Can geoengineering avert a climate catastrophe?

{"text":[[{"start":6.4,"text":"The writer is a science commentator"}],[{"start":8.5,"text":"Dam that strait. Not a misspelt venting of frustration about the effective closure of the Strait of Hormuz, but an eye-catching proposal from climate scientists about a different waterway entirely. "}],[{"start":19.5,"text":"Researchers in the Netherlands have floated the idea of building a dam across the Bering Strait, the shallow 85km-wide channel separating Alaska from Siberia. The closure, they suggest, could help to stabilise ocean currents crucial for regulating the climate. "}],[{"start":35.15,"text":"In engineering terms, the proposal is not orders of magnitude adrift of other marine megaprojects, such as South Korea’s record-breaking 34km Saemangeum Seawall. In geopolitical terms, with its need for long-term American and Russian co-operation, it seems preposterous. "}],[{"start":54.55,"text":"Its real value, however, lies in the fact that it has been broached at all. In an increasingly unstable world, climate targets have slipped from view. Complacency about reducing emissions today is likely to heighten the call for more drastic action tomorrow. Against this background, the very madness of extreme geoengineering alternatives is the message. "}],[{"start":76.5,"text":"At the heart of the concept lies the Atlantic Meridional Overturning Circulation (Amoc), a conveyor belt of ocean currents that shift warm waters from the tropics northwards. The water cools, becoming denser, and sinks before sloshing back southwards. "}],[{"start":92.6,"text":"That cycling — into which the Gulf Stream feeds — redistributes heat, carbon, salt and other nutrients in the ocean and helps to set climate patterns. But global warming is tugging on the conveyor belt, with melting ice interfering with the circulation. The Amoc is slowing and, according to some models, might collapse altogether in the coming decades. "}],[{"start":115.85,"text":"“A substantial weakening [of Amoc] could have significant impacts, including shifting rainfall patterns, increasing sea levels along the US east coast, changing European climate, and reducing ocean carbon uptake,” explained Jon Baker, a UK Met Office scientist who studies Amoc but was not involved in the new research. "}],[{"start":137.4,"text":"Researchers Jelle Soons and Henk Dijkstra, from Utrecht University, decided to simulate whether closing the Bering Strait might avert an Amoc shutdown, long regarded as a climate tipping point (when the climate suddenly changes irreversibly). Their approach was inspired by two clues: first, the strait is a gateway for fresh water flowing from the Pacific to the Atlantic via the Arctic, which has a net weakening effect; second, a previous study showed the conveyor belt was stronger about 3mn years ago, when sea levels were lower and the strait was a land bridge. "}],[{"start":169.7,"text":"Running the numbers showed that, under certain conditions, a dam “could be a feasible climate intervention strategy”, the pair wrote last month in the journal Science Advances. “It was a very exciting moment when a simulation showed that a closure of the strait can prevent a collapse,” Soons told me. "}],[{"start":187.85,"text":"But the paper also shows that timing is everything: closing the strait when the conveyor belt is already weak could make matters worse. Soons said the calculations are intended as a proof of concept but a dam could be “a possible measure in a worst-case scenario”. The researchers stress that the engineering details are beyond the scope of their paper."}],[{"start":208.65,"text":"For others, massive geoengineering climate fixes are themselves the worst-case scenarios. A spokesman for the Met Office told the FT: “The Met Office does not advocate geoengineering solutions to climate change, which can often bring dramatic and unintended consequences . . . Fighting to stave off every fraction of a degree rise of global temperature is the more sustainable and pragmatic approach.” "}],[{"start":233.35,"text":"There are other obstacles besides: damming the strait completely, as modelled, would seal off a migration route for mammals and disrupt coastal indigenous communities. It would scupper a vital shipping route. The waterway — named after Danish-born explorer Vitus Bering, who led expeditions for the Russian Navy — is used by Russian tankers, bulk carriers and LNG carriers, and for tugs and barges serving Alaskan coastal communities, as well as transporting mined ore. "}],[{"start":263.5,"text":"In addition, many aspects of the Amoc remain poorly understood, including how stable the conveyor belt is under future warming scenarios and how close it is to any tipping point. The Utrecht researchers deserve kudos for showcasing this costly, speculative and politically impossible megaproject, if only to remind us how vital it is to keep existing climate commitments afloat. "}],[{"start":null,"text":"

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"}],[{"start":286.05,"text":"Letters in response to this comment:"}],[{"start":288.3,"text":"Climate interventions also need their own governance / From Professor Nayef Al-Rodhan, Honorary Fellow at St Antony’s College, University of Oxford, and Head of the Geopolitics & Global Futures Department, Geneva Centre for Security Policy"}],[{"start":302.6,"text":"Indigenous peoples need a say in the climate debate / From Richard G Little, Industry Advisory Council, Department of Industrial & Systems Engineering, Rensselaer Polytechnic Institute, Williamsburg, VA, US"}],[{"start":321.40000000000003,"text":""}]],"url":"https://audio.ftcn.net.cn/album/a_1779859195_5344.mp3"}