アフリカの角におけるホロセンの温度-湿度関係逆転

A J Baxter¹, D Verschuren², F Peterse³

¹Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Utrecht, The Netherlands. A.J.Baxter@uu.nl.

Nature

|August 9, 2023

まとめ

気候変動によりアフリカの角はさらに乾燥する可能性があります過去のデータは温度と湿度の関係が変化したことを示し,温暖化とともに降雨よりも蒸発が増加したことを示しています.

科学分野:

古代気候学
気候モデリング
水学

背景:

人為的な気候変動は,特にモンスーンによる降雨に依存する熱帯地域で,地球規模の水循環に影響します.
近年ではアフリカの角で干ばつが増加しており気候モデルでは温度上昇に伴い降水量が増加すると予測されています
気候変動のパラダイム"乾燥が乾燥し湿気が湿り"は幅広い温度範囲でテストする必要があります

研究の目的:

過去7万5千年の間,アフリカ最東部の水候と気温の関係を調査する.
古気候データを用いて"乾燥して乾燥し湿ったと湿った"のパラダイムをテストする
過去の気候の転換点とその影響が地域における将来の気候変動に及ぼす影響を理解する.

主な方法:

チャラ湖 (ケニアとタンザニア) の堆積物記録からの有機地化学気候プロキシデータの分析.
過去7万5千年の水候と気温の変化を再構築
古気候データと気候モデル予測の比較

主要な成果:

ホロセンの始まり (11,700年前) 頃には,効率的な水分と気温の関係が変化した.
最後の氷河期には,より高い温度と湿度が相関していましたが,この関係はホロセンの初期に否定的になりました.
大気中の二酸化炭素が250ppmを超え,気温が現代の値に近づき,降雨よりも蒸発が好まれるようになった.

結論:

人類による温暖化が続くとアフリカの角では干ばつがさらに増えるでしょう
この研究は熱帯水循環における重要な転換点を強調しています温暖化により降水よりも蒸発が増加します
将来の気候変動の影響を正確に予測するには,熱帯水循環のシミュレーションを改善する必要があります.

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