Geoengineering proposals to deliberately alter the climate in response to the greenhouse effect have appeared in scientific advisory reports since at least the 1960s. Until recently, these proposals generally remained outside the mainstream discussions of climate policy, which focused either on strategies to reduce emissions or adapt to climate change impacts. However, there is growing concern among many scientists that the lack of progress on emissions reductions will lead to gradual increases in atmospheric concentrations of CO beyond a threshold that could prevent substantial impacts to human health and environmental systems. Furthermore, there is also concern about the existence of “tipping points,” where the earth’s climate system reaches a threshold that unexpectedly results in abrupt and severe changes. One example would be the rapid collapse of the West Antarctic Ice Sheet—which would lead to a large and sudden contribution to sea level rise. These concerns have led to increased interest in geoengineering as a potential tool to help reduce the impacts of climate change, although the NRC study noted that few, if any, individuals are promoting geoengineering as a near-term alternative to emissions reductions. While both CDR and SRM are intended to reduce global temperatures, there are substantial differences in how CDR and SRM operate on the climate system, the timescales required for results, and their associated risks and trade-offs. Consequently, CDR and SRM are often discussed separately. The Royal Society identified several CDR approaches that would directly remove CO in the ocean or on land. Examples of ocean-based CDR approaches include: Enhanced removal by physical processes. Enhanced upwelling/downwelling—altering ocean circulation patterns to bring deep, nutrient rich water to the ocean’s surface (upwelling), to promote phytoplankton growth—which removes CO-rich water from the surface of the ocean to the deep-sea (downwelling). Enhanced removal by biological processes. Ocean fertilization— introducing nutrients such as iron, phosphorus, or nitrogen to the ocean surface to promote phytoplankton growth. The phytoplankton remove CO is transported to the deep ocean as detritus. Enhanced removal by chemical processes. Ocean-based enhanced weathering— accelerating chemical reactions between certain minerals and CO to a nongaseous state. Methods include adding chemically reactive alkaline minerals, such as limestone or silicates, to the ocean to increase the ocean’s natural ability to absorb and store COExamples of land-based CDR approaches include: Physical removal by industrial processes. Direct air capture— technology-based processing of ambient air to remove CO from the atmosphere. The resulting stream of pure CO Biomass energy with CO capture and geological sequestration— harvesting vegetation and using it as a fuel source with capture and storage of the resulting emissions in geological formations (geological sequestration). Biomass for sequestration—harvesting of vegetation and sequestering it as organic material by burying trees or crop wastes, or as charcoal (biochar). Afforestation and land-use management—the planting of trees on lands that historically have not been forested, or otherwise managing vegetation cover to maximize CO, which convert the CO into a geological formation of reactive minerals. The Royal Society identified several SRM approaches that would reflect a small percentage of incoming sunlight back to space, as shown in figure 2. SRM approaches are generally discussed in terms of which sphere they would act upon—space, the atmosphere, or the earth’s surface. Examples of SRM approaches include: Space-based methods. Reflecting or deflecting incoming solar radiation using space-based shielding materials, such as mirrors. Atmosphere-based methods. Stratospheric aerosol injection—injecting reflective aerosol particles into the stratosphere to scatter sunlight back into space. Although it is possible that a wide range of particles could serve this purpose, most attention has been on sulfur particles—partly because temporary global cooling has been produced in the past by volcanic eruptions. Cloud-brightening—adding sea salt or other cloud condensation surfaces to low-level marine clouds to increase their ability to reflect sunlight before it reaches the earth’s surface. Surface-based methods. Increasing the reflectivity of the earth’s land or ocean surfaces through activities such as painting roofs white, planting more reflective crops or other vegetation, or covering desert or ocean surfaces with reflective materials. According to the NRC and Royal Society studies, geoengineering is one of several potential tools to limit the impact and consequences of climate change. However, these studies state that geoengineering is a potential complement to, rather than a substitute for, sharp reductions in greenhouse gas emissions. For example, while geoengineering includes a range of approaches with varying degrees of potential effectiveness and consequences—no geoengineering approach can provide an easy or risk- free alternative solution to the problem of climate change, according to the Royal Society study. For example, compared to current CDR proposals, using SRM to divert incoming sunlight would relatively quickly produce a cooling effect to counteract the warming influence of increased atmospheric concentrations of greenhouse gases. However, SRM does not address the rising atmospheric concentration of greenhouse gases produced by human activity, and therefore would not reduce other serious climate change impacts such as ocean acidification. Furthermore, according to these studies, both CDR and SRM involve additional environmental risks or other trade-offs. For example, ocean- based CDR approaches, such as ocean fertilization, could have unanticipated negative impacts on ocean ecosystems. Additionally, the large-scale deployment of certain land-based CDR approaches, such as afforestation, land-use management for sequestration, and biomass for energy or burial, create trade-offs for land use. In general, the Royal Society study found that compared to CDR, most SRM approaches are associated with a higher risk of negative environmental effects, such as negative impacts on regional temperature or precipitation. For example, one study found that combining a reduction of incoming solar radiation with high levels of atmospheric CO could have substantial impacts on regional precipitation—potentially leading to reductions that could create droughts in some areas. Additionally, the Royal Society study said that increasing the reflectivity of desert or ocean surfaces could have major impacts on desert or ocean ecosystems. Moreover, this study indicated that the artificial balance between increased greenhouse gas concentrations and reduced solar radiation created by large-scale deployment of an SRM approach would need to be maintained over decades and possibly centuries or longer. Experts said that geoengineering is an emerging field, with relatively few experiments or other studies conducted and with major uncertainties remaining. We found that more is known about certain CDR approaches, since related laboratory and field experiments have been conducted, whereas there is limited understanding of other CDR approaches and SRM. Moreover, major uncertainties remain regarding the scientific, legal, political, economic, and ethical implications of researching or deploying geoengineering. : Update and Recommendations (Paris: 2007). energy requirements, and scalability. Similarly, the Royal Society study found that both land- and ocean-based enhanced weathering CDR approaches could potentially store a large amount of carbon, but face barriers to deployment such as scale, cost, and possible environmental consequences. This report also found that while some other land-based CDR approaches—such as afforestation, land-use management techniques, and biomass for energy or burial—can remove CO on a global scale is low. Other CDR approaches have been the focus of relatively few laboratory and field experiments, and fundamental questions remain about their potential efficacy. For example, according to the Royal Society and NRC studies, while ocean fertilization has received some sustained research activity, its potential to remove CO For example, according to researchers who designed a 2009 joint German and Indian iron fertilization experiment, their experiment was designed to test a range of scientific hypotheses pertaining to the structure and functioning of Southern Ocean ecosystems and their potential impact on global cycles of biologically-generated elements, such as carbon and nitrogen. Furthermore, these researchers noted that future long-term experiments to study phytoplankton blooms and their