What are Alaska’s soils telling us?

Soils in Alaska are quite different from those in the lower 49 states. Discoveries there in the last few decades have even changed the way soil scientists are trained. And Alaskan soils are telling us a story about climate change.

A soil core showing the ice wedges in the top layer of soil. Taken in upper Alaska.

Soil scientists use soil cores to look at soil structure at various sites. In this core, the top layer has clear ice wedges. Cr: David Weindorf

Prior to 2000, soil scientists considered soil temperatures below 5°C “biological zero.” They didn’t expect activity from soil microbes.1 However, researchers discovered significant microbial activity below 5°C, not just in Alaska, but Antarctica, too.2 Also, a large variety of plant life thrives on soils in Alaska. This includes areas where soil temperatures rarely exceed 5°C during the summer.

Our understanding of water movement in annually frozen soils is also very complicated in northern soils. Snow accumulates during winter in both Arctic and Subarctic regions. Snow is important to soil – it insulates the ground throughout the winter. It also provides essential moisture during spring.

The interaction between the melting snowpack and underlying annually frozen soil is complex. In the lower states – the ones that get snow – snowmelt moves down through soil.  It can also move over soil, depending on the rate of melting. In Alaska, as snowpacks and the underlying soils warm up, cold water enters the frozen soil. Water and ice coexist in a precarious balance for several weeks. Believe it or not, some of this water – though it’s not exactly the liquid phase of H2O – can move through the frozen soil. That means water from melting snow is absorbed by frozen soil. It doesn’t run off, as it might in the lower states. It’s a complicated process, and soil scientists continue to study it. As the climate warms these water movement processes may change.

Alaska Soils Mark Clark 3 cropped x 300

From Interior Alaska, this photo shows fireweed in bloom one year following fire. Although the soil is permafrost (a gelisol in soil science terms), moss commonly grows in this area. Fire kills the surface moss mat which usually insulates the soil. Within a few years after the fire, the soils warm, and the permafrost layer melts, allowing for a wild flower bloom. Cr: Mark Clark

Alaskan soils are telling us the climate is changing. This is especially true in the extensive permafrost landscapes of Interior and Western Alaska. The climate in Alaska varies regionally with temperatures moderated by the marine environment that surrounds the land. But winter temperatures are now significantly warmer. The amount of pack ice is in decline, and ice forms later in fall and melts earlier in spring.

In addition, coastal areas along the Bering and Chukchi Seas are no longer protected by ice from fall storms. Coastal areas are eroding at an unprecedented rate. As one would expect, terrestrial systems are also changing as temperatures are affected by the warmer oceans.

The receding permafrost affects residents in Alaska. The Inupiaq people have called the island of Shishmaref for thousands of years. As sea ice retreats and coastal storms increase, the community is faced with a disappearing island. Relocating the community of Shishmaref will cost $200 million. They are losing their jobs, their homes, and their community.

Alaskan roads, buildings, and bridges can be affected by the warming climate. Buildings that are close to the formerly frozen bodies are also at risk – and even buildings in the interior area are affected. Arctic engineers estimate maintenance costs in excess of $5 billion in the next several decades to offset soil collapse.

Finally, as the climate continues to warm, we may need to use Alaska for agricultural land. This is especially true as the average air temperature rises. Alaska is largely undeveloped with millions of acres of land suitable for agriculture. Alaska has the potential to offset some of the climate change threats that face America’s food security.

Answered by Mark H. Clark, CPSS, former NRCS Alaska Soil Scientist

To learn more about Alaskan soils and climate change, visit Between Earth and Sky.

  1. https://soilsmatter.wordpress.com/2015/07/14/is-it-true-bacteria-live-in-the-soil-isnt-that-bad/
  2. https://soilsmatter.wordpress.com/2016/02/01/ive-heard-that-soil-microbes-are-living-in-antarctica-how-can-that-be/
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