Dramatic transitions or “seesaws” from dry to wet periods can cause greater damage than either event alone to communities across the U.S, ranging from California, to Texas, to South Carolina. For example, a 2017 wet spell in California caused widespread flooding and occurred right after the state’s multi-year (2011-2016) drought, putting additional strains on the state. A study accepted for publication in Geophysical Research Letters, funded in part by CPO’s Climate Observations and Monitoring program, shows that while the overall global occurrence of dry-wet spell seesaws is small, they have become more frequent over the past 30 years in some parts of the world. The study used satellite-gauge combined estimates of precipitation and other meteorological variables in combination with hydrological modeling as well as new statistical methods to examine how often wet periods have followed droughts over the past seven decades. The authors found that though only about 11% of droughts have been followed by at least one wet spell the following season, the midlatitudes in particular are a regional hotspot and have experienced an increase in the frequency of droughts, wet spells, and dry-wet spell seesaws. They emphasize that the novel statistical framework applied in this study, which includes threshold considerations, should be tailored to a specific sector with defined impacts. Better understanding of these often overlooked but important dry-wet spell seesaws in the context of climate change is a critical first step to advancing potential adaptation strategies.
New research highlights important risk of rapid drought to wet period transitions
