A recent study has revealed that tropical glaciers in the Andes mountains of Colombia, Peru, and Bolivia have shrunk to their smallest size in over 11,700 years, marking an unprecedented retreat since the onset of the Holocene epoch.

This alarming discovery underscores the impact of rising global temperatures on glacial retreat, particularly in tropical regions where seasonal temperature variations are minimal.

The research, led by Andrew Gorin, a graduate student at the University of California, Berkeley, and published in Science, suggests that these glaciers are likely smaller than they have been in the past 125,000 years. However, the current data lacks the precision to confirm this hypothesis definitively.

Gorin’s study, initiated during his master’s program with Jeremy Shakun at Boston College, employed a novel technique analyzing isotopes beryllium-10 and carbon-14 in bedrock recently exposed by retreating glaciers. These isotopes accumulate in rock surfaces when exposed to cosmic radiation, providing a timeline of glacial coverage.

Surprisingly, the study found no significant presence of these isotopes in the bedrock samples, indicating that the glaciers have not been smaller than their current size since the last Ice Age.

This absence of isotopic “sunburn” suggests the glaciers have consistently covered the bedrock until now, further emphasising the severity of their current retreat.

Jeremy Shakun, a paleoclimatologist and co-author of the study, highlighted that this retreat is primarily driven by rising temperatures rather than changes in snowfall or cloud cover.

The findings indicate that the tropical Andes have already warmed beyond their Holocene range, entering the Anthropocene — a proposed epoch where human activity significantly impacts the planet.

The study’s implications extend beyond the Andes, serving as a “canary in the coal mine” for global glacial retreat. It suggests that glaciers worldwide may be retreating faster than previously anticipated, potentially decades ahead of earlier predictions.

This rapid melting poses significant challenges for water resources, ecosystems, and communities dependent on glacial meltwater.

The team plans to expand their study to include glaciers in southern South America, aiming to provide a comprehensive global perspective on the current state of glacier retreat.