In this aerial image, retreated Columbia Glacier is seen on June 24, 2017 in Valdez, Alaska, United States. The tidal glacier retreated 29 kilometres in the past 30 years.

The Asahi Shimbun via Getty





Glaciers are slow-moving rivers of ice that usually grow in winter and shrink in summer.

But with global temperatures rising, many glaciers are losing more ice than they're gaining, meaning the world's glaciers are shrinking.

Philippus Wester, a chief scientist at the International Centre for Integrated Mountain Development, called it "the climate crisis you haven't heard of."

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It's no longer unimaginable to have a world without glaciers.

In September, the Intergovernmental Panel on Climate Change released a report that said around the world, glaciers are losing hundreds of billions of tons of ice every year.

The report's scientists said if humans don't get carbon emissions under control, glaciers would continue to decline, causing "landslides, avalanches, rockfalls, and floods."

Another report found that a third of the icecaps in the Himalayas, which run from Afghanistan to Myanmar, were doomed.

The report's leader, scientist Philippus Wester, called it "the climate crisis you haven't heard of."

These 40 photos show glaciers that are disappearing or on the brink of collapse around the world.

The last remnants of the ice age, glaciers are huge masses of ice that move over land. There are two types: The first is alpine glaciers, which are found on mountains in every continent, except Australia, and the second is ice sheets, which cover places like Greenland and Antarctica.

Wolfgang Kaehler/LightRocket via Getty

Sources: National Geographic, NOAA







According to Antarctic Glaciers, a group that explains glacier science, about 198,000 glaciers cover 450,000 square miles across the globe. Glacial ice covers 10% of the land area on Earth.

Antarctic Glaciers

Sources: Antarctic Glaciers, National Snow and Ice Data Center







Glaciers form from snow falling and piling up. If it doesn't melt, but instead compresses until it becomes hard and granular. This hardened snow is called "firn." As more and more snow falls, it gets even more compact. After years of snowfall, when it gets to about 160 feet, the firn fuses and becomes a block of ice.

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Joe Raedle/Getty

Source: National Geographic







At this point, the glacier can begin to move, helped along by meltwater underneath. But the whole mass doesn't slide at a uniform speed, causing cracks known as crevasses.

DeAgostini/Getty

Source: National Geographic







Scientists began monitoring glaciers over 100 years ago, and formed the International Commission of Snow and Ice in 1894. While scientists have inventoried more than 100,000 glaciers, they've only been studying about 40 of them long enough to do climate change studies.

Joe Raedle/Getty

Sources: NOAA, NSIDC







Mauri Pelto, a glaciologist and the US representative for world glacier monitoring, has been studying glaciers for 36 years. He told Business Insider a lot has changed in that time — 20 years ago it was barely a news topic. But melting has accelerated.

Manuel Valdes / AP





Glaciers made international headlines in September 2019, when a 250,000-cubic-meter chunk of ice from Planpincieux Glacier on Mont Blanc threatened the Italian town of Courmeyeur at its base.

Yara Nardi / Reuters

Source: The Guardian, The Independent







The glacier is 512 square miles. While no homes, or people, were in danger, the local mayor was forced to close a road. If it had collapsed, it would have hit the valley in 80 seconds.

Yara Nardi / Reuters

Sources: The Guardian, The Independent







Italian leader Giuseppe Conte said the rapidly melting glacier was "an alarm" that could no longer be ignored. It helped that the glacier's threat was publicized during the UN general assembly in New York.

REUTERS/Alessandro Bianchi

Source: CBS News







According to World Heritage, glaciers are more than passive climate indicators. They're an essential part of ecosystems, and play a role in the global climate and sea levels.

Sean Gallup / Getty

Source: World Heritage Glaciers







And it's pretty clear that they're melting. An Environmental Protection Agency graph shows the trend of glacier mass between 1945 and 2015.

EPA





Pelto said the easiest way to explain whether a glacier had a future was to see if it had any "income." If a glacier doesn't retain any snow on top of it at the end of the summer, it'll disappear. "You don't look at how fast it's retreating, you ask, 'did it retain any snowpack'," he said.

Fabrice Coffrini / AFP / Getty





He told Business Insider, "I've watched five glaciers that I visited annually disappear, and that's not even the most alarming thing." It was the number of new alpine lakes that he found to be the most concerning.

Sean Gallup / Getty





According to USGS scientist Caitlyn Florentine, who studies glaciers in North America, the first glaciers to go will be the small ones at low elevations, or in regions where snowfall becomes rain in the near future, due to a warming climate.

Sergi Reboredo/VW PICS/Universal Images Group via Getty





Florentine said one of the best ways to understand the vulnerability of disappearing glaciers is to look at the effects of their melting. There are three main prongs — the ecological consequences, the increase in global sea levels, and the impact on water resources.

Sean Gallup / Getty





An ecological consequence, for example, could be the effect glacial melt could have on salmon populations. Here, fisherman in Alaska try to catch silver salmon with the Knik glacier out in front of them.

Al Grillo / AP





Glacial melt could impact salmon populations, because salmon breed in certain temperatures. If glaciers have melted, there will be no more icy water, resulting in streams getting warmer, which could harm their breeding patterns.

Andrew Burton / Getty

Source: The New York Times







As glaciers melt, sea levels rise. A study published in Nature in April found that glacier melt is already responsible for 30% of sea level rise. West Antarctica has some of the most threatening glaciers for rising sea levels.

