A new report from the National Academies of Science, Engineering and Medicine addresses a controversial question: Is solar geoengineering – an approach aimed at cooling the Earth by reflecting sunlight back into space or modifying clouds – a possible tool to counter climate change?
The report, produced by a committee of 16 experts from various fields, does not stand, but concludes that the concept should be studied. It calls for the creation of a multidisciplinary research program, coordinated with other countries and administered by the U.S. Global Change Research Program, which aims to fill the vast knowledge on this issue.
The study emphasizes that such research does not replace greenhouse gas reduction and should be a minor part of the U.S. response to climate change. It notes that “realizing the climate” would not address the root cause of climate change – greenhouse gas emissions from human activities. And it calls for a research program that uses physical sciences, social sciences and ethics and includes public contributions.
These perspectives of three members of the study committee underscore the complexity of this issue.
Three options, many questions
James W. Hurrell, Professor and Scott President President of Environmental Science and Engineering, Colorado State University
Solar geoengineering strategies are highly controversial inside and outside the climate science community. It is an important step forward for 16 experts from various disciplines to agree that now is the time to establish a research program on this topic. Our committee has come a long way in achieving this recommendation, working on many complex and contentious issues to reach consensus, but we have done it collegially and productively. Each of us has learned a lot.
The three options we considered raise many questions:
– Stratosphere aerosol injection would increase the number of small reflective particles (aerosols) in the upper atmosphere to increase reflection of sunlight back into space. While there is strong evidence that this approach can cause cooling globally, there is limited understanding of how cooling potential relates to the amounts of injected aerosols, their location and type, and the subsequent regional climate responses and effects.
– Marine cloud brightening would add materials to low clouds over the ocean to further reflect them. Water vapor in clouds condenses into droplets when it comes in contact with particles, such as salt; addition of particles produces more droplets, making the clouds more reflective.
Where and how much the brightness of clouds can be modified, and whether reaction processes will mask or enhance some of the effects, are important research questions. Key processes occur on scales too small to be directly included in the current generation of global climate models, and these process uncertainties will need to be reduced to develop reliable projections of climate impacts.
– Cirrus thinning would seek to lessen the formation of thin, thin clouds that retain heat radiating upward from the earth’s surface. The effectiveness of this approach is unknown due to a very limited understanding of cirrhosis properties and the microphysical processes determining how cirrhosis can be altered. Existing climate model simulations have yielded contradictory results.
Given the risks of rapid warming and its effects, it is important to consider a portfolio of response options, and to understand as quickly and efficiently as possible whether solar geoengineering could be a fairly safe and effective option. A cross-disciplinary, coordinated and well-managed research program could prove that more investment is justified. Or it could indicate that solar geoengineering should no longer be considered. The key point is that both results will be guided by healthy science.
A thoughtful and inclusive process
Ambuj D. Sagar, Founding Chief, School of Public Policy, and Professor of Political Studies, The Indian Institute of Technology Delhi
Few climate problems are polar as well as solar geoengineering, and for good reason. To many, even considering that it could dilute efforts to reduce emissions. It also reinforces the notion that as a society we are willing to rely on ie technology to solve our self-inflicted problems.
But refusing to engage in solar geoengineering also raises questions. Can we be sure that we will not need it in the future? What if greenhouse warming generates terrible climate effects? And if it turns out that solar geoengineering is not technically feasible or socially acceptable, shouldn’t we learn that now?
This report acknowledges that it is worth understanding more about the feasibility, acceptance, risks, ethics and governance of solar geoengineering to inform decision making. But it also requires a measured, nuanced and integrated approach. And it aims that research into solar geoengineering should not compromise research or action on climate mitigation and adaptation.
Public engagement and participation, and insights from a variety of disciplines, are key to conducting effective research on solar geoengineering. At the same time, appropriate expertise and institutional arrangements are needed to better engage with this complex issue. We need to understand how to effectively improve such participation and strengthen such capacity.
Paying attention to these issues will open the door to inclusion of perspectives and researchers from the global south and other communities who are often marginalized. It will also help make the research agenda more robust and help people better understand potential risks across the world of solar geoengineering. A strong and inclusive research program must also fully involve developing countries and other relevant communities in researching governance models for solar geoengineering.
Our panel recommended that the proposed US research program be implemented in coordination with other countries. We hope that this approach will stimulate deeper engagement globally, especially from developing countries, which must be part of global conversations and decisions on this issue.
Overall, I hope that the perspectives and approaches presented in this report will catalyze a thoughtful and socially robust research program and equally thoughtful reflections by scholars, politicians, and citizens on this thorny issue.
Broadening the discussion
Marion Hourdequin, Professor of Philosophy, Colorado College
Geoengineering has evolved from a marginal concept to a serious research topic less than 20 years ago, and today solar geoengineering technologies are largely in the idea stage. Computer model simulations and natural analogues such as volcanoes indicate that adding reflective aerosols to the stratosphere or increasing the “brightness” of sea clouds could have cold effects. However, there are risks and uncertainties associated with these approaches, and the potential benefits – which may not be evenly distributed around the world – are not well understood.
For example, scientists know very little about the regional effects of different solar geoengineering strategies. And researchers are just beginning to explore the ecological, social, political, economic, and ethical dimensions of these approaches.
In addition, many people in the United States and the world are unaware that research is progressing and outside experiments have been proposed. So far discussions on solar geoengineering have been concentrated among a relatively small group of researchers, mainly from North America and Europe.
But just like climate change itself, solar geoengineering would affect everyone. The technologies our committee considered would have global and multi-generational effects. With this in mind, now is the time for broader and more inclusive conversations about how solar geoengineering should be studied and mastered – and whether it should be seriously considered or not. These conversations should include climate-vulnerable communities, indigenous peoples and nations of the global south.
Our committee’s report calls for a program that brings together multidisciplinary research, public and stakeholder engagement, and reflective boundaries and guidelines for research. This program should facilitate collaboration and capacity building, support a more demographically and geographically diverse research community, enable equitable participation, and prioritize strategies that build trust, transparency, and legitimacy.
Geoengineering poses large ie technical, technical, social and ethical questions that need to be informed by research, but cannot be adequately answered by a small group of experts. And regardless of what we learn from geoengineering research, one thing is clear: Reducing emissions, decarbonizing economies, and maintaining adaptation to current and future climate impacts must be paramount.
This article, by James W. Hurrell, Professor and Scott Presidential Chair of Environmental Sciences and Engineering, Colorado State University; Ambuj D Sagar, Founding Chief, School of Public Policy, and Professor of Political Studies at Vipula and Mahesh Chaturevdi, The Indian Institute of Technology Delhi, and Marion Hourdequin, and Professor of Philosophy, Colorado College is reissued from The Conversation under a Creative Commons license . . Read the original article.
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