This image of the Tian Shan range in northwestern China near the border with Kazakhstan and Kyrgyzstan, was captured on 18 November 2016 by the Copernicus Sentinel-2A satellite
The glaciers of the Tian Shan mountain range in northwestern China had lost about a quarter of their ice mass since the 1960s when this image was captured, in November 2016. Source: ESA

Glaciers All Over the World Are Shrinking Fast—See for Yourself

Advances in satellite technology reveal ice masses in Alaska and Asia have lost 4% of their volume in less than a decade.

Glaciers in the Gulf of Alaska and in Asia’s High Mountain region are melting so fast that the changes can be seen from space, with the shrinkage now measured in years rather than decades. 

Just over 4% of the ice volume in these two regions disappeared between 2011 and 2019, according to the first study to monitor large-scale changes in glacier thickness, mass and sea-level contribution. Researchers used radar altimetry technology embedded in a European Space Agency satellite, which they say is the first step toward year-round observation of all of the Earth’s glaciers from space in high resolution. 

Gulf of Alaska Region

Glaciers lost 4.3% of their volume in less than a decade

Source: "Spatially and temporally resolved ice loss in High Mountain Asia and the Gulf of Alaska observed by CryoSat-2 swath altimetry between 2010 and 20192." The Cryosphere

“We’re measuring glaciers in a new way that hasn’t been done before,” said Livia Jakob, co-author of the study and one of the founders of tech startup Earthwave, which processed the data. “And we’ve demonstrated that we can do it in the two most challenging regions, so now we can do the rest.” 

Columbia Glacier, Alaska

The glacier has lost more than half of its total thickness and volume since the 1980s

Note: These are false-color images, snow and ice appear bright cyan

Source: Landsat images via NASA

Glacier melting globally accounted for almost a third of the sea level rise experienced this century, even as they comprised less than 1% of land ice. The shrinking of glaciers is making mountain slopes less stable, resulting in landslides and floods, while the decrease in ice is already and will continue to impact agriculture, hydropower and water quality in some regions. 

Measuring exactly how much and how fast glaciers are melting has been a challenge. The traditional method is to observe them on site, which has worked for accessible glaciers at lower altitudes such as France’s Mer de Glace, possibly one of the most thoroughly-studied ice masses in human history.

But traditional techniques are hard to deploy in remote locales high up in the Himalayas or deep in the Alaskan mountains. Advances in satellite technology over the past decade have allowed scientists to conduct some monitoring from space. These sets of data, though, traditionally focus either on high-resolution or frequent readings. Jakob’s method does both. 

Bering Glacier, Alaska

Source: Sentinel Hub

Radar altimetry had been used in the past to measure ice sheets and very flat terrain. It’s a simple method: the satellite emits a radar wave to a particular point on Earth. As that signal bounces off the surface and back to the satellite, it’s possible to calculate the height of the surface it first struck. 

In recent years, improvements in technology have led to readings with much higher resolution, which encouraged Jakob and her team to test the technology, first on glaciers in South America’s Patagonia region and Iceland. When they proved that radar altimetry worked there, they moved on to the two glacier systems in their current study. The research involved monthly readings of just over half the glaciers in the Gulf of Alaska, and about a third in Asia. It concluded that the decrease in ice mass contributed as much as 0.016 millimeters per year to sea level rise, or 0.16 millimeters per decade on average. 

“It’s important to understand what’s happening to one single glacier,” said Jakob. “But ultimately, if we look at a global scale, we want to know what’s happening to a whole area to get the whole picture.” 

Baird Glacier, Alaska

Source: Sentinel Hub

Researchers found that glaciers at low altitudes and close to the oceans are highly sensitive to seasonal and multi-annual climatic events. The Pacific decadal oscillation, a recurring pattern of rising and falling ocean surface temperatures, has contributed to a substantial increase in temperatures in Alaska since 2014, and to an acceleration of glacial melting. Continental glaciers in the Tibetan Plateau showed almost no seasonal changes, and year-to-year changes were more gradual.

The sort of data being gathered by ESA satellites and interpreted by Jakob and others is essential to feed the complex models that allow scientists to estimate what will happen in the climate of the future. “Ten years ago there was more or less an idea of how an entire area evolved,” said glaciologist Loris Compagno, who co-authored a separate paper earlier this month modeling Alpine glaciers after 2100 under an optimistic warming scenario. “With satellite data we can really say how each glacier evolved in past years, and then we can calibrate our model to know what will happen in the future.” 

Scientists agree that in almost all parts of the world, glaciers will continue retreating in coming decades as the planet warms. Many will disappear regardless of how humanity reins in emissions. If we manage to keep global warming below 2º Celsius compared to pre-industrial times—the target most countries committed to when they signed the Paris Agreement in 2015—only between 724 and 1,484 of the roughly 4,000 glaciers in the Alps today will remain. 

High-Mountain Asia

The region, which includes the Himalayas, has lost 4.2% of ice volume

Source: Spatially and temporally resolved ice loss in High Mountain Asia and the Gulf of Alaska observed by CryoSat-2 swath altimetry between 2010 and 2019, The Cryosphere

Still, the level of warming does matter, Compagno and his colleagues found. Glacier recovery in the Alps was different under scenarios that assume not just a radical cut in emissions over the coming decades, but also the development of technology to capture carbon dioxide from the atmosphere. “When we look at what happens within this century, we always see a line going down, so we expected a line going to zero” after 2100, Compagno said. “But the funny thing was that there’s a bit of a recovery after 2100. It’s really futuristic, but it’s nice to see.” 

“We can decrease our emissions, and in one, two, three or four generations a glacier can grow again,” Compagno said. “It’s nice to know that there can be a recovery. That if we fight for something, it’s not a lost cause.” 

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