effect on the deep ocean and underlying sediments would have to be much larger than experiments to date. According to our review of relevant studies and expert interviews, understanding of SRM is more limited than that of CDR because there have been few laboratory experiments, field experiments, or computer modeling efforts. Two of the most frequently discussed SRM approaches are stratospheric aerosol injection and cloud-brightening, according to many of the scientific experts we spoke with. For stratospheric aerosol injection, some of the experts said that research to date consisted primarily of a few modeling analyses. They also said that more work would need to be done to assess whether this approach could reduce incoming solar radiation without serious consequences. For example, one study identified the potential for regional impacts on precipitation— potentially leading to drought in some areas. Based on our literature review and interviews with experts, to date only one study has been published for a field experiment related to SRM technologies—a 2009 Russian experiment that injected aerosols into the middle troposphere to measure their reflectivity. Similarly, in the case of cloud-brightening, several experts said that there currently is not enough research to assess its effectiveness or impacts. According to the 2010 NRC study, other methods for SRM, including using space-based reflectors and increasing the solar reflectivity of buildings or plants, have limited potential, either due to the cost of deployment or the limited potential to affect the climate. Experts we interviewed and relevant studies identified several major uncertainties in the field of geoengineering that are in need of further investigation. These uncertainties ranged from important scientific questions for CDR and SRM, to political, ethical, and regulatory issues. Areas that merit further investigation include: Technical feasibility and effectiveness of SRM and certain CDR approaches. Experts we interviewed and the Royal Society and NRC studies agreed that SRM approaches generally were not researched sufficiently to be considered well-understood or technically feasible. Additionally, questions remain regarding the effectiveness of certain CDR approaches, such as ocean fertilization and some land-based methods, to significantly reduce atmospheric concentrations of CO on a global scale, or sequester CO The Royal Society study also noted that large-scale deployment of CDR approaches, such as methods requiring substantial mineral extraction—including land- or ocean-based enhanced weathering— may have unintended and significant impacts within and beyond national borders. For example, the study noted that impacts from enhanced weathering approaches could include localized environmental damage caused by increased mineral extraction activity, as well as changes to soil and ocean surface water pH that could affect vegetation and marine life. Several of the experts that we spoke with agreed that potential unintended consequences of geoengineering approaches require further study. Better understanding of the climate and a way to determine when a “climate emergency” is reached. The NRC study recommended additional basic climate science research, including (1) improved detection and attribution of climate change to distinguish the effects of intentional intervention in the climate system from other causes of climate change, and (2) information on climate system thresholds, reversibility, and abrupt changes to inform societal debate and decision-making over what would constitute a “climate emergency” and whether deployment of a geoengineering approach would be merited. How best to regulate geoengineering internationally. Several of the experts we interviewed as well as the NRC study emphasized the potential for international tension, distrust, or even conflict over geoengineering deployment. The NRC study also stated that global- scale geoengineering deployment creates the potential for uneven positive and negative regional outcomes, and this raises questions of decision-making and national security. Further research can help clarify what type of governance might be useful and when, both for deployment and for field experiments that may involve risks of negative consequences. Political, economic, and ethical concerns. Some experts we interviewed and relevant studies said that geoengineering introduces important political, economic, and ethical questions. For example, several experts said that pursuing geoengineering research could unintentionally reduce interest in reducing CO emissions and that social science research would be needed to assess this potential effect. The NRC studies stated that major questions remain regarding the economic viability of certain CDR approaches, such as direct air capture and enhanced weathering. Additionally, one expert raised concerns over the potential economic costs associated with unintended impacts from deploying SRM. Furthermore, NRC reported that public involvement is critical to making decisions about whether to pursue testing and deployment of geoengineering and that research is needed to determine how best to involve the public in such a decision-making process. USGCRP agencies reported funding at least 52 research activities relevant to geoengineering in fiscal years 2009 and 2010. We found that, of these 52 activities, 43 were either related to conventional mitigation strategies or were fundamental scientific research, whereas 9 directly investigated a particular geoengineering approach. We identified approximately $100.9 million in geoengineering-related funding across USGCRP agencies in fiscal years 2009 and 2010, with about $1.9 million of this amount related to research directly investigating a particular geoengineering approach. The other roughly $99 million was related to research concerning conventional mitigation strategies that could be applied directly to a particular geoengineering approach or basic science that could be applied generally to geoengineering. However, there is no coordinated federal strategy or operational definition for geoengineering, so agencies and policymakers may not know the full extent of relevant federal research. The 13 agencies participating in USGCRP identified 52 research activities relevant to geoengineering—accounting for approximately $100.9 million in federal funding for fiscal years 2009 and 2010. Twenty-eight of these activities—funded at approximately $54.4 million—were related to conventional mitigation strategies that are directly applicable to a particular CDR approach, such as enhancing land-based biological removal of CO, according to our analysis. Fifteen of the reported activities—funded at approximately $44.6 million—were fundamental scientific efforts that could be generally applied to geoengineering, such as modeling the interactions between the atmosphere and the climate and basic research into processes to separate gas streams into their individual components, such as CO Of the 43 activities related to fundamental research or mitigation efforts relevant to geoengineering but not designed to address it directly, the Department of Commerce (Commerce) reported the most funding— approximately $41.6 million. This was largely due to the National Oceanic and Atmospheric Administration’s (NOAA) climate modeling and monitoring of biological emissions and absorption of greenhouse gases, which NOAA officials said could be relevant for assessing the impacts and efficacy of various geoengineering approaches. The U.S. Department of Agriculture (USDA), DOE, the Department of the Interior (Interior), and EPA reported similar levels of funding—from about $11.3 million to $13.9 million. These efforts were largely directed at measuring and monitoring carbon sequestration potential in soils and biomass and assessing the impacts and storage potential for geological sequestration of CO. Although these activities are associated with efforts to reduce or offset emissions, agency officials identified them as relevant to certain CDR approaches—such as large-scale afforestation, and direct air capture—based on the working definition we provided. Table 2 summarizes the approximately $99 million in reported funding for the 43 relevant activities related to conventional mitigation efforts and fundamental scientific research, by agency. The National Science Foundation (NSF), DOE, and Commerce were the only agencies that reported funding for activities directly supporting geoengineering research during fiscal years 2009 and 2010. Of these agencies, NSF reported the most funding—approximately $1.1 million— directed to three research activities: a study on the potential impacts of ocean iron fertilization, a study to examine the moral challenges associated with