Gornergletscher (VS) in 1930 and 2022.The world could lose over 40 percent of its total glacier mass and 80 percent of all individual glaciers this century. Depending on how successful efforts to curb the climate crisis are, it could be "only" a quarter. This is reported today in the journal Science by an international research team with participation from the Swiss Federal Institute for Forest, Snow and Landscape Research WSL. The aim is to support discussions on adaptation to climate change, such as those that took place at the recent United Nations Climate Change Conference (COP 27).
The team led by David Rounce of Carnegie Mellon University, USA, has produced new calculations of global glacier loss over the course of this century under different climate scenarios. These show: In a scenario with unchecked investment in fossil fuels, more than 40 percent of the glacier volume will have disappeared by 2100, or more than 80 percent of the number of glaciers.
Even in a low-emission scenario in which the increase in global average temperature is limited to +1.5 ° C above pre-industrial levels, a quarter of the ice volume and almost every second glacier disappears. In the Alps, even in this favorable scenario, less than one-third of the ice can be preserved. Much of the disappearing glaciers are relatively small, but nevertheless their loss can negatively affect local hydrology, glacial hazards, tourism, and cultural values.
The modeling study provides detailed insight into the future evolution of glaciers globally, as well as locally. The authors hope that melting glaciers will spur policymakers to keep maximum temperature change well below the 2.7 degree mark, which is expected to be reached with current pledges from nations. Regions with smaller glaciers, such as the Alps, the South American Andes or the Rocky Mountains will be massively affected by a temperature rise of more than 2 degrees. With an increase of more than 3 degrees, the ice there will disappear almost completely.
Glaciers react with a strong delay to climate changes. They can be considered as very slow flows. A reduction in greenhouse gas emissions therefore does not have an immediate effect on glaciers: Even if no moreCO2 enters the atmosphere from today, it will take between 30 and 100 years for glaciers to stabilize.
The current study describes the response of each of the more than 200,000 glaciers worldwide. It is based on a precise description of the relevant melting processes and detailed data on ice thickness, ice melt since the year 2000, and debris cover of the ice. Thanks to the latest climate scenarios of the IPCC, which suggest different paths for the development of global society, it is shown where climate protection could "save" how much glacier mass and how the loss affects the rise in sea level.
