Research press release


Nature Geoscience

Climate change: 1.5 °C target keeps the tropics under human adaptability limit

全球の温暖化を産業革命前と比べて1.5℃までに抑えることで、南緯20度から北緯20度の熱帯赤道地域が、人間の適応能力の限界に達するのを防ぐ可能性があることを示唆する論文がNature Geoscience に掲載される。


Yi Zhangたちは今回、数値モデルシミュレーションと観測結果を解析して、極端な湿球温度が将来の温暖化にどのように応答するかを調べた。その結果、湿球温度の最大値を制御するのは、熱帯では比較的単純な大気力学条件であることが分かった。Zhangたちは、モデル化と観測の結果に基づいて、熱帯の極端な湿球温度は、熱帯の平均気温とほぼ同じ速さで上昇すると示唆している。


Limiting global warming to 1.5 °C could prevent tropical regions between 20°S and 20°N of the equator from reaching the limit of human adaptability, suggests a paper published this week in Nature Geoscience.

Humans’ ability to regulate body heat is dependent on the temperature and humidity of the surrounding air. There exists an upper survival limit, beyond which humans are no longer able to effectively cool themselves. This threshold is reached when the wet-bulb temperature — a measure of air temperature and humidity — passes 35 °C. There is concern that ongoing climate warming could result in extreme heat events that exceed this limit.

Yi Zhang and colleagues analysed numerical model simulations and observations to investigate how wet-bulb temperature extremes are likely to respond to future warming. They find that relatively simple atmospheric dynamics control the maximum wet-bulb temperature in the tropics. Based on their modelling and observations, the authors suggest that wet-bulb temperature extremes in the tropics increase at approximately the same rate as the tropical mean temperature.

These findings suggest that keeping global mean warming below 1.5 °C should ensure that no region in the tropics will experience extreme heat events that exceed the human survival limit. However, the authors indicate further research will be needed as serious health impacts can still occur well below this limit.

doi: 10.1038/s41561-021-00695-3


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