SRM, and a modeling effort investigating stratospheric aerosol injection and space-based SRM approaches. DOE reported funding research—approximately $700,000—for two studies about direct air capture technologies, a modeling activity for stratospheric aerosol injection and cloud-brightening, as well as a study investigating the unintended consequences of climate change responses, including CDR and SRM approaches. Commerce reported funding two relevant research efforts—for about $70,000—examining the unintended impacts of SRM approaches, with one study focused on climate-related impacts and the other study exploring potential effects on solar electricity generation. Table 3 summarizes the approximately $1.9 million in reported funding for the nine relevant activities directly supporting geoengineering research, by agency. During our review, we also found examples of other relevant activities sponsored by USGCRP agencies that were outside the scope of our data request, mostly because they occurred prior to 2009. These activities included: DOE sponsored studies on ocean-based carbon sequestration approaches, such as ocean fertilization and direct injection of CO Additionally, scientists at NASA’s Ames Research Center held a conference on SRM approaches in 2006, in conjunction with the Carnegie Institution of Washington. NASA also funded atmospheric modeling studies, which were used by independent researchers, in part, to assess the potential impact of stratospheric aerosols on the ozone layer. In 2008, NSF sponsored studies examining the long-term carbon storage potential of soils and the impact of increased nitrogen on biological carbon sequestration. A Department of Defense (DOD) advisory group sponsored a 1-day workshop at Stanford University on geoengineering in 2009; however, DOD officials said that no funded research projects resulted from this workshop. In 2007, EPA funded research relevant to the economic implications of SRM approaches through its National Center for Environmental Economics. Furthermore, federal officials also noted that a large fraction of the existing federal research and observations on basic climate change and earth science could be relevant to improving understanding about proposed geoengineering approaches and their potential impacts. For instance, federal officials said that basic research conducted by USGCRP agencies into oceanic chemistry could help address uncertainty about the potential effectiveness and impacts of CDR approaches, such as ocean fertilization. Similarly, ongoing research conducted by USGCRP agencies related to understanding atmospheric circulation and aerosol/cloud interactions could help improve understanding about the potential effectiveness and impacts of proposed SRM approaches. We found that it was difficult to determine the full extent of federal geoengineering research activities because there is no coordinated federal strategy for geoengineering, including guidance on how to define federal geoengineering activities or efforts to identify and track federal funding related to geoengineering. Officials from federal offices coordinating federal responses to climate change—CEQ, OSTP, and USGCRP—stated that they do not currently have a coordinated geoengineering strategy or position. For example, a USGCRP official stated that there is no group coordinating federal geoengineering research and that such a group is not currently necessary because of the small amount of federal funding involved. However, while USGCRP agencies reported about $1.9 million in funding for activities directly investigating geoengineering, federal officials also told us that a large fraction of the existing federal research and observations on basic climate change and earth science could be relevant to understanding geoengineering. According to the USGCRP’s most recent report to Congress, USGCRP agencies requested roughly $2 billion in budget authority for climate change and earth science activities in fiscal year 2010. Consequently, the actual funding for research that could be applied either generally or directly to understanding geoengineering approaches is likely greater than the roughly $100.9 million reported in response to our data request. However, without the guidance of an operational definition for what constitutes geoengineering or a strategy to capitalize on existing research efforts, federal agencies may not recognize or be able to report the full extent of potentially relevant research activities. For example, some agency officials indicated that, without a clear governmentwide definition, in their determination of which federal research activities were relevant to geoengineering, our data request was subject to different interpretations— particularly for CDR approaches, since there is extensive overlap with existing mitigation efforts. In particular, EPA and USDA officials said that there is a large body of research regarding biological sequestration but that these officials would not consider it to be geoengineering. However, officials from other agencies, such as Interior and DOE, included certain research on biological sequestration as relevant to geoengineering based on the definition we provided. Similarly, we found that from NSF officials’ perspectives, the distinction between existing efforts to develop carbon capture and storage technologies, such as membranes to separate CO from other gases, and geoengineering direct air capture technologies is also not well-defined. This definitional issue is not unique to these agencies. In its recent study Advancing the Science of Climate Change, NRC acknowledged the lack of consensus regarding what constitutes geoengineering in relation to widely accepted practices that remove CO The NRC study included other findings about the nation’s climate change science efforts that may be relevant to a potential federal geoengineering strategy. The study emphasized the importance of providing decision makers with scientific information on a range of available options, including geoengineering, to limit future climate change and its impacts. According to this study, this information would help policymakers use adaptive risk management to update response strategies as new information on climate change risks and response strategies becomes available. NRC recommended an integrative, interdisciplinary research effort to improve understanding of available response options, as well as of climate change and its impacts. The study indicated that this effort should be led by a single coordinating body, and NRC identified USGCRP’s capacity to play a role in such an effort. Similarly, several of the experts we interviewed recommended that federal geoengineering research should be an interdisciplinary effort across multiple agencies and led by a coordinating body, such as OSTP or USGCRP. Our recent work offers insights on key considerations for establishing governmentwide strategies, which could be relevant to a future geoengineering strategy. Specifically, our review of federal efforts related to crosscutting issues, such as climate change adaptation and global food security, highlighted key practices for enhancing collaboration across agencies. These practices include establishing a commonly accepted operational definition for relevant activities; leveraging existing resources to support common outcomes and address identified needs; and developing mechanisms to monitor, evaluate, and report on results. Furthermore, our review of DOE’s FutureGen project—a program to help build the world’s first coal-fired, zero-emissions power plant—identified important factors to consider when developing a strategy for technology- based research. Specifically, we found that it is important to comprehensively assess the costs, benefits, and risks of each technological option and to identify potential overlap between proposed and existing programs. For example, the NRC study acknowledged the importance of improving understanding of SRM and its consequences, without replacing or reducing existing research on climate change science or other approaches to limiting climate change or adapting to its impacts. As the study noted, much of the research needed to advance scientific understanding of SRM, such as studying the climate effects of aerosols and cloud physics, is also necessary to advance understanding of the climate system, and could therefore contribute more broadly to climate change science. Similarly, an OSTP official said that ongoing fundamental research to investigate the relationship of cloud/aerosol interactions could also be applied to improve understanding of certain SRM approaches. In the absence of a coordinated federal strategy for geoengineering, decisions about whether a particular research activity is relevant to geoengineering may not