Long-term snow cover trends in Sierra Nevada, Spain (1951–2021)

Despite the importance of the Sierra Nevada snowpack for monitoring climate change, a consistent and spatially distributed picture of long-term trends in snow cover extent and duration across this region is still lacking. In this study, we generate spatiotemporal simulations of snow cover for 1951–2021 using a cellular automata model driven by climate data. These simulations are evaluated against MODIS observations from 2000 to 2020. We perform statistical significance analysis (Mann–Kendall and t-test) for snow cover variables and assess the relative importance of climate drivers in snow cover extent anomalies. Over the past 70 years, temperature rose by 0.84–1.54 °C in this region, whereas precipitation decreased at a rate of –2.3 to –7.5 mm per year, depending on location and elevation. The analysis of the simulated snow cover time series indicates an overall decline in snow cover extent and statistically significant negative trends of –0.6 to –0.15 days per year in areas with a seasonal and consistent winter snowpack (≥2300 m a.s.l.). The area most affected by negative changes is the western Sierra Nevada. Temperature emerges as the dominant driver of snow cover anomalies, with an overall relative importance of 69.3%. This suggests that the ongoing warming of the Sierra Nevada is a major factor explaining the observed decrease in snow cover extent and duration.