The warming the world has already experienced could be enough to melt more than a third of the world’s glaciers outside Antarctica and Greenland – regardless of current efforts to reduce emissions.
That is the stark conclusion of a new study, which analyses the lag between global temperature rise and the retreat of glaciers.
The relatively slow response of glaciers to global warming means it will take to the end of the century – and beyond – to see the benefits of mitigation efforts in the coming decades, the study says.
The “baked in” glacier loss from observed warming has largely been overlooked, another scientist tells Carbon Brief, meaning “we really are on course to obliterate many of these mountain landscapes”.
Ice cube
Glaciers are huge rivers of ice that ooze their way over land, powered by gravity and their own sheer weight. They accumulate ice from snowfall and lose it through melting.
As global temperatures have risen, many of the world’s glaciers have already started to shrink and retreat. Continued warming could see many iconic landscapes – from the Canadian Rockies to the Mount Everest region of the Himalayas – lose almost all their glaciers by the end of the century.
But glacier retreat does not happen overnight. So if global temperature rise stopped immediately, how much of the world’s glacier ice could be saved? And for how much is its fate already sealed?
This is what the new study, published in Nature Climate Change, aims to work out.
The study focuses on the lag between rising temperatures and how quickly glaciers adjust. An ice cube makes a suitable metaphor, as three of the authors – Prof Ben Marzeion, Dr Georg Kaser and Dr Fabien Maussion – explain to Carbon Brief over email:
“If you take an ice cube from the fridge – i.e. from one climate – to the kitchen table – i.e. a new climate – it will, finally, but not instantaneously, melt. The time it takes to fully melt the cube depends on: a) the size of the cube; and b) the temperature in your kitchen.”
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