necessarily be consistent across the federal government. In addition, agencies generally do not collect and share information on such research activities in the context of geoengineering. While EPA officials told us that certain agencies, such as EPA, State, and NOAA, share information about ocean fertilization and direct injection of CO into deep sub-seabed geological formations as part of a working group for international regulation of the ocean, a USGCRP official said there is no working group to share information or coordinate geoengineering research more broadly, because such an action would require a decision from the administration to pursue geoengineering research on a larger scale. However, without a coordinated effort to identify relevant research and share information across agencies, policymakers and agency officials may lack key information needed to inform their decisions on geoengineering research. For example, if policymakers and officials do not know the full extent of the relevant federally funded research that is under way, they may not have sufficient information to leverage existing research on climate change science to also improve understanding of geoengineering. Legal experts we interviewed and EPA and Department of State (State) officials said that the extent to which existing laws and international agreements apply to geoengineering is unclear, largely because detailed information on geoengineering approaches and effects is not available. EPA has taken steps to regulate one CDR approach and has determined that an existing law provides sufficient authority to regulate two other approaches. EPA officials provided their preliminary thoughts on how other laws might apply to geoengineering activities. However, according to EPA officials, they have not fully assessed (1) whether the agency has the authority to regulate or (2) how to regulate most geoengineering approaches, because the research is still in its initial stages. Similarly, legal experts and State officials stated that many international agreements could apply to geoengineering; however, most agreements’ applicability is unclear because they were not intended to address geoengineering and parties to the agreements have not determined whether or how the agreements should apply to relevant geoengineering activities. This uncertainty and inaction is due, in part, to the limited general understanding of geoengineering and a lack of geoengineering activity. Legal experts and federal officials identified challenges for establishing governance of geoengineering, such as the potential for unintended and uneven impacts, although their views differed on the most effective governance approach. EPA officials stated that the extent to which existing federal environmental laws apply to geoengineering is unclear, largely because detailed information on most geoengineering approaches and effects is not available. However, EPA officials said that there is relatively more information available about geological sequestration of CO from the air and sequester it underground or in the sub-seabed. EPA has taken steps to regulate geological sequestration under the Safe Drinking Water Act, and EPA officials said that the Marine Protection, Research, and Sanctuaries Act of 1972 provides the agency with authority to regulate (1) certain sub-seabed geological sequestration activities, and (2) ocean fertilization activities. Specifically: EPA has authority under the Safe Drinking Water Act to regulate underground injections of various substances and is using this authority to develop a rule to govern the underground injection of CO captured from an emission source, such as a power plant or industrial facility, the rule’s definition of geological sequestration is broad enough to include long-term sequestration of CO injection and geological sequestration, which is scheduled to be finalized in the fall of 2010. Under the Marine Protection, Research and Sanctuaries Act of 1972, as amended, certain persons are generally prohibited from dumping material, including material for ocean fertilization, into the ocean without a permit from EPA. EPA officials said that certain sub-seabed geological sequestration of CO Resource Conservation and Recovery Act of 1976 (RCRA). RCRA regulates the management of hazardous waste from generation of the waste to its disposal. An EPA official stated that EPA has been examining questions of RCRA’s applicability to geological sequestration of CO and is currently considering a proposed rule to clarify how RCRA hazardous waste requirements apply in that context. This official also noted that RCRA’s applicability to other geoengineering approaches where materials are applied to the land or oceans would depend on whether there was intent to discard the materials and whether the materials are a hazardous waste. Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA). CERCLA authorizes EPA to clean up hazardous substance releases at contaminated sites and then seek reimbursement from the parties responsible for contaminating them or compel the responsible parties to clean up these sites. Responsible parties include current and former site owners and operators, as well as those who transport or arrange for the disposal of the hazardous substances. Although a stream of pure CO streams could contain hazardous substances, thus subjecting the parties injecting the CO enters groundwater, it might also cause hazardous substances, such as some metals, to be dissolved by the groundwater from enclosing strata. If that constitutes a release of hazardous substances from a “facility,” such as the strata, then the owner of that facility could be liable for any cleanup costs caused by that release. This official was not aware of CERCLA’s applicability to any other geoengineering activity. Clean Air Act. This law authorizes EPA to regulate emissions of certain air pollutants from mobile and stationary sources into the ambient air, including those that destroy the stratospheric ozone layer. EPA officials said that the act could apply to geoengineering activities that emitted air pollutants into the atmosphere—either as the purpose of the activity or as a side effect—depending on where the pollutant was released and the delivery mechanism. Officials also noted that although the act regulates emissions into the ambient air, substances injected into the upper atmosphere that eventually cycle down to ground level could also be subject to regulation, depending on the definition of ambient air. EPA officials stated that they would require further information on the specific technology and activity to determine exactly how the law might apply. In addition, EPA and DOE officials noted that geoengineering activities undertaken, funded, or authorized by federal agencies would be subject to the National Environmental Policy Act of 1969 (NEPA), the Endangered Species Act, and the conformity provision of the Clean Air Act. NEPA requires federal agencies to evaluate the likely environmental effects of certain major federal actions using an environmental assessment or, if the projects likely would significantly affect the environment, a more detailed environmental impact statement. Under the Endangered Species Act, geoengineering activities taken or authorized by federal agencies would require consultation among federal agencies, including the Fish and Wildlife Service and NOAA, to ensure that the activity is not likely to jeopardize the continued existence of any endangered or threatened species or adversely modify habitat critical for the species. Under the Clean Air Act’s conformity provision, no federal agency may approve or provide financial assistance for any activity that does not conform with a state implementation plan, which is a plan required by the act to ensure that national ambient air quality standards are met. Acknowledging the lack of an existing international agreement that comprehensively addresses geoengineering, State officials and legal experts we interviewed said that many agreements could perhaps apply to a geoengineering activity and its impacts, depending on the activity’s nature, location, and actors. For example, some international agreements with broad scopes, such as the United Nations Framework Convention on Climate Change, could apply generally to geoengineering activities, whereas other agreements specifically addressing the atmosphere, oceans, and space could apply only if the activity occurred in or impacted that particular area. However, international agreements legally bind only those countries that have become parties to the particular agreement. Therefore, the number of parties to a particular agreement determines, in part, where the agreement applies, and countries that are not parties are not legally bound to abide by