Arctic lakes are disappearing in a surprise climate discovery

Arctic lakes are disappearing in a surprise climate discovery

An aerial view of a large arctic lake, almost completely dried up. Credit: David Swanson/National Park Service

The Arctic is no stranger to loss. As the region warms nearly four times faster than the rest of the world, glaciers are collapsing, wildlife is suffering and habitats continue to disappear at a record rate.

Today, a new threat has emerged: Arctic lakes are drying up, according to a study published in the journal Natural climate change. The study, led by Elizabeth Webb, a postdoctoral researcher in the Department of Biology at the University of Florida, flashes a new warning light on the global climate dashboard.

Webb’s research reveals that over the past 20 years, Arctic lakes have shrunk or dried up completely across the Panarctic, a region spanning northern parts of Canada, Russia, Greenland, Scandinavia and the United States. ‘Alaska. The results offer clues as to why the massive drying out is happening and how the loss can be slowed.

Endangered lakes are the cornerstones of the Arctic ecosystem. They provide an essential source of fresh water for local indigenous communities and industries. Threatened and the threatened speciesincluding Migrator birds and aquatic creatures also depend on lake habitats for their survival.

The decline of the lake is a surprise. Scientists had predicted that climate change would initially expand the lakes across the tundra, due to land surface changes resulting from melting ground ice, with eventual drying up in the mid-21st or 22nd century. Instead, it appears that permafrost thaw, frozen ground that blankets the Arctic, can drain the lakes and outweigh this spreading effect, Webb says. The team hypothesized that thawing permafrost may reduce the surface area of ​​the lake by creating drainage channels and increasing soil erosion in the lakes.

“Our results suggest that permafrost thaw is happening even faster than we as a community anticipated,” Webb said. “It also indicates that the region is likely on the path to landscape-scale drainage in the future.

Arctic lakes are disappearing in a surprise climate discovery

An aerial view of a large arctic lake, almost completely dried up. Credit: David Swanson/National Park Service

In addition to rising temperatures, the study also found that increased fall precipitation causes permafrost degradation and lake drainage. “It may seem counterintuitive that increased precipitation reduces surface water,” said Jeremy Lichstein, Webb’s adviser and co-author of the study. “But it turns out the physical explanation was already in the scientific literature: rainwater carries heat into the ground and accelerates permafrost thawing, which can open up underground channels that drain the surface.”

If accelerated permafrost thaw is to blame, that’s bad news. Arctic permafrost is a natural storehouse of preserved organic matter and gases that warm the planet.

“Permafrost soils store nearly twice as much carbon as the atmosphere,” Webb said. “A lot of ongoing research suggests that as permafrost thaws, this carbon is likely to be released into the atmosphere as methane and carbon dioxide.”

There is a silver lining to the researcher’s findings. Previous models of lake dynamics predicted lake expansion, which thaws the surrounding permafrost. But because the lakes are drying up, the permafrost near the lakes probably doesn’t thaw as quickly.

“It’s unclear exactly what the trade-offs are, but we do know that expanding the lake results in carbon losses an order of magnitude greater than what is happening in surrounding regions,” Webb said.

To obtain their results, Webb’s team used satellite data identify major trends in surface water changes in the Arctic. Known as remote sensing, satellite imagery helps answer large-scale questions, Webb says.

Arctic lakes are disappearing in a surprise climate discovery

An aerial view of Arctic Lakes showing a significantly drained lake. Credit: David Swanson/National Park Service

“One of the things I really like about using remote sensing is that you can answer what seemed like incredibly important questions – we have the ability to answer them now,” Webb said. “It’s only been in the last five or ten years that we’ve had the computing power and the resources needed to achieve it. “

The research team used a machine learning approach to examine the climate change mechanisms responsible for the change in the surface area of ​​the lake. By mining large sets of satellite images to assess patterns of surface water loss, they were able to analyze decades of data in the Arctic. Their work relied on robust programs, including Google Earth Engine and the Python platform on UF’s HiPerGator supercomputer, to query large data sets and run models.

Webb first set out to explore an entirely different subject: arctic albedo or surface reflectivity. Webb’s early work in Environmental Research Letters have shown that surface water is an important driver of albedo change, but she struggled to find studies that detailed why surface waters were changing in the first place. “I wrote the paper I wanted to cite for my work on albedo,” she said.

To limit the disappearance of lakes, recent research in Frontiers in Environmental Science shows that the best way to save permafrost may be to reduce fossil fuel emissions. Reducing carbon emissions could put the planet back on track by limiting global temperature rise.

“The snowball is already rolling,” Webb said, saying we need to act now to slow these changes. “It won’t work to keep doing what we’re doing.”

Rivers and lakes in Western Siberia emit greenhouse gases into the atmosphere

More information:
Elizabeth E. Webb et al, Permafrost thaw drives surface water decline in lake-rich regions of the Arctic, Natural climate change (2022). DOI: 10.1038/s41558-022-01455-w

E.E. Webb et al, Surface water, vegetation and fire as drivers of terrestrial arctic-boreal albedo feedback, Environmental Research Letters (2021). DOI: 10.1088/1748-9326/ac14ea

Benjamin W. Abbott et al, We Must Stop Fossil Fuel Emissions to Protect Permafrost Ecosystems, Frontiers in Environmental Science (2022). DOI: 10.3389/fenvs.2022.889428

Permafrost Discovery Gateway: … frost/Imagery-Viewer

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