Global Changes in Drought Conditions Under Different Levels of Warming

Abstract

Higher evaporative demands and more frequent and persistent dry spells associated with rising temperatures suggest that drought conditions could worsen in many regions of the world. In this study, we assess how drought conditions may develop across the globe for 1.5, 2, and 3°C warming compared to preindustrial temperatures. Results show that two thirds of global population will experience a progressive increase in drought conditions with warming. For drying areas, drought durations are projected to rise at rapidly increasing rates with warming, averaged globally from 2.0 month/°C below 1.5°C to 4.2 month/°C when approaching 3°C. Drought magnitudes could double for 30% of global landmass under stringent mitigation. If contemporary warming rates continue, water supply‐demand deficits could become fivefold in size for most of Africa, Australia, southern Europe, southern and central states of the United States, Central America, the Caribbean, north‐west China, and parts of Southern America. In approximately 20% of the global land surface, drought magnitude will halve with warming of 1.5°C and higher levels, mainly most land areas north of latitude 55°N, but also parts of South America and Eastern and South‐eastern Asia. A progressive and significant increase in frequency of droughts is projected with warming in the Mediterranean basin, most of Africa, West and Southern Asia, Central America, and Oceania, where droughts are projected to happen 5 to 10 times more frequent even under ambitious mitigation targets and current 100‐year events could occur every two to five years under 3°C of warming.

Vegetation Responses to 2012–2016 Drought in Northern and Southern California

“…Thus, we further suggest these differential trends in dryness for NorCal and SoCal may be caused by the PDO/ENSO-related seesaw of hydroclimatic variability over the Pacific Northwest and Southwest. The climatic drying might be partly attributed to the anthropogenic warming-induced increase of atmospheric evaporative demand (MacDonald et al, 2016;Naumann et al, 2018;Williams et al, 2015). It is consistent with Deitch et al (2017) who reported significantly reduced (increased) precipitation during the past half-century in SoCal (NorCal).…”

Global characterization of hydrological and meteorological droughts under future climate change: The importance of timescales, vegetation‐CO2feedbacks and changes to distribution functions

“…We employed a multimodel ensemble of different monthly climatic and hydrological variables derived from the CMIP5 global climate models (GCMs) under four different representative concentration pathway (RCP) concentration scenarios (2.6, 4.5, 6.0 and 8.5) for the period 2005–2100 (Taylor et al ., ). Assessing drought conditions based on multimodel means is a common procedure in future drought studies (Dai et al ., ; Naumann et al ., ). The following variables were used: (a) precipitation; (b) maximum and minimum air temperatures; (c) relative humidity; (d) incoming short‐wave solar radiation; (e) total column soil moisture; and (f) surface runoff.…”

When Will Current Climate Extremes Affecting Maize Production Become the Norm?

“…This data set has been used in earlier publications to estimate future changes of heat waves (Dosio et al, ) and drought (Naumann et al, ). We also validate the climate simulation for the specific purposes of this study by comparing the HMD and the SPEI mean values and the values characterized by a return period of 10 years computed on the simulation ensemble with respect to the same values computed from the observations (see Figure S4 and Text S4).…”