the agreement. Table 4 summarizes certain agreements identified by legal experts and relevant studies as potentially applicable to geoengineering and the number of parties to a particular agreement. Almost all the legal experts and State officials we spoke with noted that, of all the potential geoengineering approaches, sub-seabed geological sequestration of CO Ocean fertilization. The parties to the London Convention and the London Protocol have decided that the scope of these agreements includes ocean fertilization activities for legitimate scientific research and that ocean fertilization activity other than legitimate scientific research should be considered contrary to the aims of the agreements and should not be allowed. The treaties’ scientific bodies are developing an assessment framework for countries to use in evaluating whether research proposals are legitimate scientific research. Additionally, the parties to the Convention on Biological Diversity issued a decision in 2009 urging countries to ensure that ocean fertilization activities, except for certain small-scale scientific research within coastal waters, do not take place until there is an adequate scientific basis on which to justify them and a global, transparent, and effective control and regulatory mechanism in place. The parties to the London Convention and London Protocol are considering an additional resolution or amendment concerning ocean fertilization, and the parties to the Convention on Biological Diversity continue to discuss the issue. Geological sequestration. In 2006, the parties to the London Protocol agreed to amend the protocol to include, in certain circumstances, CO streams for sequestration in sub-seabed geological formations in the protocol’s list of wastes and other matter that could be dumped. Under the amendment, CO stream consists overwhelmingly of CO(3) no wastes or other matter are added for the purpose of disposing of those wastes or other matter. The parties also developed specific guidelines for countries to use when assessing whether applications for disposal of streams into sub-seabed geological formations is consistent with the protocol. In late 2009, the parties to the London Protocol adopted an amendment to allow the export of CO streams for disposal in certain circumstances. The parties are developing specific guidance for these exports and issues related to the management of transboundary movement of CO sequestration in sub-seabed geological formations. However, legal experts and State officials stated that although parties to three agreements have taken action to clarify the agreements’ applicability to particular geoengineering approaches, most agreements’ applicability is unclear because they were not intended to address geoengineering and the parties had not yet addressed the issue. In addition, legal experts and federal officials generally said that more detailed information on geoengineering approaches and their effects would be needed for officials to develop a regulatory and governance framework. For example, aside from ocean fertilization and other marine-focused geoengineering approaches, State officials said that many of the ideas remain too theoretical and distant from implementation to consider addressing them through international law. Legal experts and EPA and State officials identified various challenges to establishing domestic and international governance of geoengineering. For example, the legal experts and EPA and State officials we interviewed generally agreed that there needs to be further research on most geoengineering approaches and their potential effects to inform—and in federal officials’ views to warrant—discussions regarding regulation. Similarly, some of these experts and federal officials said that a general lack of significant efforts to pursue geoengineering is a contributing factor to why geoengineering governance has not been pursued further to date. For example, a State official noted that geoengineering has not received much attention within international negotiations related to climate change, and there isn’t enough geoengineering-related activity to drive interest in expanding international governance at this time. Legal experts and State officials had differing views about an international governance framework for geoengineering. Specifically, several legal experts recommended including all geoengineering activities with transboundary impacts in a single comprehensive agreement. Some of these experts said an existing comprehensive international agreement could be adapted to address geoengineering. Some of them specifically identified the United Nations Framework Convention on Climate Change as an appropriate agreement because it addresses climate change and geoengineering is intended to diminish climate change or its impacts. Other legal experts said a new international agreement was needed because of the difficulty reaching consensus within the United Nations Framework Convention on Climate Change. Experts in favor of a single comprehensive agreement said that it would be preferable to the patchwork of existing agreements, which were not designed to address geoengineering, because these agreements do not create comprehensive governance frameworks that could be used to address geoengineering. Additionally, some experts said that certain existing agreements rely on the parties to regulate activities under their jurisdiction without the international community’s participation in decision-making, which may not be the best structure for regulating geoengineering research or deployment. State officials we interviewed said that it would be better to rely on existing treaties to the extent they are adequate and appropriate and consider developing new international instruments if needed, since there is limited knowledge and practice of geoengineering. State officials said this approach would enable greater rigor and flexibility than trying to address all geoengineering activities within a single comprehensive agreement. They cited the London Convention and London Protocol as examples. While these agreements might not have addressed ocean fertilization several years ago, the parties took action when ocean fertilization reached a state of development where an agreed approach to regulation was considered necessary, and the agreements now unquestionably address it. In contrast, State officials said that parties to other agreements have not addressed other geoengineering approaches because they have not reached a similar stage of development. State officials said it was hard to imagine a single agreement appropriately covering geoengineering activities with all potential transboundary effects. State officials also said that while some countries have called for a broader inquiry into marine geoengineering more generally under the London Convention and the London Protocol, the parties deemed those calls premature at best. Legal experts and EPA officials we interviewed generally agreed that the federal government should take a coordinated, interagency approach to domestic geoengineering regulation. For example, the legal experts who spoke about domestic regulation generally agreed that the federal government should play a role in governing geoengineering research— either by developing research norms and guidelines or applying existing regulations and guidelines. One expert noted that it was important that regulators stay abreast of research on the most mature technologies so that the regulatory framework would be in place prior to field experiments. Some experts and EPA officials also agreed that because there is a wide variety of geoengineering activities, research and regulation would fall under multiple agencies’ purview and expertise. For example, one expert said that there should be a coordinated interagency effort led by OSTP or USGCRP. Another said that the federal government should focus on a comprehensive policy for climate change, including geoengineering, and that that policy would determine what new regulations would be necessary to guide and govern research. EPA and State officials both said that agencies such as NOAA, NASA, and DOE should be involved in regulatory discussions due to their jurisdictional or scientific expertise. As an example, EPA officials noted that the Interagency Task Force on Carbon Capture and Storage, co-chaired by DOE and EPA, was created to propose a plan to overcome the barriers to widespread deployment of these technologies, which include geologic sequestration. The plan addresses, among other issues, how to coordinate existing administrative authorities and programs, legal barriers to deployment, and identifies areas where additional statutory authority may be necessary. Legal experts we interviewed generally agreed that