Droughts Immediately Following Heat Waves... New Compound Climate Disaster Spreading Worldwide

Recent research has found that a new form of compound climate disaster-where droughts immediately follow heat waves-has been rapidly increasing worldwide in recent decades. This phenomenon, known as a “heat wave-preceded flash drought,” is attracting attention as a new type of disaster associated with climate change, where a heat wave occurs first and is quickly followed by a severe drought.

The image of Baekgu exhausted by the sweltering heat without any shade.

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A research team led by Professor Sangwook Ye at Ewha Womans University announced these findings in the international journal Science Advances on March 7. According to the study, the frequency of compound disasters (CDHE) in which droughts follow heat waves has increased approximately eightfold since 2000 compared to previous periods.

Flash droughts triggered by heat waves occur due to intensified interactions between the land surface and the atmosphere. When temperatures rise suddenly, the land surface heats up quickly, and this heat is transferred to the atmosphere, further raising air temperatures. During this process, evaporation from soil and vegetation accelerates, reducing the amount of water vapor and clouds in the atmosphere, ultimately leading to drought conditions.

The research team analyzed about 40 years of global climate observation data from 1980 to 2023. They found that compound disasters where a heat wave is followed by drought have shown a sharp, nonlinear upward trend over time. In contrast, compound disasters where drought occurs first and is then followed by a heat wave exhibited a relatively moderate increase.

Intense sunlight is pouring down over the citizens walking in Insadong, Seoul.

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The researchers identified the intensification of land-atmosphere interactions due to global warming as the main cause of this phenomenon. They explained that since the late 1990s, these interactions have become stronger, creating an environment where heat waves are more likely to lead to droughts.

Regionally, this increase in compound disasters was most pronounced in areas such as South America (including the Amazon), North America, Eastern Europe, Central Africa, and South Asia. The research team noted that these regions are particularly affected by changes in land environments and land use.

Kim Yongjun, a researcher at Hanyang University and the lead author of the study, stated, “The early 2000s marked a period when the global average temperature had risen by about 0.6 to 0.7 degrees Celsius compared to pre-industrial times, and it was precisely then that signs of a sharp increase in extreme climate events began to appear.” He added, “Since droughts can intensify rapidly after a heat wave, significant damage could occur if prediction and response systems are not adequately prepared.”

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