【気候科学】アジアの氷河の運命を推測する

Limiting global warming to no more than 1.5 degrees Celsius above pre-industrial levels may protect around 65 per cent of the ice stored in glaciers in the high mountains of Asia by the end of the century, reports a study in Nature this week. However, staying below 1.5 degrees of warming is an ambitious goal, and the analysis suggests that up to 65 per cent of mass could be lost under a scenario of continued high rates of greenhouse gas production.

Glaciers in the high mountains of Asia have an important role in the water supply of millions of people living downstream. These glaciers are losing mass and retreating owing to rising temperatures and are warming at rates higher than the global average.

To assess the impacts of the new climate limit on glaciers in the high mountains of Asia, Philip Kraaijenbrink and colleagues combine satellite observations and glacier evolution models under various climate scenarios. Even for the scenario of a successful 2015 Paris Agreement - in which 195 countries agreed to consider limiting global warming to no more than 1.5 degrees - around 35 per cent of glacier mass is predicted to be lost by 2100. Much greater losses are predicted under more extreme climate scenarios, with projected temperature increases of around 3.5 degrees, 4 degrees and 6 degrees, leading to mass losses of approximately 49 per cent, 51 per cent and 65 per cent, respectively. The difference in impact among these scenarios could be the difference between sustaining these glaciers and the resources they provide to mountain communities, or losing the majority of Asia’s glacier ice mass by the end of the century, the authors suggest.