Proposals to fight the impact of the climate crisis at the poles, from giant underwater curtains to scattering glass beads across the ice, have been dismissed by a group of scientists as an “unimaginably expensive” and “dangerous” distraction.
Geoengineering, which includes blocking sunlight with airborne particles and thickening ice with pumped seawater, has become highly divisive among scientists. Its proponents argue that, with cuts in carbon emissions going far too slowly, exploring options for “emergency brakes” would be valuable.
However, a new analysis argues that schemes proposed for polar regions are so flawed that no amount of research could resolve them and that they treat only the symptoms and not the causes of the climate emergency.
The researchers argue that continuing to investigate the schemes wastes time and funding that would be far better spent on emissions cuts. Critics of the analysis said it looked solely at the negative aspects of the geoengineering schemes and did not compare these with the damage caused by global heating.
The Arctic and Antarctic are heating much faster than the rest of the planet, with the loss of ice driving up sea levels and leading to even more heating as dark, sunlight-absorbing seas are exposed.
Rob DeConto, a professor at the University of Massachusetts Amherst in the US and one of the 42 scientists who produced the analysis, said: “These geoengineering proposals are unimaginably expensive and risky for fragile polar environments. They also detract attention from the root cause of the climate crisis – the unabated burning of fossil fuels, something we know how to begin addressing using established technologies. Counting on these geoengineering concepts to save the day is both dangerous and unrealistic.”
Martin Siegert, a University of Exeter professor who led the analysis, said: “Anyone is entitled to do research as long as it obeys guidelines of responsibility and ethics. But there comes a time when we have to look really carefully about prioritising our efforts towards what actually works.
“The [proposals] just don’t really stack up as being viable, especially within the next 30-40 years, during which time we need to decarbonise. Their impossible scale is something that you can’t research away.”
The ideas were being pushed with unjustified optimism by some researchers and foundations, he said, and by companies hoping to develop patents. “We’re hopeful that we can eliminate emissions by 2050,” Seigert added. “Anything that drifts us away from doing that will make the world less safe and less habitable.”
Even if global heating soared beyond 1.5C and 2C above preindustrial levels, Siegert said cutting emissions would still be the fastest way to restore safer temperatures.
Plans for real-world geoengineering experiments from the Arctic to the Great Barrier Reef were revealed in May, funded by the UK government. Siegert did not criticise the Advanced Research and Invention Agency programme directly but said: “How the UK spends its research and innovation money surely must be prioritised alongside its commitments to decarbonising.”
The review of polar geoengineering schemes is published in the journal Frontiers in Science. The researchers used six criteria to assess a series of proposals: effectiveness, cost, scale and time issues, environment risks, governance challenges and the risk of raising false hopes. They concluded none passed the tests.
Pumping seawater on to Arctic sea ice might artificially thicken and preserve it. But Dr Heïdi Sevestre, of the Arctic Monitoring and Assessment Programme, said: “This would require millions of devices deployed across drifting, fracturing ice. This is technologically, logistically and financially unrealistic. Moreover, the governance challenges are profound, as sea ice crosses national boundaries.”
Scattering vast numbers of tiny glass beads on the ice might help reflect more sunlight, but Prof Steven Chown, of Monash University in Australia, said the beads could be toxic to wildlife and fundamentally alter the blooming of krill and other organisms.
Perhaps the best known geoengineering proposal is to inject reflective particles into the stratosphere to block sunlight. Dr Valerie Masson-Delmotte, of the University of Paris-Saclay in France, said such a huge scheme would have to be continued for many years to avoid the “termination shock” of extremely rapid temperature rise. It would not work in winter either, she said, when the poles were in perpetual night-time.
Other ideas, like fixing giant underwater curtains to seabeds 1,000 metres deep to stop warmer water reaching and melting ice sheets, would be exceptionally hard, said Chown. Only a single ship has ever managed to reach the required location due to the extreme danger posed by giant icebergs, he said.
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Meltwater underneath glaciers lubricates their slide into the ocean and drilling deep holes to pump out this water has also been proposed. But the researchers said this might just cause another part of the ice sheet to flow faster.
The final proposal was fertilising the ocean with nutrients to stimulate phytoplankton blooms, which would draw carbon into the deep ocean when they die. As well as requiring an armada of ships, it could also reduce the oxygen in the ocean, disrupting the marine ecosystem, said Masson-Delmotte.
Dr Bethan Davies, of Newcastle University, welcomed the new analysis: “Until now, the scholarly debate has largely been one-sided, focused around those who support or conceptualise these interventions. The answering debate is long overdue.”
The researchers identified “serious scientific flaws and apparently insurmountable governance problems”, said Dr Phil Williamson, of the University of East Anglia.
However, geoengineering and other researchers criticised the review. Dr Pete Irvine, of the University of Chicago in the US and editorial director of the website SRM360, said: “Here we see a one-sided analysis that stresses only the side-effects, downsides and potential for misuse. Stratospheric aerosol injection could halt global temperature rise in a matter of years at a relatively low cost. It is not an alternative to emissions cuts, it comes with side-effects, and it could prove very challenging to govern, but it seems like it might help to greatly reduce climate risks if used wisely.”
Dr Shaun Fitzgerald, of the University of Cambridge, said: “Unfortunately, we are faced with severe environmental damage without geoengineering. So, rather than saying we should not look further into geoengineering, we should instead be seeking a debate about the relative risks.”
The analysis estimated that the geoengineering schemes would cost up to $80bn each, but Prof Matthew Watson, of the University of Bristol, said this was still less costly than large-scale emissions cuts. He said slashing emissions to zero looked “horribly unrealistic” so more knowledge was needed on geoengineering schemes before definitively ruling them out.
Prof Andrew Shepherd, of Northumbria University, said: “At some point we may have to save Earth’s ice for future generations, so it’s important we know how to do that safely. Our [research] community would be stronger and healthier if geoengineering wasn’t such a divisive issue.”
