Research press release


Nature Geoscience

Stabilizing the climate on land could have oceanic repercussions



John Fasulloたちは、硫酸塩エーロゾルを両半球の緯度15度および30度の成層圏に戦略的に注入して安定した気候を生み出すことを目的とした、気候地球工学的手法の構想のシミュレーションを解析した。その結果、この地球工学的手法は確かに、地表の温暖化と温度勾配の変化の両方を軽減させ、地域的な温度と降雨量への悪影響を最小限にすることが明らかになった。しかし、今回のシミュレーションでは、特にグリーンランド南部近傍で、海洋温暖化をもたらす可能性がある海洋循環の変化も生じた。Fasulloたちは、気候地球工学的手法の影響は、現在のところ完璧な信頼度を持って評価することはできないと警鐘を鳴らしている。

Injecting sulfate aerosols into the stratosphere to minimize changes in both surface temperature and rainfall over land may affect ocean circulation and may be less effective at cooling the deep and polar oceans than in cooling the atmosphere, suggests a paper published online this week in Nature Geoscience. These effects could result in geoengineering only slowing sea-level rise rather than halting it.

Managing incoming solar radiation by enhancing the Earth’s reflectivity has been discussed as a potential way to offset the climate warming caused by greenhouse gas emissions. However, this approach is controversial because it has the potential for significant side effects, such as reducing rainfall over land and shifting regional and seasonal temperature patterns.

John Fasullo and colleagues analyse simulations of a climate geoengineering scheme that aims to produce a stable climate by strategically injecting sulfate aerosols into the stratosphere at 15° and 30° latitude in both hemispheres. They find that the geoengineering would indeed reduce both surface warming and changes in temperature gradients, as well as minimize the adverse impacts on regional temperatures and rainfall levels. However, the simulations also produce a change in oceanic circulation that could lead to continued ocean warming, particularly near southern Greenland, compared to the present day. The authors caution that the impacts of climate geoengineering cannot be assessed with complete confidence at present.

doi: 10.1038/s41561-018-0249-7


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