Climate change leading to increased erosion in Alaska due to inability of permafrost to reform.

In a self-perpetuating cycle, global warming leads to permafrost thaw, which leads to erosion, which contributes to climate change. In a warming climate, Alaskan permafrost is unable to reform fast enough to replace what has thawed in warmer months.

Koyukuk River, Alaska
The Koyukuk River flood plain was studied to analyse the impact of climate change on permafrost thaw and reformation

The Arctic is experiencing warming at a rate estimated to be 4 times faster than the global average in a phenomena known as 'Arctic amplification'. This is largely due to the loss of sea ice and permafrost, resulting in a reduced albedo effect, exacerbating warming. This consequential warming makes it harder for sea ice and permafrost to form, not only increasing the risk and impact of warming, but also leaving areas of land vulnerable to erosion.

A recent study published in American Geophysical Union journal AGU Advances highlights the impact of warming on permafrost formation in Alaska, and subsequent erosion, further contributing to climate change.

The importance of permafrost

Permafrost is the term used to describe any ground, soil, sand, sediment or rock, that has remained frozen at or below 0oc for at least 2 years. As a result, it is generally found in polar regions, mostly in the Arctic with some found in the Antarctic and high mountains.

A recent study analysed the impact of climate change on permafrost formation in the Koyukuk River floodplain, Alaska. Part of this floodplain lies in what is known as the ‘Gates of the Arctic’.

A key concern of the research was the impact of climate change on permafrost thaw and formation, and subsequent erosion. Nathan Brown, Professor of earth and environmental sciences at University of Texas, Arlington says “Under a warming climate, a major question is whether arctic rivers will erode permafrost in thawing riverbanks faster than permafrost can regenerate.”

Impact on climate change

Permafrost influences approximately 25% of land in the Northern Hemisphere, so it is vital to understand its dynamics, and response to climate change. Brown says "In the Northern Hemisphere, much of the ground is permafrost, meaning it is frozen year-round. Permafrost is a delicate natural resource. If it is lost faster than it is regenerated, we endanger infrastructure and release carbon, which can warm the atmosphere,”

Alaska Permafrost
Permafrost is thawing faster than it is able to reform, leaving areas vulnerable to erosion, and contributing to climate change

In their study, permafrost deposits were dated to analyse the speed at which permafrost forms, and how this has changed over time. Brown continues “By dating these permafrost deposits, we found that permafrost formation in this region can take thousands of years.”

With formation taking thousands of years, understanding the interplay between climate change and permafrost formation, as well as resulting impacts on climate change is crucial. Brown says “Under a warming climate, permafrost formation is expected to take longer, while thawing permafrost riverbanks will become more susceptible to erosion. The net result will be loss of permafrost and contribution of carbon to the atmosphere.”

Source of the news

Madison M. Douglas et al (2024) Permafrost Formation in a Meandering River Floodplain American Geophysical Union journal AGU Advances