Following new insights on the observed extreme heat during the Dust Bowl 3, 6, and with future increases in global heatwave activity likely 14, a comprehensive understanding of what contributed to the Dust Bowl heatwaves is crucial.Ī Observed summer (June–August) maximum daily maximum temperature (TXx) anomalies (relative to 1901–2010) averaged over the central US (box in b), from gridded observations (HadEX2 colour), and 20 Coupled Model Intercomparison Project Phase 5 (CMIP5) historical model simulations (grey line with shading indicating the 10–90th percentile range relative to 1901–2005).
Improved representations of precipitation and temperatures during the Dust Bowl period are simulated when AGCMs 4, 11 and regional models 13 implement realistic historical land-cover changes and dust aerosol forcing. Yet when forced with observed SST anomalies, atmospheric-only general circulation models (AGCMs) tend to underestimate the drought’s spatial extent and magnitude 4, 11, 12. The drought, defined through precipitation and evapotranspiration-based indices 3, emerged during a period of cooler-than-average North Pacific sea surface temperatures (SSTs) and a warmer North Atlantic 4, 6, 7, 8, 9, 10. Instead a strong upper-level atmospheric ridge and land–atmosphere interactions may have allowed for extreme heat to build during the Dust Bowl drought 3, 4, 5, 6. 1a), are unlikely to have resulted from instrumental biases 2, 3. These records, like maximum daily Tmax over the central US (Fig. Many daily maximum and minimum temperature (Tmax, Tmin) records from the 1930s over the continental US still stand as of 2019 1.
This study highlights the potential for the amplification of naturally occurring extreme events like droughts by vegetation feedbacks to create more extreme heatwaves in a warmer world. Model devegetation simulations, that represent the wide-spread exposure of bare soil in the 1930s, suggest human activity fueled stronger and more frequent heatwaves through greater evaporative drying in the warmer months. Here we show, using an atmospheric-only model, that anomalously warm North Atlantic SSTs enhance heatwave activity through an association with drier spring conditions resulting from weaker moisture transport. It remains unresolved to what extent these exceptional heatwaves, hotter than in historically forced coupled climate model simulations, were forced by sea surface temperatures (SSTs) and exacerbated through human-induced deterioration of land cover. The severe drought of the 1930s Dust Bowl decade coincided with record-breaking summer heatwaves that contributed to the socio-economic and ecological disaster over North America’s Great Plains.
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