Twenty-First Century Drought Projections in Swedish Catchments

Sammanfattning: Droughts can have far-reaching and devastating effects on all sectors of society and ecology and future changes to drought and flood patterns are uncertain. This uncertainty has led to a lax response from local officials in dealing with mitigation and adaptation, particularly in Sweden. As such, this study focused on providing more localized estimates of future drought trends in Sweden so that policy makers can make informed decisions. To assess impacts to different sectors, the results from ten different climate model simulations between 1961-2100 under different emission scenarios, along with hydrological model simulations, were evaluated throughout Sweden for 50 different catchments using a variety of meteorological and hydrological drought indices. We projected a consistent and significant increase in drought severity, duration, and intensity over the course of the 21st century in many parts of Sweden under both moderate and high emission scenarios (RCP 4.5 and RCP 8.5). However, models were in less agreement on the sign of change of drought frequency. These results are highly consistent with more regional pan-European studies on drought, but also show significant departures due to local catchment-specific variability in some forms of drought. Local impacts to agriculture, energy production, water supply, public health, and fresh-water ecosystems are briefly discussed. These results are likely underestimates of future drought due to biases in the models. Improved formulations of drought indices along with a more robust statistical handling of the model output could reduce these uncertainties.