While the effects of climate change are typically discussed in abstract future terms, its impacts are already overwhelming the resources of a growing number of developing countries. The scale of climate change impacts and vulnerabilities in these developing countries warrants serious and inclusive international dialogue on geoengineering, and in particular a promising technology that aims to reflect a small percentage of sunlight back into space called Solar Radiation Management (SRM). There remains the possibility that SRM could complement mitigation and adaptation in the fight against climate change, but not without simultaneous increases in resources for research and informed debate that is grounded in the needs of those most affected by climate change right now.

UN Photo

Climate change is not a problem of the future - at least not exclusively. Yet almost always missing from the talking points of Western leaders, even those most attuned to the scale and nuance of the problem, is that the negative impacts of climate change are already being felt today. And almost totally absent from the dialogue (in the United States at least) is the fact that, in some countries, these impacts are overwhelming the capabilities of individuals, communities and societies to adapt. Meanwhile, there are not many climate 'skeptics' in the most vulnerable developing countries. In these countries, people are not debating climate change - they are living it.

This does not detract from the fact that the problem of climate change is growing and that it will not begin slowing until long after global emissions have peaked. Since it is the stock of greenhouse gases (GHGs), particularly carbon dioxide, in the atmosphere and not the flow of emissions that underlies the process of global warming, as long as the atmospheric concentration of GHGs is increasing, so too will the impacts of climate change. Those most affected by the impacts of climate change now, who primarily live in developing countries, will also tend to face the most severe impacts in the future. The vulnerabilities of these people - billions of people - dictate that we should take the idea of solar radiation management (SRM), also known as solar geoengineering, more seriously than we have to date.

SRM encompasses a range of technologies that aim to reflect a small percentage of sunlight back into space before it reaches the Earth’s surface, thereby decreasing radiative forcing and helping to slow the rate of global temperature increase. The most promising SRM technology developed to date involves the dispersion of a controlled amount of sulfate aerosols into the stratosphere using specially-equipped high altitude planes. This would aim to mimic the cooling effect observed after such particles are released by volcanoes. As opposed to other geoengineering technologies that aim to directly remove carbon dioxide from the atmosphere, which might become feasible on a large-scale in the future, SRM using sulfate aerosols may be feasible to implement quickly and provide a cooling effect for the entire planet at astonishingly low implementation costs1. As such, it would be neither a perfect nor sufficient response to climate change, but it could potentially help.

Robert Stanhope, Harvard University

Taking the idea of SRM more seriously means marshaling far more resources for research and international dialogue. We must build a global effort to better understand both the potential benefits and the broader costs and risks of SRM technologies. Research and dialogue might show that SRM would be an effective and feasible tool for complementing mitigation and adaptation in global efforts to combat climate change. Alternatively, increased scrutiny might show that implementing SRM in any form would be untenable. While the latter outcome might be more likely, the former could mean the prevention of a tremendous amount of human suffering. A sober review of the current body of academic research on SRM leads to the conclusion that either outcome remains possible, and this uncertainty is precisely why more research and dialogue, inclusive of those most affected by climate change, is needed.

Climate change hits the poorest nations

The effects of climate change are now clear to observe on a global scale. The Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) shows with more clarity than ever before that our planet is warming, the water cycle is accelerating, weather patterns are shifting, sea level is rising and oceans are acidifying. These are huge changes, but listing the changes alone does little to elucidate the problem, which is how these changes impact people. This distinction between changes and impacts is rarely made in many developed countries, and this is not surprising since developed countries have rarely encountered climate change impacts that have stretched their adaptation capabilities. But most people do not live in developed countries, and in many developing countries climate change impacts have become severe. Since these impacts are too often overlooked, it is worth pausing to consider a few examples of how the changing climate system is impacting people worldwide.

Global warming, reflected by systematic increases in global mean temperature, has not meant elevated temperatures everywhere or at all times. It has, however, meant that most places are experiencing more hot days and fewer cool days. This does not mean too much when one has air conditioning, but this year heat waves in May-June killed approximately 2,500 people in India and at least another 1,200 people in Pakistan. Much more regularly, crops are strained and can ultimately fail, and livestock grow ill and ultimately die, when temperatures are too high, especially when farmers do not have the necessary information (from an effective weather bureau) or the necessary inputs (like irrigation systems or fertilizer) to respond to hot stretches. And when a crop fails for a subsistence farmer without crop insurance or savings, it does not just mean lost income for the season, it often means hunger and malnutrition. In countries like Ethiopia or Cambodia, where well over 50 percent of the workforce is employed in agriculture (versus 2 percent in the U.S. and less than 5 percent in most countries in Europe), agricultural shocks can quickly cripple the entire economy.

