As Greenland’s glaciers melt, water usually drains to the bedrock below before flowing out to the ocean. But in 2014, a huge torrent of meltwater from a subglacial lake burst out of the surface of the Greenland ice sheet, leaving 25-metre mounds of ice and giant crevasses in its wake.

“We haven’t observed anything like this before,” says at Lancaster University in the UK. “We know that lakes beneath Greenland drain. But what we’ve never seen before is this fracturing and the water actually erupting through the surface of the ice sheet.”

McMillan and his colleagues began to investigate after spotting the sudden appearance of a crater 85 metres deep in the surface of the ice sheet, captured by satellite in August 2014. They used satellite data and numerical models to reconstruct what happened to cause the crater.

They found the crater had emerged after the rapid draining of a subglacial lake within a 10-day period in July and August 2014. About 1 kilometre downstream from the crater, the team spotted a huge disturbance of the ice where the water had emerged.

The team believes the water pressure in the subglacial lake had increased enough to force it back above ground through fractures in the ice, eventually bursting out of the ice sheet and leaving huge crevasses and ice towers in its path.

The meltwater was forced upward because it was surrounded by ice frozen to the bedrock, explains McMillan. “What seems to have happened here is that when you put water into a situation where the ice was kind of frozen in the surrounding region, you could actually build up a lot more pressure, and you could cause this unexpected effect,” he says.

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McMillan now wants to identify whether similar eruptions have happened using satellite imagery, and whether this is a process driven by the ice sheet rapidly melting as global temperatures increase.

“This is a first view of a new phenomenon that we didn’t know existed before, and the challenge now is to understand the implications and the processes of that,” he says.

These striking images highlight Earth’s vanishing ice and the fight to save it. A staggering two-thirds of glaciers may disappear by the end of the century, threatening ecosystems and global water supplies. The images took some of the top prizes in the , run by UNESCO and Onewater. UNESCO has designated 2025 as the International Year of Glacier Preservation.

Julia Roger-Veyer received second place in the European category for her atmospheric shots of the Mer de Glace, France’s largest glacier, at Chamonix. The image above was shot from within a moulin, a huge hole carved into the glacier by meltwater, while the photo below peers inside a cave created by glacial retreat. Roger-Veyer climbs and photographs the Mer de Glace each autumn. Each year, the glacier retreats roughly 40 metres. In an announcement about her win, she said she expects she will “probably be a helpless witness” to its disappearance.

Michele Lapini captured first prize in the Europe category for his shot documenting the effort to save Presena Glacier in northern Italy (below). Vital to the alpine ecosystem, the glacier’s surface area decreased from 68 hectares to 41 between 1993 and 2003, according to Lapini.

In 2008, conservationists began spreading textile sheets over the glacier each summer to prevent melt. The photo shows a worker unhooking sheets during autumn before the first snow. The effort may have by two-thirds, but cannot pause ice loss. As Lapini writes, “climate change cannot be mitigated through localized quick fixes alone”.

The contest’s global prize is sponsored by MPB, its regional Asia prize is sponsored by Asian Development Bank, and its regional European prize by the city of Burghausen.

The first explorers known to have reached the North Pole spent weeks dragging their sleds across the rough pack ice. Now, people can travel most of the way there from the comfort of a cruise ship, their passage eased by the catastrophic melting of ice caused by climate change.

The Arctic is shedding ice at a rate of 12 per cent per decade and is set to be ice-free in the summer by the 2030s – regardless of how fast we cut emissions from now on. Meanwhile, in Antarctica, the vast Thwaites glacier is cracking under the pressure of global warming, and Antarctic sea ice has been tracking at record lows in 2024 for the second year running.

We must cut emissions, and fast, but that alone won’t be enough to stop the runaway melt in the Arctic. To buy us time and to buttress this delicate habitat from a warming world, geoengineering is probably our only hope.

One solution comes from start-up Real Ice, which plans to use seawater to thicken the Arctic’s ice. It is controversial. Geoengineering of this sort, opponents argue, risks distracting humanity from the gargantuan task of cutting emissions.

Of all our geoengineering options, refreezing the poles is perhaps the most benign

Yet there are good reasons to push ahead. Alongside the spectacular wildlife and rich cultural heritage there, the polar regions do the world a huge favour. Their white caps reflect solar radiation back into space, helping to keep Earth’s climate cool. The loss of Arctic sea ice also triggers a whole host of other feedbacks that would amplify climate change and play havoc with weather systems around the world.

Of all our geoengineering options, refreezing the poles is perhaps the most benign. There are, of course, risks. Thorough impact assessments will be vital to minimise any harmful effects on wildlife, local communities or wider Earth systems. But without action, the ice will disappear, destabilising the global climate.

Cuts to greenhouse gas emissions should have started decades ago. The delay has left us with no time to be squeamish about geoengineering.