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What is SRM?

Solar radiation modification (SRM) is a controversial proposal for reducing some of the impacts of climate change by reflecting a small fraction of sunlight away from the Earth.

While there are a number of proposed techniques for reflecting sunlight through SRM, Degrees’ modelling teams focus on stratospheric aerosol injection. This form of SRM proposes injecting tiny reflective aerosols into the upper atmosphere to replicate the cooling effect of major volcanic eruptions.

SRM approaches remain theoretical—no one is deploying the technology and there have only been a few small outdoors experiments. In general the evidence that we have on SRM’s impacts comes from observing the climate effects of volcanic eruptions, and from computer modelling research, where scientists use climate models to evaluate how SRM might reduce, increase, or alter the impacts of global warming.

SRM is no one’s preferred way to deal with the risks of climate change. It would involve directly intervening in the Earth’s climate system and it has some serious risks and large unknowns. But it’s being considered because it’s the only known way to quickly slow or reverse the rise in global temperatures, and it therefore might prove a useful complement to controlling greenhouse gases and adapting to the effects of warming.

The world is not on track to meet its international climate change goals and impacts are rising. With current climate policies, warming is projected to rise beyond 2.5C and the climate-vulnerable countries of the Global South are going to suffer most.

Ending greenhouse gas emissions is the primary strategy to limit global warming. Adaptation can help limit risks from increasing warming. Carbon dioxide removal will also play an increasing role. However, collectively, these forms of action may not be enough to sufficiently limit risks.

Scientists are therefore trying to understand whether SRM could help reduce the impacts of warming while humanity is eliminating greenhouse gas emissions. 

SRM could be very helpful or very harmful. It is the only known way to quickly stop or reverse the rise in global temperatures, and could be the only way to keep warming below 2°C if mitigation proves insufficient.

But it could also have damaging side effects, could cause political tensions, and could distract politicians from cutting emissions. The stakes are high and nowhere are they higher than in developing countries, which are on the front lines of climate change. If SRM could work to reduce climate impacts, they stand to gain the most. But if SRM goes wrong—or is rejected prematurely—they stand to lose the most.

Historically, most SRM research has taken place in the Global North. A laissez-faire approach would mean the gulf will continue to widen. It is therefore critical that the countries of the Global South play a more central role in the evaluation of SRM.

The more Global South experts understand SRM and its implications, the better placed they will be to stand up for their interests, and to resist any bad-faith attempts to persuade them to support or oppose SRM.

About the Degrees Initiative

Since 2010, the Degrees Initiative has led the world in building developing country capacity to evaluate SRM and to play a central role in the global conversation around this controversial technology. 

Degrees’ engagement workshops—more than 30 thus far—in developing countries bring new voices into the global conversation. The Degrees Modelling Fund has empowered 24 teams of scientists in the Global South to ask their own questions about SRM and develop their own expertise and its community-building activities promote South-South and South-North collaboration around SRM. This offers a template for our new Socio-Political Fund.

Together, these activities are creating a global community of SRM experts with strong southern representation, transforming the environment in which decisions about SRM will be made by ensuring informed and confident representation from climate-vulnerable countries. 

The Degrees Initiative is neutral on SRM—on whether it should ever be used and how it should be governed. But we believe that much more research is needed if humanity is to make informed decisions about SRM, and a much broader conversation is needed if there are to be equitable decisions. 

Degrees’ work has received widespread acclaim. Degrees was singled out for commendation in a report on SRM from the US National Academy of Sciences and its model was endorsed by the editors of Nature. It was selected as one of the ten Scale-Up projects of the 2021 Paris Peace Forum and the Rockefeller Foundation granted it a convening at their Bellagio Centre in February 2023. The initiative’s work has been covered by major media outlets, including The Guardian, the BBC, Le Monde, Nature, Carbon Brief, Climate Home News, the Huffington Post, the Japan Times, Reuters, and SciDevNet.

The Degrees Initiative is a registered charity in England and Wales. It was previously known as the SRM Governance Initiative (SRMGI), a partnership between the Royal Society, The World Academy of Sciences (TWAS), and Environmental Defense Fund (EDF). Degrees is currently funded by Open Philanthropy. Previous funding sources include Climate Pathfinders Foundation, the InterAcademy Panel (IAP), the European Climate Foundation, Zennström Philanthropies, the Carbon War Room, the Safe Climate Research Initiative (LowerCarbon Capital, Matt Cohler, the Pritzker Innovation Fund, Bill Trenchard, and the LAD Climate Fund) and the Fund for Innovative Climate and Energy Research (FICER).