With the Paris Agreement, the urgency of limiting ongoing anthropogenic climate change has been recognized.More recent discussions have focused on the difference of limiting the increase in global average temperatures below 1.0, 1.5, or 2.0 • C compared to pre-industrial levels. Here, we assess the impacts that such different scenarios would have on both the future evolution of glaciers in the European Alps and the water resources they provide. Our results show that the different temperature targets have important implications for the changes predicted until 2100, and that glaciers might start recovering after the end of the 21st century.
IntroductionClimate change is one of the largest challenges that society will need to face during this century. There is overwhelming consensus that limiting the increase of global average temperatures below a certain threshold is essential if adverse effects are to be avoided (IPCC, 2013). Put forward in 2015 and adopted by 196 parties, the Paris Agreement concurred that such a threshold is "well below 2 • C above pre-industrial levels", and that efforts should be pursued to "limit the temperature increase to 1.5 • C" (UN, 2015). Even under these ambitious targets an important environmental change is to occur. The Special Report on Global Warming of 1.5 • C (IPCC, 2018), for example, focused on the effects that would result if the 1.5 • C target was to be met, and highlighted that even under such conditions, important and mostly negative changes would occur. Five years after the Agreement, there is compelling evidence that any reduction of anthropogenic climate change will pay off in the longer term, both from an ecological (IPBES, 2019) and economical (WEF, 2020) perspective. Discussions in preparation for the renewed pledges by signatory parties have thus focused on the differences between scenarios close to the original targets. For the upcoming 26 th United Nations Climate Change Conference of the Parties, for example, emphasis is put onto separating the impacts occurring under scenarios of 1.0, 1.5, and 2.0 • C of warming above pre-industrial levels. In this brief communication, we focus on the differing impacts that such scenarios would have on glaciers and related water resources in the European Alps.Across the world, glaciers are amongst the most prominent indicators for climatic change, as they show an integrated response of climate forcing over decades to centuries (e.g. Roe et al., 2016). Previous work estimated that every kg of additionally 1