NH022-0010
Substantial increase in the frequency, intensity and extent of El Nino driven concurrent droughts with warming
Friday, 11 December 2020
Poster
Jitendra Singh, Washington State University Vancouver, Vancouver, WA, United States, Moetasim Ashfaq, Oak Ridge National Laboratory, Oak Ridge, TN, United States, Christopher B Skinner, University of Massachusetts Lowell, Environmental, Earth and Atmospheric Sciences, Lowell, MA, United States, Weston B Anderson, International Research Institute for Climate and Society, Columbia University, Palisades, NY, United States, Vimal Mishra, Indian Institute of Technology Gandhinagar, Ahmedabad, 382, India and Deepti Singh, Washington State University, School of the Environment, Vancouver, WA, United States
Abstract:
Concurrent climate extremes pose substantial threats to global food security, agricultural markets, reinsurance industries, and the global economy. Here, we examine the risk of concurrent droughts in historical and future climates across the global summer (June-September) monsoon regions, where agricultural production and water availability is heavily dependent on monsoonal precipitation, using the 40-members NCAR CESM Large Ensemble. The probability of concurrent droughts increases by ~25% increase in the future (2071-2100) relative to historical conditions (1971-2000). In addition, concurrent droughts show significantly higher drought area and intensity, with ~70% increase in the probability of widespread droughts in the future climate. Although concurrent droughts become more frequent, larger and intense, exposure of population and crop/pasture areas to concurrent droughts reduces in the future as wetting in South and East Asia and drying in the Americas result in changes in the drought-affected regions. Specifically, the drought frequency substantially increases over Amazon, Central North America, whereas decrease over East Asia, South Asia, East Africa, and Tibetan Plateau during future concurrent droughts.
We also investigate changes in physical drivers of concurrent droughts in the future relative to the historical period. We find that ~65% concurrent droughts in the historical climate is associated with ENSO variability (both El Niño and La Niña) and it increases to ~75% (3 out of 4) in the future. In particular, concurrent droughts associated with El Niño are more intense and affect larger areas relative to concurrent droughts associated with La Niña and non-ENSO drivers. In the future, the frequency of concurrent droughts associated with El Niño are expected to increases by ~35%, associated with an increase in El Niño events. The increase in frequency of concurrent droughts associated with El Niño’s in the future can be explained by strong moisture divergence over several regions and a weakened Walker circulation, suggesting a change in teleconnection strength. Identifying the physical drivers and mechanisms is key to anticipate such events and their impacts, which is important to a broad suite of climate-sensitive concerns in the interconnected socio-economic and physical systems.