governance for geoengineering research should be addressed separately from governance for deployment of geoengineering approaches. For example, experts said that discussions of governance of deployment were premature, and one expert cautioned that discussing deployment could raise the level of controversy surrounding the subject, leading to a general gridlock that could disrupt discussions about research and lower interest in a coordinated and transparent approach. Both State and EPA officials cited the need for further research into geoengineering prior to engaging in discussions of domestic regulation or a governance framework at the international level. State officials said that, in practice, the United States and other countries have already effectively separated geoengineering research and deployment governance for ocean fertilization under the London Convention and London Protocol, because the parties decided that any ocean fertilization activities other than those for legitimate scientific research should not be allowed at this time. However, the legal experts we spoke with also agreed that some type of regulation of geoengineering field research was necessary in the near future, particularly for those approaches where large-scale experiments could have transboundary impacts. According to these experts, any framework governing research should include several elements, such as transparency, coordination, flexibility, a review process for experiments, the use of environmental risk thresholds, and an emphasis on modeling prior to field studies. A few legal experts said that these elements could start as voluntary norms and guidelines within the research community and then evolve into formal regulations prior to field trials. As one expert said, transparent decision-making and guidelines are necessary to ensure that research does not pose unacceptable risk to the environment. State officials said that, generally, the United States supports careful consideration of research implications rather than a full ban on research. In addition, they said that some geoengineering research could be fostered most effectively through international cooperation and coordination rather than governance, or that domestic regulation is more appropriate than international regulation. Legal experts and EPA and State officials cited other challenges related to geoengineering governance, particularly for those approaches with uneven or unintended environmental effects. For example, some legal experts said that controversy surrounding certain geoengineering approaches, as well as a lack of understanding and acceptance, could make domestic and international governance difficult. In addition, State officials said that if large-scale experiments or activities have unknown consequences or effects borne by nations other than the nation conducting the experiment or activity, this could risk undermining existing agreements on climate change strategies. Furthermore, legal experts and EPA officials agreed that liability for unintended consequences was an important issue that would need to be addressed. Specifically, one expert suggested that there should be a mechanism to compensate individuals or nations for damages resulting from geoengineering activities. Moreover, some legal experts were concerned about the ability of parties to enforce certain international agreements related to geoengineering. Major scientific bodies such as the NRC and Royal Society have identified geoengineering as one of several potential tools to limit the impact and consequences of climate change. However, these bodies have stated that geoengineering is a potential complement to, rather than a substitute for, sharp reductions in greenhouse gas emissions. While the NRC and Royal Society have identified geoengineering as a potential tool, what role geoengineering might play in a domestic and international response strategy will likely be shaped by resolving unanswered scientific questions surrounding the technical feasibility, unintended consequences, effectiveness, cost, and risks associated with each approach. Answers to these questions will also inform the public debate concerning whether geoengineering is an acceptable response given the ethical and social implications of deliberate interventions in the earth’s climate system. The federal government is already engaging in research that could help address some of the uncertainties surrounding geoengineering and inform policy decisions about research priorities. While agencies identified about $100.9 million in research funding relevant to geoengineering in fiscal years 2009 and 2010, federal officials also said that a substantial portion of the existing federal climate change and earth science research could be relevant to understanding geoengineering—roughly $2 billion in requested budget authority for 2010 alone. However, because there is no coordinated federal geoengineering strategy, it is difficult to determine the extent of relevant research. At present, while some agencies are sharing information on two geoengineering approaches to inform negotiations relevant to international regulation of ocean dumping and address barriers to geological sequestration as a mitigation strategy, agencies generally are not collecting and sharing information more broadly on research relevant to other geoengineering approaches. Without a definition of geoengineering for agencies to use, and without coordination among agencies to identify the full extent of available research efforts relevant to geoengineering as well as to identify research priorities, policymakers and agency officials may lack sufficient information to leverage existing research resources to their full benefit. In turn, this lack of information may hinder policy decisions and governance at the domestic and international level. Even if policymakers decide that geoengineering should not be pursued domestically, knowledge of geoengineering approaches and their potential effects will be essential to inform international negotiations regarding other countries’ consideration of, or actions related to, geoengineering research and deployment. GAO recommends that the appropriate entities within the Executive Office of the President (EOP), such as the Office of Science and Technology Policy (OSTP), in consultation with relevant federal agencies, develop a clear, defined, and coordinated approach to geoengineering research in the context of a federal strategy to address climate change that (1) defines geoengineering for federal agencies; (2) leverages existing resources by having federal agencies collect information and coordinate federal research related to geoengineering in a transparent manner; and if the administration decides to establish a formal geoengineering research program, (3) sets clear research priorities to inform decision-making and future governance efforts. We provided a draft of this report to the Office of Science and Technology Policy (OSTP) within the Executive Office of the President (EOP) for review and comment. OSTP also circulated the report to the 13 participating USGCRP agencies. In response to the draft, OSTP, the Council on Environmental Quality, U.S. Department of Agriculture (USDA), Department of State (State), National Oceanic and Atmospheric Administration (NOAA), and National Science Foundation (NSF) neither agreed nor disagreed with our findings and recommendation; rather, they provided technical and other comments, which we incorporated as appropriate. General comments and our response are summarized below. In their comments, USDA, NSF, and OSTP raised various concerns about how geoengineering should be defined. For example, OSTP and USDA cited concerns that the definition used in this report is too broad because it overlaps with certain land-based practices, such as biological sequestration of CO emissions. For the purposes of this report, we used the Royal Society study’s definition and descriptions of geoengineering approaches because this study was the most comprehensive review of geoengineering science available at the time of our request. Other scientific organizations, such as the National Research Council (NRC), the American Meteorological Society, and the American Geophysical Union have also either reported on or issued position statements regarding geoengineering, and used a similarly broad definition. However, as we note in the report, discussions about how to define geoengineering and what activities should be considered geoengineering remain active. Variations in agencies’ interpretation of our data request, as well as the comments noted above, support our recommendation that additional clarity and guidance regarding the federal approach to geoengineering is needed, and that further discussion of what types of