Drought-flood alternation under climate change

Climate change is increasing the frequency of both droughts and floods, and that means that back-to-back extreme events are also on the rise. These rapidly alternating crises can harm people in complex ways. For example, back-to-back climate extremes can stress crops, reducing yield. In addition, the ability to prepare for one emergency is likely reduced if people are still recovering from the last emergency. Wei Qi and colleagues used climate projections and hydrological and socioeconomic mapping to investigate the future of three drought–flood switching event types in China: drought–flood alternation events, drought-to-flood transitions, and flood-to-drought transitions. The authors show that all these event types are increasing as the climate warms, with a mean frequency increase of 10.09% per 0.5 °C of warming. The area affected each year by such events is also likely to increase, with the Yangtze Basin and North China Plain consistently emerging as national hotspots. In addition, low-income populations are likely to see the steepest relative increases in exposure to rapid hydrological transitions. According to the authors, the findings show how climate change is likely to be a regressive force, deepening the divide between the resilient wealthy and the vulnerable poor. 

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