, Calif.

Scott C. Doney
Senior Scientist and Chair
Department of Marine Chemistry and Geochemistry
Woods Hole Oceanographic Institution, Woods Hole, Mass.

Paul G. Falkowski*
Bennett L. Smith Professor of Business and Natural Resources
Department of Earth and Planetary Sciences,
and Lead Principal, Environmental Biophysics and Molecular Ecology Program
Rutgers University, New Brunswick, N.J.

Steven Fetter
Associate Provost for Academic Affairs, and
Professor, Maryland School of Public Policy
University of Maryland, College Park

James R. Fleming
Professor of Science, Technology, and Society,
Colby College, Waterville, Maine

Steven P. Hamburg
Chief Scientist, Environmental Defense Fund, Boston

Granger Morgan*
Lord Chair Professor in Engineering,
Professor and Department Head, Engineering and Public Policy,
Professor in Electrical and Computer Engineering, and
Professor, The H. John Heinz III School of Public Policy
Carnegie Mellon University, Pittsburgh

Joyce E. Penner
Ralph J. Cicerone Distinguished University Professor of Atmospheric Science, and
Associate Chair, Department of Atmospheric, Oceanic, and Space Sciences
University of Michigan, Ann Arbor

Raymond T. Pierrehumbert
Louis Block Professor
Department of Geophysical Sciences
Hinds Geological Laboratory
University of Chicago, Chicago

Philip J. Rasch
Chief Scientist for Climate Science
Pacific Northwest National Laboratory, Richland, Wash.

Lynn M. Russell
Professor, Climate, Ocean, and Atmosphere Program
Scripps Institution of Oceanography, La Jolla, Calif.

John T. Snow
Regents’ Professor of Meteorology, and
Dean Emeritus, College of Atmospheric and Geographic Sciences
University of Oklahoma, Norman

David W. Titley
Director, Center for Solutions to Weather and Climate Risk
Department of Meteorology,
Pennsylvania State University, University Park

Jennifer Wilcox
Assistant Professor of Energy Resources Engineering
Department of Energy, School of Earth Sciences, and Affiliate Faculty Member
Emmet Interdisciplinary Program for the Environment and Resources
Stanford University, Stanford, Calif.


Edward Dunlea, Study Director