REUTERS/NASA/GSFC/Jefferson Beck/Handout

Source: Quartz







One particularly large glacier called Pine Island Glacier made headlines in 2017, when it lost a chunk of ice four times the size of Manhattan. Scientists estimate that if it melts, global seas could rise by 1.7 feet.

Universal History Archive / Universal Images Group / Getty

Sources: Business Insider, Washington Post







In February, a hole 6 miles long and 1,000 feet deep was discovered under Thwaites Glacier, another large Antarctic glacier, which is the same size as Florida. The hole is the equivalent to losing about 14 billion tons of ice, and showed that the glacier was being hollowed out by water, as well as shrinking.

NASA

Sources: Business Insider, NBC News







It's also receding by 2,625 feet every year. Scientists estimate Thwaites could collapse within the next 100 years. When it does, sea levels around the world could rise by two feet.

James Yungel/NASA via Wikimedia Commons

Sources: Business Insider, NBC News







Florentine said the melting could have repercussions on the land and rivers below the Himalayas, for example, where communities rely on glaciers' annual melt for crops and drinking water.

Halldor Kolbeins / AFP / Getty





In early 2019, The Hindu Kush Himalaya Assessment, which 200 scientists worked on for five years, found that a third of Himalaya's glaciers, also known as "the third pole," were doomed, regardless of what was done to stop climate change.

Prakash Mathema / AFP / Getty

Sources: The Guardian, The Diplomat, The Hindu Kush Himalaya Assessment







If emissions aren't cut, the report said two-thirds of the Himalayan glaciers could be lost. It's an important area, since it holds the third-most ice in the world after Antarctica and the Arctic.

Ed Giles / Getty

Source: The Guardian







These glaciers provide water for 250 million people who live near the mountains. Further out, another billion people rely on the rivers that flow from these mountains. When the report was released, Philippus Wester, the report's leader, called it "the climate crisis you haven't heard of."

Pool /Samir Hussein/WireImage / Getty

Source: The Guardian







The report said that after an initial melt and increase in water flow, possibly leading to high-altitude lakes bursting, water supplies would dry up. Communities that relied on power from hydro-dams, or farmers who relied on water for crops, would suffer. It'll be especially difficult as glaciers melt in the summer when water is in the highest demand.

Aamir Gureshi / AFP / Getty

Source: The Guardian







It's not just glaciers in Antarctica and the Himalayas that are in danger of disappearing. A study published in Nature in April looked at 19,000 glaciers and concluded almost all of them were melting. The glaciers shrinking the fastest were in the US, Western Canada, central Europe, New Zealand, and the Caucasus region.

Education Images / Universal Images Group / Getty

Source: Quartz







In Europe, Austria's glaciers might not be around much longer. According to scientist Andrea Fischer, who conducts Intergovernmental Panel on Climate Change research, Austria's glaciers have been disappearing faster than most.

Sean Gallup / Getty

Source: Yahoo News







Pasterze Glacier, the country's largest, has been thinning by about 3 feet every year. Glaciologist Anton Neureiter told DW he didn't even need his equipment to notice the melt.

Sean Gallup / Getty

Source: DW







"It's so tangible. You can see the changes from year to year, even month to month, every time you visit the glacier," Neureiter told DW. "This glacier is dying. It's falling apart."

Sean Gallup/Getty

Source: DW







Greenland's Helheim Glacier, named after Norse mythology's realm of the dead, is as tall as the Statue of Liberty. It's losing tens of meters of ice every day. In 2017, the glacier lost two miles of ice.

Lucas Jackson / Reuters

Source: CNN







But it's still so large, the AP's Seth Borenstein wrote, that the only way to get any idea of its scale is by seeing a helicopter dwarfed by the icy landscape.

Felipe Dana / AP

Source: Los Angeles Times







In Greenland, Eqip Sermia Glacier loses ice from calving every year, which is not unusual, but it's also retreated nearly 2 miles over the last century.

Sean Gallup / Getty

Source: The Atlantic







In Kazakhstan, above the city of Almaty, the Tuyuksu Glacier, which is about 1.5 miles long, is "melting like mad", The New York Times reported in January 2019. It's lost over half a mile, or a third of itself, in 60 years.

Roustem Nurmambetov / Youtube

Source: The New York Times







In China, the Laohugou Glacier had all of its tourism facilities removed in 2017, because it had sunk by 1,300 feet in the last 60 years.

Xinhua / Chen Bin / Getty

Source: Xinhua Net







Elsewhere in China, scientists say the Baishui Glacier, on the Jade Dragon Snow Mountain, is one of the fastest melting glaciers in the world, due to climate change and the mountain's location near the equator. It's lost 60% of its mass and shrunk by 820 feet since 1982.

Sam McNeil / AP

Source: The Japan Times







In Canada, massive glaciers on the Saint Elias mountains, which go across Yukon, Alaska, and British Columbia, are losing ice faster than anywhere else in the country. Between 1957 and 2007, the range lost 22% of its ice.

Matthew Bailey / VWPics / Universal Images Group / Getty

Source: The Guardian







If things continue the way they're going, smaller glaciers in warmer locations will struggle to make it to the end of the century, Pelto told Business Insider. "The actual science is depressing. The results do get to you emotionally."

MyLoupe / Universal Images Group / Getty





But he also said the problem was getting a lot more attention. "If you look back to the 1980s, you could tell the names of every scientist, but now there are so many. And that's been uplifting, training the next generation of scientists."

Smith Collection/Gado/Getty





Pelto said he still had hope. "Glaciers are bigger than people think, and they're really slow to get rid of."

Joe Raedle / Getty



