Step up geoengineering research, EU science advisers recommend

The EU’s panel of science advisers has called for more research into geoengineering, to understand the feasibility – and potential risks – of trying to block out the sun to cool a warming earth. 

Solar radiation modification (SRM), as it’s often called, is one of the most controversial topics in the research world, with some academics pushing to better understand how it could work, while others are highly sceptical in case scientific study makes risky deployment more likely. 

A trio of reports released earlier this week threads a middle path. The key document, from the European Commission’s group of chief scientific advisers, wants more research into how SRM would work, but also stresses that it’s far from proven right now. 

“We as scientists are in favour of knowing more, it’s a no brainer,” said Johannes Quaas, a metrologist at the University of Leipzig who helped compile the evidence base for the advisers’ recommendations. 

As to whether the recommendations will translate into EU policy, the Commission did not respond before Science|Business’s deadline. 

SRM encompasses ideas including brightening marine clouds to reflect light back into space, or launching a space mirror to block out the sun. But the most feasible option for now is called stratospheric aerosol injection, in which a fleet of planes continuously spray tiny particles into the high atmosphere, mimicking the cooling effects of a volcano. 

But the report warns there is “currently insufficient scientific evidence that SRM would effectively help to avoid dangerous climate change.” While existing climate models do suggest SRM could mask global warming, new risks might arise, including unexpected local effects on rainfall and food production. 

“These technologies do show some promise, but they are far from mature,” said research commissioner Ekaterina Zaharieva in a statement. 

The advisers want more research to fill in the gaps. “The high uncertainties in the potential benefits and risks of SRM can only be addressed by further research (as in any other field), ideally supported by public funding,” they say. This includes how aerosols would interact with clouds, their spread through the climate, delivery mechanisms of SRM, and the risks. 

Even if the EU choses never to deploy SRM, it’s important to understand how it could work, in order to broker any international agreements on use, the advisers say.

But there are many caveats. Outdoor trials of SRM risk “creating the impression” that it “might become a feasible option,” the advisers warn. Any research programme needs to make sure it can’t be used to promote a “slippery slope” from research to deployment. 

There should be a moratorium on “large-scale” outdoor experiments. SRM research funding should also not be at the expense of money for other types of climate research, they recommend – although scientists say disentangling SRM research from general climate modelling work is difficult. 

The scientific advisers want the EU to reassess the scientific evidence on SRM every 5-10 years, to see whether it looks more promising than currently, or if risks are so great it should be permanently banned. 

Funding landscape

There isn’t good recent data on who is funding SRM research, but a Harvard University tally to 2018 found that Europe was a key public funder in the 2010s, but then dropped off, replaced by largely private funding in the US.

One of the most prominent, the Harvard Solar Geoengineering Research Program, is backed by numerous wealthy individuals and foundations, including Bill Gates. The programme had to call off a test balloon launch in Sweden in 2021 after local objections. 

In 2023, at the request of Congress, the White House put out a plan for geoengineering research – although stressed its focus was on reducing greenhouse gas emissions.  

“Most of the research in the world is being done in the US, by academics,” said Cynthia Scharf, a geoengineering expert at the Centre for Future Generations, a Brussels-based think tank.

“Right now there isn’t public funded research in the EU,” but backing more would give Brussels extra clout in any future discussions, she said. 

Scharf stressed that research shouldn’t be done with a presumption of deployment. “One of the most important reasons to research is to ask: is this just an insane idea?” she said. 

The UK has recently stepped up its research efforts. Earlier this year, the country’s Natural Environment Research Council said it would invest £10.5 million over five years into SRM deployment, although only through modelling and lab work, not outdoor experiments. The country’s Advanced Research and Invention Agency (ARIA) also has a £56.8 million programme into  short-term “climate cooling” to avoid climate tipping points. 

Lagging behind

The EU’s Horizon Europe only funds one SRM-related research project, and that’s about how to govern research, rather than deployment itself- 

“Europe is lagging behind in terms of research into this topic,” said Peter Irvine, a geoengineering researcher at the University of Chicago. “If Europe hopes to influence the emerging debate on solar geoengineering, they'll want to fund research so that European perspectives feature in the literature and so that European leaders are well-informed.” 

However, more research will never completely erase uncertainty over the consequences of spraying aerosols into the atmosphere, stressed Quaas. “It’s always a gamble, and we will never be able to predict the outcome.” 

But this kind of doubt is no different from current climate science, argued Irvine. “It'll be like climate change in that we can't eliminate the uncertainties, but we could nevertheless make many important claims with confidence,” he said. 

There was a split among the academics convened by Science Advice for Policy by European Academies (Sapea) to build up evidence about SRM for the EU, Quaas acknowledged. 

While natural scientists typically wanted more SRM research, some social scientists and governance experts were against any further investigation. 

“For me, it is a very strange notion to prohibit understanding something,” he said. 

A ‘battlefield’

Some academics are indeed sceptical of calls for more research. More than 500 have signed a call for an international non-use agreement, and hit back at what they describe as the “increasing normalisation of solar geoengineering research.” 

They warn that SRM’s impacts “can never be fully known”, might disincentivise decarbonisation, and would be near impossible to govern globally in a democratic way. 

One of the call’s initiators, Jeroen Oomen, an interdisciplinary researcher based at Utrecht University, said he was “quite pleased” that the EU’s science advisers have called for a moratorium on use. 

However, what counts as “responsible research” will now become a “battlefield”, he said. Oomen called ARIA’s climate cooling programme “completely irresponsible” because “they simply do not understand the (geo)political realities in which they are injecting these technologies”. 

One of the worries is that a small group of richer countries could deploy SRM over the objections of most of the world. The Pacific island state of Vanuatu recently supported a non-use agreement, warning that SRM could trigger local weather changes that would wreck the islands’ agriculture. 

Some African countries have also objected at the United Nations for similar reasons. 

Another risk is that SRM creates conflict with countries that benefit from climate change. Warming could, for example, melt Arctic sea ice, allowing a lucrative new shipping passage over Russia between Europe and Asia. Russia would be a “wildcard” in any future negotiations, said Scharf. 

The EU science advisers want the bloc to negotiate a global governance system around SRM, although Brussels’ position should be against use “in the foreseeable future.” 

The practicalities

The report also cautions that even volcano-mimicking aerosol injection by a fleet of planes would take a while to get off the ground.

Estimates of what it would cost per year to cool the planet by 1 degree vary wildly, from $18 billion - $107 billion, with real costs that “could potentially be substantially higher”. 

Aircraft that could fly high enough “do not yet exist” and the “development and production of a fleet of delivery aircraft that do not yet exist would likely take decades,” it says. 

These planes would need to fly around the clock for years, until emissions are reduced to at least net zero, the report warns, to avoid what’s called a “termination shock” – the sudden warming of the planet as SRM is removed.