Glacier shrinkage driving global changes in downstream systems

TLDR

Glaciers cover about 10 % of land and are shrinking rapidly, producing cascading impacts on downstream systems and leaving distinct signatures on river flow during low‑water periods. The study synthesizes evidence on how glacier shrinkage will alter hydrological regimes, sediment transport, and biogeochemical and contaminant fluxes from rivers to oceans. The authors conduct a synthesis of existing studies to assess glacier shrinkage impacts on hydrology, sediment transport, and biogeochemical and contaminant fluxes. Projected glacier loss will cause the most severe changes in river hydrology and morphology, threatening biodiversity, ecosystem services such as water for agriculture, hydropower, and consumption, and necessitates adaptation and mitigation planning across all affected regions.

Abstract

Glaciers cover ~10% of the Earth’s land surface, but they are shrinking rapidly across most parts of the world, leading to cascading impacts on downstream systems. Glaciers impart unique footprints on river flow at times when other water sources are low. Changes in river hydrology and morphology caused by climate-induced glacier loss are projected to be the greatest of any hydrological system, with major implications for riverine and near-shore marine environments. Here, we synthesize current evidence of how glacier shrinkage will alter hydrological regimes, sediment transport, and biogeochemical and contaminant fluxes from rivers to oceans. This will profoundly influence the natural environment, including many facets of biodiversity, and the ecosystem services that glacier-fed rivers provide to humans, particularly provision of water for agriculture, hydropower, and consumption. We conclude that human society must plan adaptation and mitigation measures for the full breadth of impacts in all affected regions caused by glacier shrinkage.