Climate change will affect global water availability through compounding changes in seasonal precipitation and evaporation

Goutam Konapala,Yoshihide Wada,Ashok K Mishra,Michael E Mann

doi:10.1038/s41467-020-16757-w

Abstract

Both seasonal and annual mean precipitation and evaporation influence patterns of water availability impacting society and ecosystems. Existing global climate studies rarely consider such patterns from non-parametric statistical standpoint. Here, we employ a non-parametric analysis framework to analyze seasonal hydroclimatic regimes by classifying global land regions into nine regimes using late 20th century precipitation means and seasonality. These regimes are used to assess implications for water availability due to concomitant changes in mean and seasonal precipitation and evaporation changes using CMIP5 model future climate projections. Out of 9 regimes, 4 show increased precipitation variation, while 5 show decreased evaporation variation coupled with increasing mean precipitation and evaporation. Increases in projected seasonal precipitation variation in already highly variable precipitation regimes gives rise to a pattern of “seasonally variable regimes becoming more variable”. Regimes with low seasonality in precipitation, instead, experience increased wet season precipitation.

Highlights

Both seasonal and annual mean precipitation and evaporation influence patterns of water availability impacting society and ecosystems
We first classify the global land regions into distinct hydroclimatic regimes based on annual means and seasonal variations using observed monthly gridded precipitation data from the Global Precipitation Climatology Centre (GPCC) (See “Methods”)[30]
We used apportionment entropy (AE), which provides a descriptive non-parametric measure determining the seasonal variation for data, such as precipitation, that are not Gaussian distributed, as it captures higher-order statistics unlike parametric methods that characterize the data in terms of, e.g., coefficient of variation and standard deviation[3]

Summary

Introduction

Both seasonal and annual mean precipitation and evaporation influence patterns of water availability impacting society and ecosystems. We employ a non-parametric analysis framework to analyze seasonal hydroclimatic regimes by classifying global land regions into nine regimes using late 20th century precipitation means and seasonality. These regimes are used to assess implications for water availability due to concomitant changes in mean and seasonal precipitation and evaporation changes using CMIP5 model future climate projections. Though the combined monthly distribution of precipitation and evaporation have widespread implications for regional hydrology[15,16], crop yield[17,18], and ecology[19,20], few studies have examined the concomitant changes in both annual mean and seasonal variation in these variables. Regimes with low seasonality in precipitation, instead, experience increased wet season precipitation

Methods

Results

Conclusion