Updated: October 2013
This is a writeup of a medium investigation, a brief look at an area that we use to decide how to prioritize further research.
In a nutshell
- What is the problem? Geoengineering – i.e., large-scale interventions in the climate to attempt to reduce global warming or its impacts – could conceptually mitigate some of the most catastrophic impacts of climate change, but major questions remain regarding the feasibility, likely costs and benefits, and optimal governance of the various possible geoengineering approaches.
- What are possible interventions? A philanthropist could directly fund research on these issues, lobby a government to fund research, or fund the development of governance mechanisms to enable research.
- Who else is working on it? Although there appears to be significant academic interest in geoengineering as a research area, funding appears to be limited. There appears to be much more funding on carbon dioxide removal than on solar radiation management; carbon dioxide removal is likely less risky than solar radiation management, but also likely more expensive and less fast-acting.
1. What is the problem?
Unmitigated climate change is likely to have large negative humanitarian impacts across a range of outcomes, and may have disastrous impacts. We have written about the likely impacts of unmitigated climate change here, summarizing the findings of the Intergovernmental Panel on Climate Change’s 2007 Fourth Assessment Report. We have also written about less likely but potentially extremely harmful impacts of more extreme climate changes on a separate page.
Once emitted, carbon continues to warm the planet for decades and a portion remains in the atmosphere (keeping temperatures warmer) for many centuries.1 In the event that existing efforts to limit carbon emissions fail to adequately reduce emissions, technology to rapidly limit temperature increases could be quite valuable, particularly in the event of worse-than-anticipated outcomes.
Geoengineering refers to large-scale interventions in the climate to attempt to reduce global warming or its impacts.2 We have seen two broad types of geoengineering discussed:
- Solar radiation management (SRM): reflecting back more sunlight to cool the earth without directly affecting carbon dioxide concentrations. The particular strategy we’ve seen discussed most frequently is injecting sulfate aerosols into the stratosphere to reflect back some sunlight, but other proposals include using saltwater spray to brighten clouds or using large mirrors in space to reflect back more sunlight.3
- Carbon dioxide removal (CDR): there are a number of technical proposals for attempts to remove carbon dioxide from the atmosphere that we have seen discussed, including direct air capture with chemical processes, biochar, ocean iron fertilization, and bio-energy with carbon capture and storage.4
Most of our research to date on geoengineering has focused on stratospheric injection of sulfate aerosols. Our understanding is that, relative to other geoengineering approaches, stratospheric injection is likely to be faster-acting and cheaper (in simple financial terms, not necessarily in terms of risks or costs and benefits), making it a plausible candidate for use in response to a climate emergency.5 On the other hand, our understanding is also that SRM has a greater potential for causing harm than CDR6 and that research into SRM is not as well-funded as research into CDR.7 We believe there to be many open questions about the potential effectiveness and side-effects of SRM, the answers to which could inform the behavior of policymakers facing climate emergencies.8
We have not done any systematic comparison of the case for funding further research on SRM compared to further research on CDR, and we have looked at only a subset of all possible SRM approaches, for instance, not thoroughly investigating albedo modification or marine cloud brightening. We regard these as important questions for further investigation should we proceed further with this research.
1.1 Background on stratospheric aerosol injection
Volcanic eruptions naturally produce aerosol that cools the planet by reflecting back sunlight. For example, the eruption of Mount Pinatubo in the Philippines in 1991 decreased the 1992 global mean temperature of the Earth by about 0.5ºC.9
These “natural experiments” raise the possibility of intentionally injecting sulfate aerosols into the stratosphere to offset the warming effects of climate change. Our understanding is that scientists believe it to be likely, though not certain, that such an effort would be feasible and would result in lower average global temperatures.10
Unlike many other approaches to climate change, such as emissions reductions or carbon dioxide removal, stratospheric injection of sulfate aerosols does not address the fundamental issue of elevated greenhouse gas concentrations. This means it would perform worse than other climate response strategies in many ways, including:
- Since it does not reduce carbon dioxide concentrations, sulfate aerosol injection would not address all of the results of high carbon emissions, such as ocean acidification.11
- Once started, rapidly halting aerosol injection would lead to far faster warming than climate change itself, with potentially more disruptive results.12
In addition, stratospheric aerosol also carries a variety of risks. For instance, some models have suggested that solar geoengineering could negatively affect precipitation, leading to droughts in some places.13 Some scholars have also pointed to the risk of conflict over control of geoengineering efforts as another potential negative outcome,14 and “unknown unknowns” are a central cause for concern.15
1.2 Open questions
Despite its potential benefit as a form of insurance against catastrophic climate emergencies, we believe that there remain many unanswered questions about whether and how stratospheric injection could or should be deployed, and what the likely positive and negative effects of deployment would be.
Some of the open questions we see as most important are:
- Could stratospheric aerosol injection offset several degrees of warming on an ongoing basis? Although volcanic eruptions serve as precedent for small levels of short-term cooling, some have argued that there are limits on how much cooling sulfate aerosols could produce,16 and, in any case, there is the possibility of other limitations on the viability of sulfate aerosols.
- What are the likely humanitarian costs of conducting such an effort, and are there technical strategies that could be used to mitigate them? One example that has been cited is the possibility that sulfur aerosol injection would reduce the strength of the Asian monsoon.17 Another possibility we’ve seen discussed is that sulfate aerosols would harm the ozone layer.18
- How should a global geoengineering scheme be governed? What would the political implications of the availability of sulfate aerosol injection technology be? International violence arising from disputes over the appropriate amount of aerosol injection to employ could conceivably be much more harmful than aerosol injection itself.19
Researching this topic could be very valuable no matter the findings. In the event that large-scale stratospheric aerosol injection could not feasibly reduce temperature, or that deploying it would cause more harm than benefit, having that knowledge prior to attempts to deploy the technology in an emergency situation could be enormously valuable. If large-scale stratospheric aerosol injection could feasibly reduce temperature, and would be net-beneficial under some future set of adverse climate conditions, that also seems to be quite valuable knowledge for policymakers to have. In either case, effective and informed governance could be invaluable.
