Ice-cores from temperate glaciers as paleoclimate archives in a warming world: what we know and what we need to know

Temperate glaciers have traditionally been viewed as unsuitable archives for paleoclimate and environmental reconstruction due to pervasive meltwater percolation and the consequent alteration or disruption of primary atmospheric signals. Yet, in the context of ongoing climate warming, many formerly cold accumulation glacier basins, traditionally targeted for ice-core drilling, are transitioning toward temperate conditions. Exploiting glaciers as sources of past environmental information will therefore increasingly require consideration of temperate glaciers worldwide.

We synthesize more than seven decades of temperate glacier ice-core research, from pioneering efforts in the 1950s to the recent developments. We discuss the physical and chemical mechanisms by which meltwater impacts ice stratigraphy and proxy records, including impurity elution, recrystallization, liquid water redistribution, and the fractionation of water stable isotopes. Through inter-site comparison across climatic regimes (tropical, mid-latitude and high-altitude temperate glaciers), we identify which proxies are most resilient to post-depositional modification and under which conditions meaningful environmental signals can be recovered.

Our results highlight that, while ice cores from temperate glaciers often lack the pristine stratigraphy of cold ice, they can still provide valuable records of climatic and environmental variability, particularly when interpreted in combination with meteorological observations, reanalysis products, and glaciological data.

With cold glaciers becoming increasingly scarce, in particular at low- and mid-latitudes, progress in ice-core science requires a better understanding of temperate ice processes. This contribution provides a reference framework from which future studies can build.