The impact of climate mitigation on projections of future drought

Abstract

Abstract. Drought is a cumulative event, often difficult to define and involving wide-reaching consequences for agriculture, ecosystems, water availability, and society. Understanding how the occurrence of drought may change in the future and which sources of uncertainty are dominant can inform appropriate decisions to guide drought impacts assessments. Our study considers both climate model uncertainty associated with future climate projections, and future emissions of greenhouse gases (future scenario uncertainty). Four drought indices (the Standardised Precipitation Index (SPI), Soil Moisture Anomaly (SMA), the Palmer Drought Severity Index (PDSI) and the Standardised Runoff Index (SRI)) are calculated for the A1B and RCP2.6 future emissions scenarios using monthly model output from a 57-member perturbed parameter ensemble of climate simulations of the HadCM3C Earth System model, for the baseline period , and the period 2070-2099 ("the 2080s"). We consider where there are statistically significant increases or decreases in the proportion of time spent in drought in the 2080s compared to the baseline. Despite the large range of uncertainty in drought projections for many regions, projections for some regions have a clear signal, with uncertainty associated with the magnitude of change rather than direction. For instance, a significant increase in time spent in drought is generally projected for the Amazon, Central America and South Africa whilst projections for northern India consistently show significant decreases in time spent in drought. Whilst the patterns of changes in future drought were similar between scenarios, climate mitigation, represented by the RCP2.6 scenario, tended to reduce future changes in drought. In general, climate mitigation reduced the area over which there was a significant increase in drought but had little impact on the area over which there was a significant decrease in time spent in drought.

Global warming and 21st century drying

“…PDSI has persistence on the order of 12-18 months (Guttman 1998;Vicente-Serrano et al 2010), integrating moisture gains and losses throughout the calendar year, and providing a useful metric to describe longer term trends and variability in hydroclimate. PDSI has been widely used as a metric to quantify drought using climate model simulations (e.g., Bonsal et al 2013;Burke and Brown 2008;Coats et al 2013;Cook et al 2010Cook et al , 2013Dai , 2013Rosenzweig and Hillel 1993;Seager et al 2008;Taylor et al 2013). …”

Recent Patterns in Climate, Vegetation, and Forest Water Use in California Montane Watersheds

“…Because SPI only relies on precipitation data, it can only reflect the change in hydrologic input to the system. The addition of SRI is a more complete interpretation of the drought signal here since it integrates other effects [45]. SRI is impacted by evapotranspiration that is also modified by changes in temperature and the surface energy balance.…”

Impacts of climate change on the seasonality of low flows in 134 catchments in the River Rhine basin using an ensemble of bias-corrected regional climate simulations

“…Assessing the impacts of climate change and associated uncertainties of the climate change projections is an important field in hydroclimatology (Arnell and Gosling, 2013;Bennett et al, 2012;Chen et al, 2011;Jung et al, 2013;Minville et al, 2008;Prudhomme and Davies, 2009;Taylor et al, 2013). The assessment of the effect of climate change impacts on hydrological catchment response is based on predicted meteorological variables like precipitation and temperature by climate models.…”