Alaska is Melting

ENVIRONMENT

A new study suggests that Alaska’s permafrost is unleashing an increasing amount of carbon dioxide as it thaws. (Washington Post)

What is permafrost? Use our super-short reference to find out.

Teachers, scroll down for a quick list of key resources in our Teachers Toolkit.

There are four types of permafrost: continuous, discontinuous, sporadic, and isolated. Each type has an “active layer” of soil, which freezes and thaws every year. The thickness of the active layer contributes to the amount of carbon released and the vegetation that the permafrost can support.
Illustration by Chuck Carter, National Geographic

Permafrost stretches across the Arctic region, although its extent is shrinking and predicted to dwindle to the High Arctic within the century.
Map by National Geographic Maps

Discussion Ideas

  • A new study suggests thawing permafrost is contributing to climate change. What is permafrost? Take a look at our super-short reference for some help.
    • Permafrost is a permanently frozen layer of ground. It consists of soil, gravel, and sand, usually bound together by ice. Permafrost can be terrestrial (on land) or marine (beneath the Arctic Ocean, called subsea permafrost).
      • Permafrost extends throughout the Arctic region, with the largest deposits in Russia, Canada, the U.S. state of Alaska, and Greenland.

 

  • How does permafrost help maintain Earth’s climate?
    • Permafrost is a major carbon sink, meaning it absorbs more carbon dioxide than it emits. Forests and the ocean are Earth’s other big carbon sinks.
      • The carbon sequestered by permafrost comes from decaying plant and animal material in the soil. Frozen soil traps carbon, preventing its release to the atmosphere. In this way, some carbon has been trapped for hundreds of thousands of years by permafrost. (This scientifically valuable material is called relic permafrost.)

 

  • How does thawing permafrost contribute to climate change?

 

  • So, a warmer climate is contributing to thawing permafrost … which is contributing to climate change. What other impacts might thawing permafrost have on the Arctic landscape?
    • soil erosion. As permafrost thaws, soil becomes weaker and more prone to erosion. This would have many consequences, such as:
      • The foundations for buildings (houses, schools, hospitals, businesses) would become much less stable. This would have demographic and economic consequences.
      • Landslides and other incidents of mass wasting would likely be much more common.
    • coastal erosion. Without the barrier of frozen ground, waves are much more likely to cause coastal erosion, threatening coastal residences and businesses.
    • thermokarst. Thermokarst describes the “process by which landforms result from the thawing of ice-rich permafrost or the melting of massive ice.” For instance, when permafrost layers in the soil thaw, the ground sags and sometimes creates shallow ponds. This can cause nearby trees, which have very shallow roots, to lean toward the depression. These “drunken forests” can destabilize the ground, making it difficult to develop and more prone to mass wasting.
    • drained wetlands. Previously frozen water is more likely to drain, seep further down, or evaporate, reducing the number of Arctic lakes and wetlands. This image is a striking illustration of “vanishing permafrost.”
    • sea level rise. The seemingly tiny amount of water released by permafrost could be enough to help raise global sea levels by 3 to 10 centimeters (1 to 4 inches).

 

  • Why do some scientists see a hopeful sign in the latest permafrost study?
    • Warmer temperatures are causing “Arctic Greening,” the process of vegetation spreading throughout high altitudes. (Learn more about the Greening Arctic here.) Some scientists hope this increased forest cover will act as a new carbon sink in the Arctic.

 

TEACHERS TOOLKIT

Washington Post: ‘We all knew this was coming’: Alaska’s thawing soils are now pouring carbon dioxide into the air

Nat Geo: What is permafrost?

National Snow & Ice Data Center: Climate and Frozen Ground

(extra credit!) (paywalled) Proceedings of the National Academy of Sciences: Carbon dioxide sources from Alaska driven by increasing early winter respiration from Arctic tundra

2 responses to “Alaska is Melting

  1. Pingback: Landslides Help Explain How Life Reaches Remote Islands | Nat Geo Education Blog·

  2. I think that it is worth discussing this problem as often as possible. And so many unnecessary questions will be discarded. Thanks for useful ideas, I think it will be useful in my practice! 🙂

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