Biological and Environmental Research - Earth and Environmental System Sciences
Earth and Environmental System Modeling
29 June 2020

Observed Changes in Dry Season Water Availability Attributed to Human-Induced Climate Change

Understanding and attributing changes of water availability.

Science

The changes in dry season water availability were investigated using observation-based water availability reconstructions from data-driven and land surface models and CMIP5 factorial simulations for the period 1902–2014.

Impact

We provided the first clear evidence of a discernible human fingerprint on the global changes in dry season water availability. We highlighted the need for urgent climate action if the observed intensification of the dry season is projected to continue under further global warming.

Summary

Effects on the hydrological cycle and the availability of water resources are among the most important potential impacts of human-induced climate change. However, previous assessments of observed warming-induced changes in dryness are influenced by natural climate variability and show conflicting results due to uncertainties in the response of evapotranspiration. Here we employ novel observation-based water availability reconstructions from data-driven and land surface models from 1902 to 2014; a period during which our planet has experienced global warming of approximately 1°C. The analysis reveals consistent changes in average water availability of the driest month of the year in the recent three decades compared to the first half of the 20th century. The global pattern of changes is extremely likely influenced by human-induced climate change as it is consistent with climate model estimates that account for anthropogenic effects and it is not expected from natural climate variability. There is regional evidence of drier dry seasons predominantly in extratropical latitudes and including Europe, Western North America, Northern Asia, Southern South America, Australia, and Eastern Africa. The intensification of the dry season is generally a consequence of increasing evapotranspiration rather than decreasing precipitation.

Contact
Jiafu Mao
Oak Ridge National Laboratory
Publications
Padron, RS, L Gudmundsson, B Decharme, A Ducharne, DM Lawrence, J Mao, D Peano, G Krinner, H Kim, and SI Seneviratne.  2020.  "Observed changes in dry-season water availability attributed to human-induced climate change."  Nature Geoscience 13: 477-481.  https://doi.org/10.1038/s41561-020-0594-1.