Permafrost and the Ground Beneath You

Most of Alaska is underlain by permafrost, ground that has been continuously frozen for at least two years and, in some parts of the state, for more than ten thousand years. It is not ice visible at the surface. It is frozen ground, soil and rock and organic material locked at temperatures below thirty-two degrees Fahrenheit at depths ranging from a few feet to more than two thousand feet.

Permafrost shapes everything about how Alaska is built, farmed, or not farmed, and how it is changing. Buildings constructed without understanding permafrost sink, tilt, and eventually collapse as heat from their foundations thaws the ground beneath them. The technique of building on pilings, elevating structures above the surface and allowing cold air to circulate underneath, evolved specifically to avoid warming the permafrost below. Look at any older building in Fairbanks that is not on pilings and you can see the result: floors that tilt at five or ten degrees, doors that will not close because their frames have shifted.

Permafrost stores carbon. The organic material frozen in it has been accumulating since the last ice age, pulled from the atmosphere by plants and never allowed to decompose. Scientists estimate that Arctic permafrost holds approximately one point six trillion tons of organic carbon, roughly twice the amount currently in the atmosphere. As global temperatures rise and permafrost thaws, that organic material begins to decompose, releasing carbon dioxide and methane, which accelerate the warming that causes more thaw. This is the feedback loop that climate scientists describe as one of the largest uncertainties in projections of future warming.

Shishmaref, a Iñupiat community of about six hundred people on a barrier island in the Chukchi Sea, has been losing its coastline to erosion accelerated by permafrost thaw and the loss of sea ice that used to protect its shores. The community voted in two thousand sixteen to relocate. Finding the money and a site has taken years.

Permafrost is not a problem Alaska invented. It is the ground Alaska was given. What happens to it now is a problem the rest of the world is still learning to understand.