Observed and predicted trends in Icelandic snow conditions for the period 1930-2100

This study presents an estimate of historical snow conditions in Iceland and a projection of these conditions, given different emission scenarios. Historical snow conditions were estimated using in situ observations from manned meteorological stations over the period 1930-2021 and by remotely sensed observations from the MODIS instruments over the period 2001-2021. Historical and future climate conditions, as described by each of the 21 general circulation models (GCM) from the 5th iteration of the Coupled Model Intercomparison Project (CMIP5) as contained in the NASA Earth Exchange (NEX) Global Daily Downscaled Projections (GDDP) dataset, were used to simulate snow conditions in Iceland over the period 1950-2100 under the Representative Concentration Pathways (RCP) RCP4.5 and RCP8.5 with the SNOW-17 model. The results show an increase in the average annual snow cover frequency (SCF) over the historical record detected both in the in situ (1930-2021) and remotely sensed data (2001-2021). Average annual snow depth measurements also revealed an increasing trend over the historical record. Simulated snow conditions show a substantial decrease in both snow water equivalent (SWE) and SCF over the period 1950-2100, a trend more pronounced under RCP8.5 as compared to RCP4.5.