Study finds that climate engineering off US coast could increase heatwave in Europe

[객원 에디터 7기 / 이석현 기자] A geoengineering technique to reduce high temperatures in California can inadvertently intensify heatwaves in Europe. A study published in Nature Climate Change models the unintended consequences of regional climate interventions.

The technique, known as marine cloud brightening, sprays reflective aerosols such as sea salt into stratocumulus clouds over the ocean. This process increases the clouds’ reflectivity, bouncing more solar radiation back into space to cool the targeted area. However, the authors warn that while this method offers temporary benefits, it can also cause negative side-effects in other regions of the world.

The findings are particularly concerning because there are few regulations in place to prevent regional applications of marine cloud brightening. Without global governance, countries, cities, companies, or wealthy individuals can modify local climates to the detriment of other regions, potentially leading to competition and conflict over climate interventions.

The sharp rise in global temperatures has increased interest in geoengineering research, which was previously considered taboo. For at least four years, researchers in Australia have been experimenting with marine cloud brightening to cool the Great Barrier Reef and reduce its bleaching. Earlier this year, the University of Washington conducted a sea-salt particle spraying experiment on the USS Hornet in San Francisco Bay, which was halted by the local government due to health concerns.

The study used Earth system computer models to simulate the impacts of cloud brightening operations in 2010 and 2050 over the north-eastern Pacific Ocean. Two regions were targeted: the subtropics near California and the mid-latitudes near Alaska. The simulations revealed that the more distant operation near Alaska had a greater impact due to teleconnections, or links in the climate system between remote regions.

In 2010, the Alaska operation reduced dangerous heat exposure by 55% on the US west coast, equivalent to 22 million people-days per summer. The California operation provided a 16% reduction. However, with fewer clouds, higher base temperatures, and a slowing Atlantic meridional overturning circulation, the effectiveness of these operations diminished by 2050. The Alaska operation’s impact was drastically reduced, while the California operation actually increased local temperatures.

The study also found that the 2010 simulations suggested European cooling benefits from the Alaska operation. By 2050, however, local cooling efforts increased heat stress globally, particularly in Europe, due to the slowed Amoc.

Jessica Wan, a member of the research team at UC San Diego’s Scripps Institution of Oceanography, emphasized the need for policymakers to establish governance structures and transparent guidelines for solar geoengineering.

“Our study shows that marine cloud brightening can be effective for the US west coast now, but it may be ineffective in the future and could cause heatwaves in Europe,” Jessica Wan said according to The Guardian. “Science and policy need to be developed together to avoid regions being forced into geoengineering to counteract the actions of others.”

Without robust governance, the well-intentioned efforts of one region could inadvertently exacerbate climate challenges elsewhere.

Sources: The Guardian, Hacker News, Common Dreams