Glaciers are a key part of the Earth's system, but their existence is seriously threatened by global warming. As the climate warms, glaciers melt, with far-reaching consequences for our society and the natural environment. Melting glaciers contribute to rising sea levels, affect water supplies for downstream regions, exacerbate natural hazards, negatively impact biodiversity and ecosystems, and also impact tourism.

Glaciers adapt only slowly to changing climate conditions. For this reason, climate change has long-term consequences for sea level rise and water supplies. Simulations of global glacier evolution suggest that even if temperatures were to stabilize at current conditions (about 1.2°C above pre-industrial levels), glaciers would lose 39 % of their mass by 2020, corresponding to a global sea level rise of 113 mm. This already “committed” but not yet fully realized mass loss highlights that Today's glaciers are in a strong imbalance with current climate conditions due to their long reaction time.The imbalance is exacerbated by the fact that atmospheric warming is particularly pronounced at high altitudes and high latitudes, where glaciers are located.

Significant differences are evident when comparing glacier mass loss under different warming target levels. A study based on eight glacier evolution models estimates that achieving the Paris Agreement goal of limiting warming to +1.5 °C above the pre-industrial level would be maintained in the long term (after reaching equilibrium) more than twice as much global ice mass (53 %) compared to a scenario resulting from current policies, which assumes warming of +2.7°C by 2100 (only 24 % of the original mass will remain).

With global temperatures stabilising at Paris Agreement target levels, glaciers are projected to eventually lose 47 % of their global mass (compared to 2020) under the +1.5°C scenario and 63 % under the +2.0°C scenario. These losses would contribute 138 mm and 190 mm, respectively, to global sea level rise. However, with the 2.7°C warming expected based on current policy commitments, Globally, there has been a loss of 76 % of glacier mass, which would correspond to 230 mm of sea level rise.

Research shows that each additional temperature increase of 0.1 °C between the +1.5°C and +3.0°C scenarios results in an additional loss of 2.0 % of global ice mass, representing an additional 6.5 mm of sea level rise from glaciers alone. At higher levels of warming, for example in a 4°C warming world, a loss of 86 % of current mass is projected, with most mid-latitude regions experiencing near-complete deglaciation. A return to pre-industrial temperatures would be required to maintain current global ice mass.

The long response time of glaciers, which can range from decades to centuries, means that the full response of global ice mass to climate stabilization under the most optimistic scenario of +1.5°C may take about a millennium. This long response time indicates that significant mass losses resulting from current climate policies will continue to be felt beyond 2100.

Findings studies They emphasize that strict and immediate climate change mitigation policies are essential to ensure the long-term preservation of glaciers. Spring

The study is published in the journal Science