2. What are possible interventions?
The two main strategies we see for using philanthropic funding to help address these questions are:
- directly funding further research
- advocating for governmental funding of further research.
In practice, either overarching approach could involve a focus on governance discussions and research, as opposed to a focus on directly attempting to answer the kinds of questions mentioned above. Governance of geoengineering research itself appears to be an active area of research.20
We are not aware of any non-profit organizations currently raising money to systematically pursue any of these aims, and we do not have a strong sense of what the likely costs or returns to these approaches would be.
3. Who else is working on this?
Our understanding is that there is a significant amount of academic interest in stratospheric aerosol injection, but that government and philanthropic funding for research is limited:
- A September 2010 report by the United States Government Accountability Office assessed U.S. federal funding for geoengineering research in fiscal years 2009 and 2010, reporting $949,000 of research on solar radiation management and about $101 million on geoengineering research overall, the vast majority of which was on conventional mitigation approaches that could be relevant to geoengineering.21
- During a May 2013 conversation, Andrew Parker estimated that the total sum of global government research spending on ongoing solar geoengineering research projects was roughly $20-25 million; since many of the projects span multiple years, the figure does not represent an annual estimate.22
- Bill Gates has personally funded $4.6 million worth of geoengineering research, including but not exclusively focused on stratospheric aerosol injection.23
Building on a list compiled by Andrew Parker and David Keith (PDF), we have tried to identify funded projects and funding sources around the world that explicitly include a significant solar geoengineering component (XLS).24 Our total tally of funding for such projects (for which we have funding information) amounts to about $11 million/year. This may be an overestimate of total resources directed to solar geoengineering, as it incorporates non-solar-geoengineering aspects of grants that are only partially devoted to solar geoengineering, but we believe it is more likely to be an underestimate of total resources because:
- research that is supported by general institutional resources (such as unrestricted funding to a university, graduate students stipends, or computing resources) is not accounted for
- some funded research that might be classified as solar goengineering may not be explicitly portrayed as such by the researchers or grant agencies
- our search strategy of explicitly enumerating all the grants that we know of and taking the sum of their funding means than any missed funding sources would entail an underestimate, and we believe that we missed at least some funding.25
For details of the projects included in our tally, see our spreadsheet on geoengineering research funding.
4. Questions for further investigation
Our research in this area has been relatively limited, and many important questions remain unanswered by our investigation. (These are meant to be distinct from the questions above, for which we believe further academic research is necessary. These questions are for our further research.)
Amongst other topics, further Open Philanthropy Project work on this cause might address:
- How would further research on sulfate aerosol injections compare with other research related to climate change, such as further monitoring of feedbacks, or with other types of geoengineering research, such as carbon dioxide removal or marine cloud brightening?
- How likely is it that funding research on geoengineering would cause harm (e.g. by undermining public support for optimal emissions reductions or by starting down a “slippery slope” towards deployment)? To what extent are policymakers considering geoengineering likely to respond to improved evidence?
- What type of research is likely to be most helpful for policymakers, and what is the best way to facilitate its creation? Should a philanthropist focus on directly supporting scientific research or on improving the governance of research, or both?
- How long is it likely to take to obtain the main benefits from a geoengineering research program? How likely are major funders to enter the field over that time horizon?
- What would the appropriate level of investment in a research program be, and how does this vary based on strategy (e.g. by whether a philanthropist directly funds research versus governance versus lobbying for more research)?
We believe that answering these questions would require a considerably deeper investigation than we have done to date.
5. Our process
We initially decided to investigate solar geoengineering as part of our more general shallow investigation of climate change as a potential philanthropic program area because we had heard about it in the popular press and because the Copenhagen Consensus report on climate change identifies geoengineering as a particularly promising mechanism for responding to the threat of climate change.26
Our initial investigation in mid-2012 consisted of reading a number of articles about geoengineering and speaking with several senior scholars who had written about the issue. We returned to have a few more conversations and to write up this review in the spring of 2013. Public notes are available from our conversations with:
- Michael MacCracken on May 18, 2012.
- Philip Rasch on May 22, 2012.
- Jane C.S. Long on June 1, 2012.
- Klaus Keller on April 18, 2013.
- Andy Parker on May 20, 2013.
We also attended a portion of the Fourth Interdisciplinary Summer School on Geoengineering at Harvard in August 2013, entitled “Solar Radiation Management: Exploring uncertainties and trade-offs.”
Our research has particularly but not exclusively focused on stratospheric injection of sulfate aerosols, one particular geoengineering approach, because we believe it may be worse-funded, relative to its potential importance, than other aspects of geoengineering research, but this is something we have not investigated deeply and regard as an important issue for further investigation.
|Blackstock et al. 2009||Source||Archive|
|Copenhagen Consensus on Climate: Findings of the Expert Panel||Source||Archive|
|IPCC AR4 WGI||Source||Archive|
|Moreno-Cruz and Keith 2012||Source||Archive|
|Rasch et al. 2008||Source||Archive|
|Ricke, Morgan, and Allen 2010||Source||Archive|
|Robock, Oman, and Stenchikov 2008||Source||Archive|
|Ross and Matthews 2009||Source||Archive|
|Solar Radiation Management Governance Initiative 2011||Source||Archive|
|Fund for Innovative Climate and Energy Research||Source||Archive|