Mapping Arctic Warming

Like a giant ice cream cake left outside on a hot summer day, the Arctic is melting. In the land of frozen Earth, new wetlands are appearing, as are lake-sized puddles and kilometers-long rivulets of meltwater. Scientists have long known about thermokarst—areas where permafrost has thawed and given way to land surface collapse and eroded gullies. But until now, they did not know just how much of the Arctic landscape was susceptible to thermokarst.

According to new research, it makes up roughly 20 percent of the northern permafrost region. Thermokarst landscapes store as much as half of the region’s soil organic carbon (SOC)—a potentially significant source of future greenhouse gasses.

The maps above, which show the northernmost latitudes of North America and Eurasia, were created using data from the study. The map below offers a closer look at Siberia. The different colors reflect the types of landscapes—wetlands, lakes, hillslopes, etc.—where thermokarst is likely to be found today and where it is most likely to form in the future. The darker the color, the higher percentage of the landscape is covered by that landform. Coverage is classified as very high when 60 to 100 percent of the land fits into that category. High means 30 to 60 percent coverage; Moderate is 10 to 30 percent, and low is below 10 percent. Hillslope thermokarst landscapes do not reach very high levels, the researchers found.

In places where the permafrost has melted and become thermokarst, wetlands were the most prevalent landform, accounting for nearly 8 percent of the northern landscape. Lake thermokarst covered 7 percent and hillslope thermokarst was prevalent in 5 percent of the area. However, thermokarst landscapes sometimes overlapped, accounting for the marbled appearance of the maps.


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