activities should be included in a federal operational definition of geoengineering may be warranted. Accordingly, we recommended that the appropriate entities within the EOP consult with the relevant federal agencies to develop a clear, defined, and coordinated approach to geoengineering research in the context of a federal strategy to address climate change. Additionally, NOAA and NSF noted that because the global nature of climate change requires an international response, international coordination and collaboration would be important for geoengineering activities and oversight efforts. As we noted in our report, the applicability of international agreements to geoengineering remains unclear; however, parties to three agreements have issued decisions regarding the agreements’ applicability to ocean fertilization and sub-seabed geological sequestration. Furthermore, the legal experts we spoke with generally agreed that some type of regulation of geoengineering field research is necessary in the near future, particularly for those approaches where large-scale experiments could have transboundary impacts. According to these experts, any framework governing research should include several elements, such as transparency, coordination, flexibility, a review process for experiments, the use of environmental risk thresholds, and an emphasis on modeling prior to field studies. NOAA emphasized the importance of fully understanding unintended consequences and risks associated with geoengineering approaches. In particular, NOAA commented that sufficient resources should be directed specifically towards identifying possible unintended consequences and risks. As we note in the report, relevant studies indicate that there are additional environmental risks and trade-offs associated with both CDR and SRM approaches. Furthermore, our discussions with experts and review of relevant studies identified unintended consequences associated with geoengineering approaches as a key uncertainty requiring further study. In addition to these comments, CEQ, OSTP, and the agencies provided technical changes and corrections which we incorporated where appropriate. As agreed with your office, unless you publicly announce the contents of this report earlier, we plan no further distribution until 30 days from the report date. At that time, we will send copies of this report to the appropriate congressional committees, the Office of Science and Technology Policy within the Executive Office of the President, and other interested parties. In addition, the report will be available at no charge on GAO’s Web site at http://www.gao.gov. If you or your staff members have any questions about this report, please contact Frank Rusco at (202) 512-3841 or ruscof@gao.gov, or John Stephenson at (202) 512-3841 or stephensonj@gao.gov. Contact points for our Offices of Congressional Relations and Public Affairs may be found on the last page of this report. GAO staff who made key contributions to this report are listed in Appendix V. This report examines (1) the general state of the science regarding geoengineering approaches and their potential effects; (2) the extent to which the federal government is sponsoring or participating in geoengineering research or deployment; and (3) the views of legal experts and federal officials about the extent to which federal laws and international agreements apply to geoengineering activities, and associated challenges, if any, to geoengineering governance. To determine the general state of the science regarding geoengineering approaches and their potential effects, we summarized the results of semi- structured interviews with scientific and policy experts as well as the findings from relevant literature. First, we identified 95 potential experts based on five criteria indicating recognition from their peers as geoengineering experts. These criteria included having (1) presented at the Asilomar International Conference on Climate Intervention Technologies, (2) presented at the geoengineering panels held at the American Association for the Advancement of Science 2010 Annual Meeting, (3) served as a witness at one of the three hearings on geoengineering held by the House Science and Technology Committee, (4) recommendations from other recognized experts that we had interviewed during our work for the March testimony for the committee, and (5) participating in smaller panels or working groups that specifically focused on geoengineering. To identify the most active experts in the field, we scored the experts from the initial list based on their participation in the five previously noted activities. Based on this process, we selected the 10 highest-scoring experts and contacted them for interviews. We selected 10 experts to ensure we could collect a range of views from experts associated with academia, nongovernmental organizations, and government. To assess potential conflicts of interest, we asked the 10 experts to submit a conflict of interest form. These forms included questions about potential financial or other interests that might bias an expert’s opinions related to the state of geoengineering science. We conducted a content analysis to summarize expert responses and grouped responses into overall themes. The views expressed by experts do not necessarily represent the views of GAO. Not all of the experts provided their views on all issues. In addition to gathering expert views, we selected and reviewed collaborative peer-reviewed studies that addressed geoengineering, such as the National Research Council’s Advancing the Science of Climate Change study as well as the Royal Society’s study Geoengineering and the climate: Science, governance and uncertainty. The Royal Society is the United Kingdom’s national academy of sciences. provided. We then categorized the remaining activities into three broad types: (1) activities related to conventional carbon mitigation efforts that are directly applicable to a proposed geoengineering approach, although not designated as such; (2) activities related to improving basic scientific understanding of earth systems, processes, or technologies that could be applied generally to geoengineering; and (3) activities designed specifically to address a proposed geoengineering approach that does not overlap with a conventional carbon mitigation strategy. We sent the results of our analysis and categorization of agency-reported activities to each agency for their review and verification in July 2010. Specifically, we asked agency officials to ensure that the data were complete and accurate, and that our categorization of the data was appropriate. Each agency verified our analysis. In addition, we met with officials and staff from interagency bodies coordinating federal responses to climate change, including the Office of Science and Technology Policy (OSTP), Council on Environmental Quality (CEQ), and USGCRP, as well as the Department of Energy (DOE), which coordinates the Climate Change Technology Program—a multiagency research and development program for climate change technology. We assessed the reliability of the data and found the data to be sufficiently reliable for the purposes of this report. , (5) water desalinization project using solar energy, (6) internationally collaborating with China to foster emissions mitigation research, (7) developing technology to facilitate the conversion of methane gas to liquid fuel, and five activities to develop technologies related to biofuels. Based on their description, we determined that these 12 activities did not appear relevant to identified CDR or SRM approaches. each expert from the initial list based on the three criteria noted above. Based on this process, we selected the 8 highest scoring experts and contacted them for interviews. We selected 8 experts because the scoring process created a natural break between the 8 highest scoring experts and the remaining experts. To assess potential conflicts of interest, we asked each expert to submit a conflict of interest form. These forms included questions about potential financial or other interests that might bias an expert’s opinions related to the applicability of federal laws and international agreements to geoengineering. We conducted a content analysis to summarize expert responses and grouped responses into overall themes. The views expressed by experts do not necessarily represent the views of GAO. Not all of the experts provided their views on all issues. We also met with federal officials from the Environmental Protection Agency (EPA) and the Department of State (State) to collect their views on the applicability of domestic laws and international agreements to geoengineering, and governance challenges, if any. In addition to gathering experts’ and federal officials’ views, we