It’s difficult to forget standing in front of a glacier that is advancing towards you, towering ice pillars constantly cracking as they inch forward. The motion is too slow to see in real time, but obvious from one day to the next.

One of us (Harold) experienced this during fieldwork in 2012 at Nathorstbreen on the Arctic archipelago of Svalbard, which was moving forwards more than 10 metres per day.

Encounters like this are rare. Most of the world’s glaciers are retreating rapidly as the climate warms, and thousands are likely to disappear altogether within the next few decades.

However, a small fraction of glaciers do the opposite, and repeatedly speed up and advance for months or years after a long period of stagnation and retreat. This is known as glacier surging, and it has long puzzled scientists.

It might be tempting to view advancing ice as an antidote to the gloomy picture of disappearing glaciers, but the polar opposite is true. Surges can accelerate ice loss, make glaciers more vulnerable to climate change, and create serious hazards for people living downstream of them.

We have just published a global study of over 3,000 surging glaciers to find out what’s causing them to move like this. Our work also........

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