# The UK’s gamble on solar geoengineering is like using aspirin for cancer

**Raymond Pierrehumbert** and **Michael Mann**

**Opinion**

**Geoengineering**

**Climate crisis**

**UK news**

**Science**

**Comment**

**US Opinion**

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**‘We have broken the climate, and solar geoengineering proposes to “fix” it by breaking a different part of the climate system.’** Photograph: Igor Do Vale/Zuma Press Wire/Rex/Shutterstock

**Opinion**

Some years ago in the pages of the Guardian, we  about the increasing attention being paid to solar geoengineering – a  scheme to cancel global heating by putting pollutants in the atmosphere that dim the sun by reflecting some sunlight back to space.

In one widely touted proposition, fleets of aircraft would continually inject sulphur compounds into the upper atmosphere, simulating the effects of a massive array of volcanoes erupting continuously. In essence, we have broken the climate by releasing gigatonnes of fossil-fuel carbon dioxide, and solar geoengineering proposes to “fix” it by breaking a very different part of the climate system.

The fix is more like taking aspirin for cancer, treating symptoms but leaving the underlying malignancy to keep growing. It poses arguably unsurmountable governance issues in our turbulent modern political environment. And if we become reliant on solar geoengineering, the world will be left subject to a catastrophic  if the intervention is ever halted – any time during the next millennium or even longer.

Since our 2021 commentary, the situation has grown far worse, with tens of millions of dollars pouring into the scheme, mostly from private philanthropy. Bill Gates was an early backer, and the tech and fintech industries have piled on since. But we never imagined that the UK government itself would be leading the charge into what is almost universally recognized as the most dangerous and destabilizing sort of research: field trials. That is precisely the emphasis as the UK’s Advanced Research and Invention Agency (Aria)  $58m for solar geoengineering research and development. Outdoor experimentation is such a controversial undertaking that even the Simons Foundation, which funds research in solar geoengineering, has shied away from making grants in this area.

Aria, with an initial budget of £800m, arose from the fevered dreams of  at the height of the  crony capitalism years. After a , Cummings’s legacy lives on in the current Labour government, which seems to have lost track of what Aria is doing. Aria, a wannabe clone of the US Defense Advanced Projects Agency (Darpa), works in darkness. It is not subject to freedom of information requests. It gives a pot of money to each of its (often inexperienced) directors, to direct expenditure largely as they wish, with only minimal peer review. The director in charge of the solar geoengineeering project is Mark Symes, an electrochemist with no background in climate science.

It is ironic that Aria is funding a project that is not only a waste of money but is actively harmful, at a time when the chancellor, Rachel Reeves, is busily hunting for places to cut government expenditures. Surely this project should count as low-hanging fruit for Reeves’s sharp scissors.

The Aria programme  on “cooling the Earth” makes for chilling reading. The project goes all-in on the supposed need for field trials, without making a case that such trials could answer any of the really important questions about what would happen with a sustained global-scale deployment. That the trials are described as “small scale” is little comfort, because even small-scale trials risk developing the technology somebody else (think Musk, Trump or Putin) might use for a large-scale deployment. (The Adam McKay film   the existential threat of a geoengineering-happy Musk-like plutocrat).

There is extreme danger in launching such field trials into an environment with neither national nor international governance in place. The only governance would be that imposed by Aria directors, who are accountable to basically nobody. Worse, Aria can fund projects outside the UK, which invites shopping for sites with poor environmental regulations and limited opportunities for public protest. Provision of government funding for crossing the Rubicon to outdoor experimentation will inevitably legitimise such programmes, opening the floodgates for yet more money to pour into developing geoengineering technology worldwide. And once the engineers involved realise, as they inevitably will, that “small scale” experiments do not answer any of the truly critical questions, there will be demand for ever-larger trials, putting us on a slippery slope to full-scale deployment.

The Aria geoengineering programme is a dangerous distraction from the work that needs to be done to achieve net-zero carbon dioxide emissions. The net-zero goal is one that is enshrined in UK law, and one that the Labour government purports to uphold. The UK government should not encourage false solutions like solar geoengineering and the people of the UK should not stand for it.

Aria is already evaluating proposals for its dangerous project. It is not too late to halt this juggernaut, but to do so will require vigorous pushback that starts right now.

* Raymond T Pierrehumbert FRS is professor of planetary physics at the University of Oxford. He is an author of the 2015 US National Academy of Sciences report on climate intervention
* Michael E Mann ForMemRS is presidential distinguished professor at the University of Pennsylvania. He is the author of 
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