Anthropogenic Exacerbation in Dry-Hot Probability and Consequential Record-Shattering Droughts in the Middle and Lower Reaches of the Yangtze River

Abstract

In the year 2019, the middle and lower reaches of the Yangtze River (MLRYR) experienced an unprecedented summer-autumn drought (SAD) driven by dry-hot conditions [high near-surface air temperatures (T) and low precipitation (P)], causing substantial agricultural and economic losses. However, the influence of anthropogenic climate change (ACC) on these dry-hot conditions and their impacts on SAD occurrences remains uncertain. Here, both observations and simulations show that an ACC-driven T increase led to the greater likelihood of dry-hot conditions from August to November 1901–2020 in MLRYR. Using the self-calibrating Palmer drought index (scPDSI) to assess SAD severity, we find an increasing likelihood of SAD occurrence (from 33.3% in 1901–2000 to 85.7% in 2001–2020) in MLRYR associated with more frequent dry-hot conditions. Under a business-as-usual scenario, future dry-hot association is projected to be stronger, with exceptional dry-hot conditions to increase by +10% per century. ACC-induced increase in dry-hot conditions would elevate the likelihood of SAD events like the 2019 event from 1.59% (1961–2020) to 17.82% (2041–2100). Therefore, effective measures are needed in MLRYR to adapt to increasing dry-hot conditions and associated SAD occurrences under anthropogenic warming.