Central Asian compound flooding in 2024 contributed by climate warming and interannual variability

Extensive flooding swept across large areas of Central Asia mainly over Kazakhstan and southwestern Russia from late March to April 2024. It is reported to be the worst flooding in the area in the past 70 years and has caused widespread devastation to society and infrastructure. However, the drivers of this record-breaking flood remain unexplored. Here, we show that the record-breaking floods were contributed by both long-term climate warming and interannual variability, with multiple climatic drivers at play across the synoptic to seasonal timescales. First, the heavy snowmelt in March 2024 was associated with the above-normal preceding winter snow accumulation. Second, extreme rainfall was record-high during March 2024, in line with its increasing trend under climate warming. Third, the snowmelt and extreme rainfall in March were compounded with the record-high soil moisture conditions in the preceding winter, which was a result of interannual variability and was related to excessive winter rainfall over Central Asia. As climate warming continues, the interplay between the increasing trend of extreme rainfall, interannual variations in soil moisture pre-conditions, as well as shifting timing and magnitudes of spring snowmelt, will further increase and complicate spring flooding risks. This is a growing and widespread challenge for the mid- to high-latitude regions.