Geoengineering for grown-ups

A few days ago the European Union’s Earth Observation program, Copernicus, made a special announcement at the end of its monthly report on the state of the climate. It said the average global temperature for the past three years (2023-2025) has been 1.5 degrees C above the pre-industrial level. That’s the level we were warned that we must never exceed.

“For November, global temperatures were 1.54 C above pre-industrial,” said Samantha Burgess, deputy director of the Copernicus Climate Change Service. “The three-year average for 2023-2025 is on track to exceed 1.5 C for the first time.” Weirdly, the air-raid sirens did not go off. You couldn’t imagine a worse emergency, but not even the fire sirens sounded.

In fact, most traffic was heading in the opposite direction. The United States is completing its withdrawal from the Intergovernmental Panel on Climate Change for the second time. COP30, the annual conference on how well the world is doing at emissions cuts, made almost no progress in Brazil last month, and the final report didn’t even mention fossil fuels.

German chancellor Friedrich Merz is urging the EU to soften the 2035 cutoff date for the sale of combustion-engine cars. And worst of all, perhaps, there are attempts to ban even research on direct attempts to hold the heat down. By sincerely concerned people, no doubt, but chopping holes in your lifeboats is rarely a good idea.

There are loonies and fraudsters cavorting around the fringes of the geoengineering question, but the right people to talk to are the climate scientists. Doing two books on climate change (2008 and 2024), I have interviewed over half a hundred climate scientists, and I have seen a slow but steady migration among them towards a pro-geoengineering stance.

It’s not that they love the idea. They all understand that the core policy has to be ending emissions of greenhouse gases, primarily carbon dioxide and methane. But they also know that the average global temperature, like many large-scale natural processes, tends to change by sudden great lurches rather than a slow, smooth creep (the technical term is “non-linear”).

Consider, for example, the leap of almost one-third of a degree Celsius in June 2023. It was not predicted, it gave us all the warming we had been expecting down to the mid-2030s in a single bound, and it has not gone away again. The warming we have caused directly by our emissions crossed an invisible boundary, and suddenly we were at plus-1.5 C. We still are.

There are bound to be other hidden feedbacks up ahead. Indeed, the “never-exceed” average global temperature targets of plus-1.5 C (“aspirational”) and plus-2 C (“deadly serious”) were chosen by the climate change panel precisely because they hoped that staying below those levels would minimize the risk of triggering events like June 2023. A bit too optimistically, it seems.

If geoengineering can hold the temperature down by even a few tenths of a degree until we get on top of our emissions problem, hopefully within the next 30 or 40 years, that could make the difference between mere misery, expense and upheaval on the one hand, and catastrophic global dieback on the other.

This is the context within which climate scientists are now making their choices. It’s a balance of risks, but most of them are reluctantly bringing geoengineering “into the main room of the decision space,” as Johan Rockstrom, director of Germany’s Potsdam Institute for Climate Impact Research, put it.

I have never met a climate scientist who thought that geoengineering should be used as a substitute for ending greenhouse gas emissions. The entire conversation is about keeping the warming as low as possible while we work frantically to eliminate those emissions.

A majority of “early career” climate scientists now see geoengineering as necessary and inevitable, while many senior ones are still in transition.

Comically, the seniors often have trouble saying the actual word “geoengineering” (because they are recanting their previous convictions), but their meaning is clear.

“We have no choice,” Rockstrom says. “We are simply so big and so dominant that we now need to drive the vehicle. Currently we are just sitting there and not really recognizing that we are the ones with the levers now.”

Gwynne Dyer’s new book is Intervention Earth: Life-Saving Ideas from the World’s Climate Engineers.