selected and reviewed collaborative reports that addressed geoengineering governance, such as the Royal Society’s study Geoengineering and the climate: Science, governance and uncertainty, and the United Kingdom House of Commons Science and Technology Committee report The Regulation of Geoengineering, among others. To corroborate the legal information provided to us by our experts, we utilized these collaborative reports as well as select articles from relevant journals to support specific key details from the interviews. We conducted this performance audit from December 2009 through September 2010 in accordance with generally accepted government auditing standards. Those standards require that we plan and perform the audit to obtain sufficient, appropriate evidence to provide a reasonable basis for our findings and conclusions based on our audit objectives. We believe that the evidence obtained provides a reasonable basis for our findings and conclusions based on our audit objectives. We identified and selected scientific and policy experts to provide their views on the general state of the science regarding geoengineering approaches and their potential effects. We also identified and selected legal experts to provide their views on the applicability of federal laws and international agreements to geoengineering, and associated challenges, if any, to geoengineering governance. This appendix lists the experts we selected and contacted for interviews. In two cases, experts we contacted did not participate in our review, either due to schedule conflicts or because they did not respond to our request. To help federal officials identify relevant activities, we provided them with a data collection instrument that defined geoengineering and described proposed geoengineering approaches, as outlined below. The definition and descriptions were based on the Royal Society study—which was the most authoritative review of geoengineering at the time of our data request. This appendix reflects the language and more technical descriptions we provided to the agencies and, as such, will not be an exact match to the more generalized language used to describe these approaches in the background section of this report. We have provided additional explanations of some scientific terms in footnotes to the text. These footnotes were not part of the data collection instrument sent to the agencies. Cloud condensation nuclei are small particles in the air that become surfaces on which water vapor can condense and form cloud droplets. Sources of cloud condensation nuclei can be both natural and human-caused. Natural sources of cloud condensation nuclei include volcanic dust, sea spray salt, and bacteria. Humans also release unnatural chemicals into the air from the burning of fossil fuels and from industrial sources. In response to our data collection instrument, the 13 agencies participating in the USGCRP reported the following research activities relevant to geoengineering. Our request was limited to activities funded during fiscal years 2009 and 2010; however, in some cases, reported activities were initiated prior to fiscal year 2009 and continued beyond fiscal year 2010, as noted in the “Dates of research” column in tables 5, 6, and 7. To be consistent with the tables in the report, the activities are organized by agency and geoengineering approach. According to agency officials, none of the activities listed below received funding in the American Recovery and Reinvestment Act of 2009. The Departments of Health and Human Services and State, as well as the U.S. Agency for International Development, the National Aeronautics and Space Administration, and the Smithsonian Institution, all reported no relevant activities during fiscal years 2009 and 2010. In addition to the contacts named above, Tim Minelli (Assistant Director), Ana Ivelisse Aviles, Judith Droitcour, Lorraine Ettaro, Cindy Gilbert, Eli Lewine, Madhav Panwar, Timothy Persons, Katherine Raheb, Benjamin Shouse, Jeanette Soares, Ardith Spence, Kiki Theodoropoulos, J. D. Thompson, and Lisa Van Arsdale made key contributions to this report.

Summary: Policymakers have raised questions about geoengineering--large-scale deliberate interventions in the earth's climate system to diminish climate change or its impacts--and its role in a broader strategy of mitigating and adapting to climate change. Most geoengineering proposals fall into two categories: carbon dioxide removal (CDR), which would remove carbon dioxide (CO2) from the atmosphere, and solar radiation management (SRM), which would offset temperature increases by reflecting sunlight back into space. GAO was asked to examine (1) the state of geoengineering science, (2) federal involvement in geoengineering, and (3) the views of experts and federal officials about the extent to which federal laws and international agreements apply to geoengineering, and any governance challenges. GAO examined relevant scientific and policy studies, relevant domestic laws and international agreements, analyzed agency data describing relevant research for fiscal years 2009 and 2010, and interviewed federal officials and selected recognized experts in the field. Few geoengineering experiments or modeling studies have been conducted, and major uncertainties remain on the efficacy and potential consequences of geoengineering approaches. GAO's review of relevant studies and discussions with selected experts indicated that relatively more laboratory and field research relevant to certain CDR approaches exists, although most of this research was not designed to apply to geoengineering. In contrast, few modeling studies or field experiments have focused on SRM approaches, according to experts and recent studies. Experts identified only one SRM field experiment with published results--a 2009 Russian experiment that injected aerosols into the middle troposphere to measure their reflectivity. Experts, as well as relevant studies, identified several major uncertainties in need of further investigation for CDR and SRM. Federal agencies identified 52 research activities, totaling about $100.9 million, relevant to geoengineering during fiscal years 2009 and 2010. GAO's analysis found that 43 activities, totaling about $99 million, focused either on mitigation strategies or basic science. Most of the research focused on mitigation efforts, such as geological sequestration of CO2, which were identified as relevant to CDR approaches but not designed to address them directly. GAO found that nine activities, totaling about $1.9 million, directly investigated SRM or less conventional CDR approaches. Officials from interagency bodies coordinating federal responses to climate change indicated that their offices have not developed a coordinated strategy, and believe that, due to limited federal investment, it is premature to coordinate geoengineering activities. However, federal officials also noted that a large share of existing federal climate science research could be relevant to geoengineering. Agencies requested roughly $2 billion for such activities in fiscal year 2010. Without a coordinated federal strategy for geoengineering, it is difficult for agencies to determine the extent of relevant research, and policymakers may lack key information to inform subsequent decisions on geoengineering and existing climate science efforts. According to legal experts and federal officials, the extent to which federal laws and international agreements apply to geoengineering is unclear. The Environmental Protection Agency (EPA) has taken steps to regulate one CDR approach and has determined that it has sufficient authority to regulate two other approaches. EPA officials said EPA has not assessed the applicability of other laws because geoengineering research is in its initial stages. Similarly, legal experts and Department of State officials said that, except for three instances, parties to international agreements have not addressed their agreements' applicability to geoengineering, largely due to limited geoengineering activity and awareness of the issue. Legal experts' and officials' views differed on the best approach for international governance, but generally agreed that the federal government should take a coordinated, interagency approach on domestic regulation. Experts and officials also identified governance challenges, such as the need to address liability. GAO recommends that within the Executive Office of the President, the appropriate entities, such as the Office of Science and Technology Policy (OSTP), establish a clear strategy for geoengineering research in the context of the federal response to climate change to ensure a coordinated federal approach. OSTP neither agreed nor disagreed with our recommendation, but provided technical comments.