Climate Change

What caused a spike in extreme heat events in Northeast Asia

Extreme heat events have become more likely to occur over Northeast Asia

By DTE Staff
Published: Wednesday 17 June 2020
A record-breaking heat wave had swept Northeast Asia in 2018 Photo: Ren Liwen / Institute of Atmospheric Physics

New research has revealed a link between an increase in extreme summer heat events in Northeast Asia and the role of anticyclones in the region. Extreme heat events have increased across the world and are responsible for a large number of deaths and harming crops and livestock as well.

A record-breaking heat wave had swept Northeast Asia in 2018, resulting in 71,266 hospitalisations for heat strokes in Japan. Similarly, China’s Meteorological Administration was forced to issue high-temperature warnings for 33 consecutive days.

This 2018 heat wave was not a random occurrence, but a part of a larger pattern of air circulation, according to a study published in journal Environmental Research Letters in May 12, 2020.

The 2018 event was used by the study to probe further into what caused such heat events to increase and look into anticyclones as well.

Anticyclones are high atmospheric pressure areas that cause clear skies and high temperatures. They are also responsible for settled weather conditions.

Nearly half of the magnitude of the 2018 extreme heat event was caused by anomalous anticyclones in Northeast Asia, said Ren Liwen, the study’s lead author and a PhD student of the Institute of Atmospheric Physics at the University of Chinese Academy of Sciences.

“Our study — for the first time — gave a quantitative estimation of the contribution of circulation to such a heat event over Northeast Asia by using the flow analogue method,” he said.

Anticyclones similar to those in 2018 became more common and worse in recent decades (1991-2017) than the past (1958-1990), the study pointed out.

Extreme heat events have, thus, become more likely to occur over Northeast Asia: Dynamic (anticyclonic) and thermodynamic (mean temperature shifts to warmer states and increasing greenhouse gases) changes in the atmosphere are the cause for this.

The more extreme the heat event, the larger the contribution of the thermodynamic change will be, said Zhou Tianjun, the study’s co-author.

In some cases, the contribution could be up to 80 per cent, according to Zhou.

“This implies that as long as global warming continues, we would face higher risk of extreme heat events over Northeast Asia in the coming decades,” Zhou said.

The study was jointly supported by the National Key Research and Development Program of China and the National Natural Science Foundation of China and the International Partnership Program of Chinese Academy of Sciences.

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