この夏、熱帯地方は記録的な暑さと湿度に見舞われる(Record-breaking heat and humidity predicted for tropics this summer)

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2024-04-22 カリフォルニア大学バークレー校(UCB)

カリフォルニア大学バークレー校の気候科学者による新たな統計分析によると、エルニーニョ現象と気候変動による地球温暖化の相互作用を考慮すると、熱帯地域の今夏は過去最高の気温と湿度を記録する確率が約70%に達すると予測されています。この予測は、インド、アフリカの大部分、中南米、オーストラリア、さらにフロリダ州とテキサス州も含む広範囲に適用されます。この長期予測により、極端な熱波に備え、人々、家畜、作物を守る準備ができると、研究著者の一人であるウィリアム・ブース教授が述べています。

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ENSOの現状から熱帯の年間最大湿球温度を数ヶ月先まで予測する Forecasting Tropical Annual Maximum Wet-Bulb Temperatures Months in Advance From the Current State of ENSO

Yi Zhang, William R. Boos, Isaac Held, Christopher J. Paciorek, Stephan Fueglistaler
Geophysical Research Letters  Published: 05 April 2024
DOI:https://doi.org/10.1029/2023GL106990

この夏、熱帯地方は記録的な暑さと湿度に見舞われる(Record-breaking heat and humidity predicted for tropics this summer)

Abstract

Humid heatwaves, characterized by high temperature and humidity combinations, challenge tropical societies. Extreme wet-bulb temperatures (TW) over tropical land are coupled to the warmest sea surface temperatures by atmospheric convection and wave dynamics. Here, we harness this coupling for seasonal forecasts of the annual maximum of daily maximum TW (TWmax). We develop a multiple linear regression model that explains 80% of variance in tropical mean TWmax and significant regional TWmax variances. The model considers warming trends and El Niño and Southern Oscillation indices. Looking ahead, the strong-to-very-strong El Niño at the end of 2023, with an Oceanic Niño Index of ∼2.0, suggests a 2024 tropical land mean TWmax of 26.2°C (25.9–26.4°C), and a 68% chance (24%–94%) of breaking existing records. This method also predicts regional TWmax in specific areas.

Key Points

  • Tropical wet-bulb temperatures (TW) peak around 5 months after El Niño winters
  • A multiple linear regression model considering the El Niño-Southern Oscillation index and the long-term warming trend effectively explains TWmax variability
  • Our model quantifies the likelihood of strong El Niño and human-induced warming pushing TWmax to record-breaking levels

Plain Language Summary

The heat and humidity in the tropics can be particularly challenging for people to stay comfortable and healthy. This combination of heat and moisture is described using a measure called the wet-bulb temperature (TW). We found that these extremely humid and hot conditions on land can be predicted about 5 months in advance using a physics-based statistical model. The forecast is possible because the peak of El Niño comes before the peak in the warmest sea surface temperatures, which affects the maximum TW on land. This prediction can help tropical societies to better prepare for extreme heat.

1702地球物理及び地球化学
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