The research findings published in the journal, Nature Geoscience underline the delicate condition even glaciers at the highest altitudes in the Alps have reached due to climate warming. Within a short period of only two years, the summit plateau of the Corbassière glacier has reached a tipping point, leaving this natural archive unsuitable for reconstructing major aerosol components at least for the recent period covered by the firn part.
High-altitude glaciers are unique natural archives, enabling us to reconstruct past changes in climate and environment. They contain regional information about atmospheric composition, temperature, precipitation, drought events (mineral dust), forest fires, industrial pollutants and vegetation (pollen). Of particular interest are the pre-industrial to industrial aerosol records, which allow the placement of recent human-induced changes into a longer-term perspective. Aerosol particles have a short atmospheric lifetime of about one week and show highest concentrations closest to the sources. High-altitude glacier ice cores facilitate the reconstruction of the regional aerosol signal, which is required to constrain model simulations of global anthropogenic aerosol radiative forcing.
The research group compared the major ion concentration and stable oxygen isotope ratio in water (δ18O) records from two firn cores drilled on Corbassière glacier in 2018 (14.1-m length, GC18) and 2020 (18.1 m, GC20), respectively. Firn is the intermediate stage in the transformation of snow to glacier ice and is porous, whereas glacier ice is nearly impermeable to liquid water.
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