Alaska is experiencing the rainiest five years in its century-long meteorological record. A new study by scientists is looking at how the increased rainfall is adding to the existing problems of permafrost thaw.

Permafrost underlies 85% of the state of Alaska and about a quarter of the Earth’s Northern Hemisphere. This is a global issue.

Thomas A. Douglas, lead author , U.S. Army Cold Regions Research and Engineering Laboratory, said:

“In our research area the winter has lost almost three weeks to summer. This, along with more rainstorms, means far more wet precipitation is falling every summer.”

For those living in Arctic regions this change in the climate will affect their daily lives. Permafrost locks about twice the carbon that is currently in the atmosphere into long-term storage and supports Northern infrastructure like roads and buildings.

The study which took place near Fairbanks, Alaska, was conducted over 5 years. More rainfall led to deeper thaw across all sites. After the wettest summer in 2014, permafrost didn’t freeze back to previous levels even after subsequent summers were drier.

Vegetation cover also affected the rate of permafrost thaw.  Forests, especially spruce forests with thick sphagnum moss layers, were the most resistant to permafrost thaw.

As Alaska becomes warmer and wetter, vegetation cover is projected to change and wildfires will disturb larger swathes of the landscape.

Thomas A. Douglas continued:

“I was just at one of our field sites and you need hip waders to get to areas that used to be dry or only ankle deep with water. It is extremely wet out there. So far this year we have almost double the precipitation of a typical year.”

Postdoctoral fellow Catherine Dielemen associated with Merritt Turetsky’s research group uses a frost probe to determine the location of surface permafrost beneath the ground surface in interior Alaska. CREDIT Merritt Turetsky

Merritt Turetsky, Director of the University of Colorado Boulder’s Institute of Arctic and Alpine Research (INSTAAR) and a coauthor of the study, said:

“This study adds to the growing body of knowledge about how extreme weather–ranging from heat spells to intense summer rains–can disrupt foundational aspects of Arctic ecosystems.

“These changes are not occurring gradually over decades or lifetimes; we are watching them occur over mere months to years.”

Reporter: Fiona Grahame