Climate variability of glacierized areas under contrasted climate conditions over the last 60 years

Mountains are specific systems, very sensitive to climate change. Most mountain glaciers around the world are shrinking, which is often associated with global warming over the last decades. Identifying the impact of climate changes on mountain glaciers and possible consequences on surrounding ecosystems and biodiversity is a prerequisite to better enhance adaptation and mitigation capacities at local and regional scales. The overall objective of the study is to investigate the climatic variability on annual and seasonal time scales during the last decades. Trends and breakpoints in time-series are analyzed in rainfall, solar irradiance, maximum and minimum temperature, and potential evapotranspiration in twenty-one contrasting locations situated in temperate zones (in the European Alps, the Pyrenees), in the Andean tropical and subtropical zones (Ecuador, Bolivia, Venezuela, Colombia, Peru), tropical Southeast Asia (Indonesia), equatorial Africa (Rwenzori) and, arid and high latitude zones (Argentina). We analyzed how the trends are associated with cloud cover properties (e.g., mean cloud amount, mean cloud pressure, radiatively-weighted average cloud visible optical thickness, and mean cloud temperature) and various climate variability indices: the Atlantic multi-decadal oscillation (AMO), El Niño Southern Oscillation (ENSO), Pacific Decal Oscillation (PDO), the Equatorial Southern Oscillation Index (SOI), and the North Atlantic Oscillation (NAO). Within this work, we used high resolution gridded datasets: Terraclimate (Monthly Climate and Climatic Water Balance for Global Terrestrial Surfaces), CHIRPS (Climate Hazards Group InfraRed Precipitation with Stations), MSWEP (Multi-Source Weighted-Ensemble Precipitation), regional simulations from 12 models provided by the Coordinated Regional Climate Downscaling Experiment (CORDEX), and the Cloud_cci Along-Track Scanning Radiometer and Advanced data set. Long-term (i.e. 1958-2020) significant trends of increased (decreased) annual and seasonal Tmax were identified over all European, Andean, Indonesian, and African glaciers. Over the Argentinian glaciers, long-term trend analysis shows a non-significant increasing trend in Tmax. Over all glaciers, long-term trend analysis shows a significant increasing trend in Tmin. Long-term significant trends of decreased annual rainfall were identified over African and most Alps and Pyrenees glaciers. On the other hand, no significant trends of rainfall were identified over the other glaciers. European glaciers were more influenced by the cloud cover properties than the tropical glaciers, with negative correlations between mean cloud amount and Tmax and solar irradiance. AMO plays a greater role than ENSO and PDO in causing climatological changes on glaciers in temperate and African zones. While the Bolivian and Argentinian glaciers were the least influenced by AMO and NAO, most of the glaciers in Ecuador and Colombia were the most influenced by SOI. These preliminary results highlight strong regional contrasts in climate variability (and its response to the influence of large-scale climatic variability patterns) between the different regions of the world.