One Thing That Isn't Slow: Glacial Melt!

Ben Marzeian (University of Bremen) has considered the various models looking at world glacial loss for the 2021 and 2050 time period (https://www.theguardian.com/environment/2021/apr/29/world-lose-glacier-ice-climate-targets). The average mass loss for the world's glaciers predicted by the models over this period is, according to Marzeian, 13000 gigatonnes of ice. Strikingly, the best and worst case scenarios, produced figures for glacial melt that differed by less than 20%. This is because 80% of the glacial mass loss is already 'locked in' by emissions produced 2-3 decades ago. Glaciers are described as having 'long memories'! Some people make optimistic noises about the benefits of hitting the Paris Accord target and limiting the average world temperature increase to 1.5 degrees Centigrade. Even if this is achieved (and it seems unlikely?), the world will still lose 10% of its glacier ice. That melt will generate more than 13,000 cubic kilometres of water (more than a drop in the ocean!). The world losses will not, however, be uniform but will vary from location to location. More than 50% of glacial mass will be lost in Europe and North America. Indeed, the European Alps and the Pyranees mountains could completely lose their glaciers. In other parts of the world, glaciers currently regulate the supply of water to important river systems throughout the year. Changes in glacial mass in these areas will result in winter floods, followed by complete drying in the summer. This will put almost 2 billion people (mainly in China and India) permanently at risk of mountain water shortages. There are few happy scenarios here.