Changes in drought occurrence due to climate change in Norway

Due to climate change, droughts are becoming more frequent and severe in many parts of the world. The drought experienced in Norway during 2018 caused significant repercussions, particularly in the agricultural industry. Norway's rising temperatures and altered precipitation patterns are attributed to climate change. While annual precipitation has increased and precipitation events have become more intense, summer precipitation is not expected to increase everywhere in Norway, and evaporation will rise with temperatures. The impact of these changes on the risk of drought in different regions of Norway remains uncertain.

To address this uncertainty, we undertook an analysis of the frequency, extent, and duration of summer (April-September) drought in Norway, utilizing several meteorological drought indices such as the Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI) at timescales ranging from 3 to 12 months. We have developed monthly gridded datasets of SPI and SPEI based on gridded daily precipitation and potential evapotranspiration. The potential evapotranspiration is estimated by the Penman-Monteith formula. Using these datasets, we calculated trends and compared the last two official normal periods (1991-2020 and 1961-1990) to analyze historical changes. Furthermore, we compared future climate projections with the 1991-2020 period to identify potential future changes. 

Preliminary results did not indicate significant changes in occurrence of severe droughts in Norway. The two drought indices applied shows the same temporal variability, and the increase of total summer precipitation balances the increased potential evapotranspiration.  There is however a slight increase in the SPEI drought conditions compared to SPI. 

Our research has implications for Norway's agricultural sector and natural resource management. A better understanding of past and future drought changes can aid in the development of effective adaptation strategies.