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A series of old photos may reveal the future of these Arctic glaciers

The mammoths, the stunning glaciers of Norway’s Svalbard archipelago, close to the North Pole, carry the scars of climate change more than almost anywhere else on the planet.

Over the past three decades, Svalbard has Heats up twice as fast like the rest of the Arctic region and seven times the global average. That is causing the island’s glaciers to melt at an alarming rate, threatening polar bears and other wildlife, and raising sea levels globally.

However, over the long term, predicting how rapidly future warming might cause the ice to recede remains a guess. In Svalbard and elsewhere, most field measurements only began in the mid-20th century, and satellite observations even later.

Now, advances in computing are helping scientists bring the old ice back to life with incredible detail. Using black and white photographs taken during mapping expeditions nearly a century ago, they are creating three-dimensional digital models of how the glaciers look before being kept for current records. and shed light on the ways they have changed over a longer period of time.

One of the largest reconstructions to date, published Wednesday in the journal Nature, points to a troubling conclusion: Svalbard’s glaciers could thin twice as fast this century than in the previous century.

Emily C. Geyman, a PhD student at the California Institute of Technology and lead author of new research. A deeper historical profile, Ms. Geyman said, allows scientists to test how their changing glacier models fit with the past before using them to study the future.

Ward JJ van Pelt, an associate professor at Uppsala University in Sweden, who contributed to the new study, said: “This is a unique opportunity to look back a bit into the past.

The team’s reconstruction of the Svalbard glaciers in 1936 reveals some remarkable details as to how much some ice sheets have shrunk between that time and 2010. The average loss rate is about 1, 1 foot a year.

Across the icy roof of the planet, rapid warming is destroying life and disrupting vast wildlife landscapes. In it latest annual review In the Arctic, the US National Oceanic and Atmospheric Administration found that shrinking sea ice and snow continued to transform the region last year. The collapsing glaciers caused landslides and tsunamis. The thaw of the permafrost, or continuously frozen ground, has destabilized the homes and infrastructure built on it.

Svalbard sits on the edge of the Arctic sea ice during the winter, Dr van Pelt said. Sea ice reflects most of the sunlight hitting it, so when the ice disappears, more solar energy is absorbed by the ocean, heating the water. This is the main reason why Svalbard is warming faster than the rest of the globe.

To reconstruct the archipelago’s past, Ms. Geyman and her co-authors used more than 5,500 aerial images taken by a cartographic project of Norway in 1936 and 1938. Frozen conditions makes flying a challenge and the equipment is simple: a Zeiss camera mounted on a reconnaissance aircraft.

However, the paintings, which are owned and managed by the Norwegian Polar Institute, a government research group, strongly show the drama of the landscape. “I was just fascinated by the pictures,” Ms. Geyman said.

To convert the fuzzy negatives into three-dimensional digital models, Ms. Geyman had to show her computer how to interpret the images. This involves picking out points on different photographs that show the same feature in the landscape – such as a crevice or a channel cut into the ice by meltwater – so that the software can stitch together the images together correctly.

In total, she placed almost 70,000 such points for the photos. It has lost the better part in two years. “I think I’m starting to have to wear these glasses,” she said, pointing to her face, “because I squint so much at the pixelated images on my screen.”

In some places, the white snow in the photos makes it too difficult to determine the terrain, so she estimates to fill in the gaps.

Once they have digitally reconstructed more than 1,500 glaciers across Svalbard, Ms. Geyman and her co-authors compared them with rivers created from more recent images to determine how much ice has melted since then. since the 1930s.

They then used these specifications to predict that the average elevation of the glaciers in Svalbard would decrease by 2.2 to 3 feet a year before 2100, depending on increases in greenhouse gases. atmospheric glass. That is at least 1.9 times higher than the retreat rate that occurred during the 20th century, even in a modest warming scenario in which global temperature increase is limited to 2 degrees Celsius ( 3.6 degrees Fahrenheit) above pre-industrial levels.

Researchers have been creating three-dimensional computer models of individual glaciers for several years now. Erik S. Mannerfelt, a glaciologist at the Swiss university ETH Zurich, who was not involved in the new study, said that it was only recently that an increase in processing capacity led to the regeneration of the mantle over entire regions. and the mountain range becomes possible.

“This is a new era where we can’t look at individual glaciers, but at populations,” he said.

Mr. Mannerfelt is finalizing a separate paper that uses 22,000 photographs taken by Swiss mountaineers between the two world wars to document changes in Switzerland’s glaciers since the early 1930s. It is hoped that other photographic archives may allow similar detailed reconstructions of the ice in the Tierra del Fuego islands of South America and in the Himalayas.

“Since we now begin to know exactly what happened,” said Mannerfelt, “we can make much better predictions for the future.”

https://www.nytimes.com/2022/01/19/climate/svalbard-glacier-melting.html A series of old photos may reveal the future of these Arctic glaciers

Fry Electronics Team

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