Stampede Trail has a story of permafrost's warming potential
Each fall, beginning in the early 1970s—decades before the actions of Christopher McCandless made a gravel road in central Alaska the setting of a bestselling book and movie—Tom Osterkamp was driving the Stampede Trail near Healy to reach his favorite moose-hunting areas.
In 1985, Osterkamp, a professor emeritus and permafrost researcher with the University of Alaska Fairbanks’ Geophysical Institute, remembered a lake with a view of Denali when he was searching for sites to study permafrost. He returned there, a few miles up the Stampede Trail, drilled a deep borehole in the tussock tundra near the lake, and set up a system to measure the temperature of the ground at different depths.
Every study site is a calculated gamble, where researchers guess from where, over time, the best information will emerge. The spot Osterkamp chose near Eightmile Lake has turned into one that is giving scientists insight on how thawing permafrost could cause the world to become warmer.
“(It was) the first one out of more than 20 of my permafrost observatories that showed any effects that could be associated with the changing climate,” Osterkamp said from his home in Saint Clair, Missouri, where he has lived since retiring from the university in 1997.
By checking temperature data every year, Osterkamp noticed by 1989 that the permafrost began to warm around Eightmile Lake. He saw that the ground there was getting bumpy, and small pits were beginning to form. After watching the site for several more years, he figured the permafrost was thawing because thick blankets of snow during the 1990s were insulating the ground from the frigid air of winter.
“Once I realized that the permafrost was thawing naturally, I knew it was a very important site,” he said.
He shared the news of this dynamic area with UAF’s Terry Chapin, who in turn contacted Ted Schuur of the University of Florida. Schuur who wrote a proposal and got money for a post-doctoral scientist, Jason Vogel, to take a close look at what was happening off Stampede Trail.
From 2004 to 2006, Vogel measured the greenhouse gas carbon dioxide as it circulated between the atmosphere and tundra near Eightmile Lake. The readings were telling him things so compelling that he, Schuur, Osterkamp, and a few other scientists submitted their results to the journal Nature, which just published them.
In the paper, the authors ponder whether faster plant growth that results from a warmer northern landscape will take up the carbon dioxide released by microbes as permafrost thaws.
Permafrost, ground that has remained frozen through the heat of at least two summers, consists of a good deal of ancient plant matter that stopped decomposing when the ground froze (in the case of the Stampede Trail site, several thousand years ago). As permafrost thaws, that organic matter becomes available for tiny microorganisms to eat, who then emit carbon dioxide after finishing their meals.
At Eightmile Lake, the early thawing that Osterkamp noticed has stimulated tundra plants to take up more carbon dioxide than the microbes have been giving off. But that may not be the case in the near future, according to the scientists’ calculations.
“The microbes overwhelm plants after a while,” Vogel said over the phone from Gainesville, Florida. “It’ll take a very small amount of additional thawing (for that to happen at the Stampede Trail site). Plants have an upper limit to their potential photosynthesis; microbes are more limited by the amount of available carbon. So, once carbon in the soil becomes available (unfrozen), they become more and more active.”
With the microbes going crazy, areas of former permafrost like the tundra near Eightmile Lake could become a new source of carbon dioxide in the air. Should the big thaw continue, the tundra of Alaska, Canada, and Siberia could release as much locked-up carbon as does the current deforestation of the tropics, the researchers said.
