Ahead of COP31, the UN publishes a new report on the risk of ice sheet melting associated with exceeding the 1.5°C threshold

Exceeding the +1.5°C global warming threshold above pre-industrial levels, as set by the Paris Agreement, will have consequences for the Earth's cryosphere, including the melting of ice sheets, glaciers and sea ice, as well as permafrost thaw and profound transformations in the polar oceans. It is still possible to mitigate these losses, provided that overshooting the threshold is kept to a minimum. This can be achieved through emissions cuts, combined with large-scale efforts to remove CO₂ from the atmosphere. The planet's glacial systems are, in fact, extremely sensitive even to temporary temperature rises above +1.5°C, the effects of which may persist for centuries or even millennia.

This is the warning issued by the scientific report Overshoot and the Cryosphere: Averting Global Meltdown. Florence Colleoni, a researcher at the Section of Geophysics of the OGS, specialised in the study of polar regions, also contributed to the report's second chapter, which focuses specifically on polar ice sheets.

The report was published alongside another report, titled State of the Cryosphere 2026: The Cost of Overshoot. The two reports are the result of the efforts of more than 80 scientists specialising in polar and mountain regions, from 60 research institutions across 25 countries. Both documents stem from a joint effort by the International Cryosphere Climate Initiative (ICCI) and the United Nations Environment Programme (UNEP).

The scientific insights provided in the reports are of the utmost importance for COP31, the 31st Conference of the Parties of the United Nations Framework Convention on Climate Change (UNFCCC), which begins today, 9 November, in Antalya, Türkiye, and is scheduled to run until 20 November 2026. Florence Colleoni of the OGS will also be present at the conference.

According to the experts, in order to limit the global consequences and damage caused by ice loss in polar and mountain regions, it is vital to keep any overshoot in temperature to a minimum. Temperatures should be brought well below +1.5°C as quickly as possible. Both reports identify concrete and feasible solutions for bringing global temperatures back below the levels reached during the period of temporary exceedance of global warming thresholds (overshoot). Returning to the +1.5°C threshold would not halt sea-level rise, but it would slow it down. It is therefore vital that we continue to adapt our coastal defences, both in the present and for the benefit of future generations.