But those are just some impacts from warming itself. The impacts resulting from an accelerated global water cycle tend to be much more consequential. Most regions of the world are now experiencing more intense rainfall cycles - with heavier rains concentrated in shorter rainy seasons and more periods of drought during prolonged dry seasons. In tropical countries, where so much of life revolves around rainfall patterns, flooding and drought both pose immense challenges. Part of developing countries’ vulnerability again derives from the high shares of employment and output in agriculture. But floods also cause massive damage and loss of life, especially in underdeveloped urban areas, while droughts often lead to larger problems of water scarcity. Furthermore, while the link between climate change and extreme weather events, like hurricanes or typhoons, is not well understood, the occurrence of the most severe forms of such events is likely to increase as time progresses. Such extreme weather events are often devastating in developing countries, especially when they strike in areas without historical precedent. In 2013, Typhoon Haiyan in the Philippines, which was both record-breaking in intensity and struck an area that was not prepared, killed over 7,300 people and created damage worth around 3.7 percent of GDP.

Then there are the impacts from changes to the planet’s oceans. Average sea levels have risen by approximately 0.2 meters since 1900, and the world is locked into more sea level rise well into the future as ocean water expands and glaciers melt. Although this might seem a small change, major impacts are already being felt long before any island nation faces the immediate threat of submergence. Communities are gradually becoming unlivable as a result of saltwater intrusion into water supplies and productive land, as well by as the erosion of coastal land. Emigration is on the rise. At the same time, ongoing ocean acidification, the result of increased uptake of carbon dioxide in the oceans, gets less attention but poses the catastrophic threat of mass marine extinctions. Such extinctions would acutely affect around one billion people worldwide, mostly in developing countries, who rely on seafood as their primary source of protein.

So when one unpacks the occurrence of climate change impacts happening already, it becomes apparent that the ultimate irony of climate change is that those least responsible for the problem tend to be those most affected. Those individuals and communities in developing countries with far higher exposure and sensitivities to climate change impacts also tend to have a lower ability to adapt, as both the necessary resources and required state capability are usually extremely limited.

What is the role of SRM?

SRM can be a frightening concept, but it must be taken seriously because climate change itself is just as frightening, and perhaps more so, in many places. And while SRM, and geoengineering of any kind, would involve deliberately altering the climate system, our emissions of greenhouse gases have been (accidentally) altering the climate system for centuries now. So could SRM be an effective tool for combating climate change?

The answer is most definitely maybe. There is still far too little understood about the degree to which the technology could actually work in reducing the impacts of climate change, especially on a region by region basis, and there are far too many unknowns about potential side effects of the technology to justify the use of SRM today. It is also clear that SRM would do nothing to reduce the problem of ocean acidification or any of the other direct impacts of higher atmospheric concentrations of carbon dioxide and other GHGs. But scientific evidence continues to show that SRM might be effective in reducing many impacts of climate change by slowing the rise in global mean temperature. If SRM could be a tool to help avoid some of the suffering that climate change impacts will increasingly cause in developing countries, it must be considered as part of the climate change response toolkit.

SRM could interact with the climate system in complex ways. Some vulnerable countries could benefit by its use (through the reduction of negative climate change impacts) while others could be harmed (through the intensification of climate change impacts or new harmful side effects). The same is also true within countries. The known possible side effects of SRM using stratospheric sulfate aerosols are very serious, including potential ozone depletion, changes to plant growth, and shifts in regional weather patterns, among others2, but they might turn out to be manageable. Currently, there is simply not enough understood about SRM to sufficiently weigh its potential benefits and its potential costs. But there is a clear case for increasing research on SRM to clarify the scale of benefits and risks and to reduce uncertainty.

One thing that is clear, for several reasons, is that the framing that has been popularly used for SRM as a 'last resort' or an 'emergency fix' is not appropriate. SRM would be inappropriate as an emergency measure because the risks would likely increase with the intensity of its use, and because SRM could never fully offset all of the negative impacts of climate change. Moreover, tying the deployment of SRM to any form of 'climate emergency' would be unworkable in reality3.

SRM would be a much more appropriate technology to use early rather than late, and in small rather than large amounts. If research were to show that SRM could help to reduce some of the worst impacts of climate change and that the risks would be manageable, the most appropriate way to use it would be as a bridge technology - one that is used temporarily to help limit the effects of climate change while the world moves to a zero-carbon-emissions future. Consistent with this framing, a hypothetical SRM usage rule that would link the use of SRM to global emissions reductions was recently suggested by David Keith and Douglas MacMartin4. Keith and MacMartin do not claim that they identified an optimal usage rule, but they do provide a reasonable scenario where SRM could begin in 2020, peak in intensity around 2060, and be near zero by 2150.

