Research press release


Nature Geoscience

Climate science: Spring Arctic ozone depletion alters Northern Hemisphere climate

北極域全体で春季にオゾン減少が繰り返し起きる事象(人類によるオゾン層破壊ガスの放出の結果)は、一時的に北半球の温度と降雨のパターンを変化させる可能性があることを示したけんきゅうが、Nature Geoscience に掲載される。


今回Marina Friedelたちは、過去40年間(1980〜2020年)に得られた大気データを分析し、北極域で顕著なオゾン層の減少が見られた年を特定した。著者たちは、春季に特にオゾン量が少ない期間は、決まってその数週間後に、ヨーロッパ北部では湿潤な条件に、ヨーロッパ南部とユーラシアでは温かく乾燥した条件となることを明らかにした。著者たちは、オゾンの化学的性質を正確に表現した2つの気候モデルを用いて、オゾン減少の効果を、無関係な大気循環過程から抜き出すことができた。オゾン減少は成層圏(地球大気の2番目の層)の冷却をもたらすことが分かった。このように冷却されることで極渦(冷たい北極の空気を南側にもたらす気候現象)の存在が春季まで延長され、北半球に地表温度と降雨の異常を生じさせた。


Recurring springtime ozone depletion events over the Arctic — the result of human emissions of ozone-destroying gases — can temporarily alter Northern Hemisphere temperatures and rainfall patterns, according to a study published in Nature Geoscience.

The ozone layer in the Earth’s atmosphere plays a key role in the absorption of potentially harmful ultraviolet radiation from the Sun. The release of gases such as chlorofluorocarbons has damaged the layer in recent decades, affecting the energy balance of the atmosphere. The persistent ozone hole over Antarctica is known to influence surface conditions in the Southern Hemisphere. However, it is unclear whether there are similar surface climate effects in the Northern Hemisphere.

Marina Friedel and colleagues analysed atmospheric data from the last four decades (1980–2020) to identify years with pronounced depletion of the ozone layer over the Arctic. The authors reveal that intervals of particularly low levels of ozone in the spring are typically followed several weeks later by wetter conditions in northern Europe and warmer, drier conditions in southern Europe and Eurasia. Using two climate models — which include accurate representations of ozone chemistry — the authors were able to disentangle ozone depletion effects from unrelated atmospheric circulation processes. Ozone depletion was found to lead to a cooler stratosphere (the second layer of the Earth’s atmosphere). This cooling, in turn, prolongs the presence of the polar vortex — a climatic phenomenon which can bring cold Arctic air southward — further into the spring which causes surface temperature and rainfall anomalies in the Northern Hemisphere.

The authors conclude that consideration of these ozone feedbacks could substantially help to improve the prediction of Northern Hemisphere climatic conditions in the weeks and months ahead.

doi: 10.1038/s41561-022-00974-7


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