Projected increases in magnitude and socioeconomic exposure of global droughts in 1.5 and 2 °C warmer climates

Abstract

Abstract. The Paris Agreement sets a long-term temperature goal to hold global warming to well below 2.0 ∘C and strives to limit it to 1.5 ∘C above preindustrial levels. Droughts with either intense severity or a long persistence could both lead to substantial impacts such as infrastructure failure and ecosystem vulnerability, and they are projected to occur more frequently and trigger intensified socioeconomic consequences with global warming. However, existing assessments targeting global droughts under 1.5 and 2.0 ∘C warming levels usually neglect the multifaceted nature of droughts and might underestimate potential risks. This study, within a bivariate framework, quantifies the change in global drought conditions and corresponding socioeconomic exposures for additional 1.5 and 2.0 ∘C warming trajectories. The drought characteristics are identified using the Standardized Precipitation Evapotranspiration Index (SPEI) combined with the run theory, with the climate scenarios projected by 13 Coupled Model Inter-comparison Project Phase 5 (CMIP5) global climate models (GCMs) under three representative concentration pathways (RCP 2.6, RCP4.5 and RCP8.5). The copula functions and the most likely realization are incorporated to model the joint distribution of drought severity and duration, and changes in the bivariate return period with global warming are evaluated. Finally, the drought exposures of populations and regional gross domestic product (GDP) under different shared socioeconomic pathways (SSPs) are investigated globally. The results show that within the bivariate framework, the historical 50-year droughts may double across 58 % of global landmasses in a 1.5 ∘C warmer world, while when the warming climbs up to 2.0 ∘C, an additional 9 % of world landmasses would be exposed to such catastrophic drought deteriorations. More than 75 (73) countries' populations (GDP) will be completely affected by increasing drought risks under the 1.5 ∘C warming, while an extra 0.5 ∘C warming will further lead to an additional 17 countries suffering from a nearly unbearable situation. Our results demonstrate that limiting global warming to 1.5 ∘C, compared with 2 ∘C warming, can perceptibly mitigate the drought impacts over major regions of the world.

Diverging hydrological drought traits over Europe with global warming

“…The combined effects of increasing temperature and decreasing summer precipitation will result in a further exacerbation of water deficits in an area already prone to limited water resources. This is in agreement with global studies that identify the Mediterranean as a hot spot for climate change, even if the targets set by the Paris agreement will be met (Gu et al, 2020), as well as with the potential occurrence of mega droughts in major Iberian water resource regions (Guerreiro et al, 2017).…”

Diverging hydrological drought traits over Europe with global warming

“…Samaniego et al, 2018) and meteorological (e.g. Gudmundsson and Seneviratne, 2016;Spinoni et al, 2018) droughts. Hence, there is growing consensus in the community on the main patterns of climate-induced changes on drought conditions in Europe.…”

Global Characterization of the Varying Responses of the Standardized Precipitation Evapotranspiration Index to Atmospheric Evaporative Demand

“…In the past decade, SPEI has been one of the most widely used drought metrics worldwide. It has been used for different applications, including drought risk assessment (e.g., Blauhut et al, 2015; Domínguez‐Castro et al, 2019), analysis of drought evolution (e.g., Chen & Sun, 2015; Spinoni et al, 2014; Spinoni, Barbosa, Bucchignani, et al, 2019), assessment of drought impacts in different socioeconomic (e.g., Bachmair et al, 2015, 2016; Gu et al, 2020; Leng & Hall, 2019; Ribeiro et al, 2019; Von Uexkull et al, 2016; Zampieri et al, 2017), hydrological (e.g., Barker et al, 2016; Peña‐Gallardo et al, 2019) and environmental systems (e.g., Babst et al, 2019; Bachmair et al, 2018; Fang et al, 2019; Knapp et al, 2015; Mitchell et al, 2014; Slette et al, 2019; Zimmermann et al, 2015), and characterization of drought in future scenarios (e.g., Chen & Sun, 2017; Dewes et al, 2017; Gu et al, 2020; Naumann et al, 2018; Spinoni, Barbosa, De Jager, et al, 2019).…”