Free-rider or free-driver?

Beyond the scientific questions around whether SRM could be an effective tool to complement mitigation and adaptation in the fight against climate change, there are also large governance questions. Climate change itself has long posed an immense challenge to global governance systems because of the free-rider nature of the problem: individual countries have been unwilling to undertake the required private costs (of emissions reductions) to provide the global public good (of less climate change). But now there is a growing recognition that the costs are lower and the benefits higher than previously thought for many major emitters, and that the free-rider problem might be partially overcome by ambitious actions by a large but not necessarily universal group of countries.

SRM, meanwhile, presents a very different global governance challenge that has been characterized as a free-driver5 rather than a free-rider problem. With a free-driver problem, the private costs (of implementing SRM) may be low enough to result in its use by one country without regard for the welfare of those in other countries. Unlike with climate change mitigation, where the problem is too little action, there is potential for the problem with SRM to be too much of it. This is complicated further by the fact that different countries would prefer the global mean temperature at different levels, since temperate countries might believe they benefit from global warming in some ways in which tropical countries suffer.

SRM implementation would therefore require a level of international consensus that has been rarely seen in the course of human history. Currently there is no international framework or body to begin to govern decisions on SRM, including regarding research. Therefore, if one country or one group of countries did begin to use SRM, other countries would have no formal mechanism through which to respond. Furthermore, given that very little research is currently being conducted on SRM, early implementation by one country would leave all other countries with enormous uncertainty over how they would be affected.

There is a need to increase research into SRM and to broaden dialogue and international discussion on SRM to include developing countries. As with climate change itself, developing countries would likely be most affected by the use of SRM (whether that is beneficial or not), but they remain largely left out of the conversation. My own limited engagement with climate change policymakers in developing countries suggests that many are not familiar with the concept of SRM, even in countries that have been the most proactive and successful in their responses to climate change adaptation. Meanwhile, scientists in many developing countries have expertise to apply to SRM research that Western scientists do not - particularly regarding the interactions between SRM, agriculture and water resources.

In my own conversations in the Philippines in September 2015, for example, some climate scientists were aware of the concept of SRM but climate-related policymakers from all government levels were not. During 19 one-on-one and small group interviews I conducted with national and local government officials, community representatives and scientists, after being introduced to the concept all interviewees voiced support of increased SRM research and nearly all supported the use of field-based experiments. Most interviewees felt that the Philippines should begin its own research program on SRM, and nearly all felt that there should be an international forum for guiding future decisions on SRM. This tiny number of interviews does not constitute any type of meaningful survey of opinion, but the conversations do underscore the importance of open and inclusive dialogue. Several of the interviewees explicitly expressed concern that the needs of a vulnerable country like theirs are not being adequately considered by parties that would dismiss the idea of SRM outright.

SRM should be on the table

Although it is not a particularly new idea, SRM has only recently emerged, along with the topic of geoengineering more generally, from the outskirts of the academic and scientific community. This allows the technology behind SRM to begin to be treated with the seriousness that it deserves. While SRM elicits a strong negative reaction by many because of the substantial risks that it raises and fears of overambitious implementation, the potentially significant benefits of SRM mean that 'premature rejection' of SRM and inadequate research funding also pose a major concern6. The recent emergence of the topic from academic obscurity has, in part, reflected the need for such balance.

Most of what must be done to slow climate change, decrease vulnerabilities, and increase resilience has little to do with SRM and everything to do with climate change mitigation and adaptation. However, there remains the possibility that SRM could complement mitigation and adaptation by directly reducing the impacts of climate change, especially if used as a bridge technology. Yet, far too little research is currently being conducted on SRM to understand if and how it would affect the climate system and those most vulnerable to climate change. Furthermore, developing countries, which would likely be affected most by the use of SRM, remain largely excluded from international dialogue on the topic. This is deeply unfortunate, unjust and wrong.

Despite the progress in building an inclusive foundation for climate change action through intended nationally determined contributions (INDCs) via the current United Nations Framework Convention on Climate Change (UNFCCC) process, it is clear that current contributions will fall short of what is needed to keep global temperature rise under the reasonable goal of 2 degrees Celsius. Furthermore, contributions will not go nearly far enough toward meeting the adaptation needs of developing countries. The time is right to add discussions on SRM to the global agenda. The way forward should include the creation of an international forum for informed debate on SRM and substantial increases in resources for research into SRM in the short term. In the medium and longer term, it is those who are most affected by climate change that should have the right to lead discussion on this topic.