Story

Melting Permafrost Raises Fears of Decades-old Pathogens

29968588975_a685f140f3_k.jpg

Permafrost disturbances in the 2014 study area on Forsheim Peninsula, Ellesmere Island, Nunavut, Canada. Image by A. Cassidy. Canada, 2014.

Permafrost disturbances in the 2014 study area on Forsheim Peninsula, Ellesmere Island, Nunavut, Canada. Image by A. Cassidy. Canada, 2014. 

In 2011, Russian researchers published a study calling attention to an unusual hazard posed by our changing climate: Pathogens awaking inside the melting permafrost.

Writing in the journal “Global Health Action,” Boris A. Revich and Marina A. Podolnaya described 200 burial grounds containing cattle killed long ago by anthrax. All of the burial grounds lie in the vast territory of Yakutia, some 1.2 million square miles of frozen land, about 40% of it above the Arctic Circle.

Anthrax is an especially hardy pathogen, able to survive for 105 years in the layer of frozen soil and rocks known as permafrost. In previous decades, anthrax outbreaks in Yakutia have killed cattle, deer and people.

Melting of the Arctic permafrost has now made it possible for the sea to devour more than 65 feet of coastal land per year in some places. 

“As a consequence of permafrost melting,” the Russian researchers warned, the causes of deadly infections “may come back.”

That appears to be what happened last summer, five years after their warning.

In the Siberian town of Salekhard near the Ural Mountains, a 12-year-old boy died of anthrax and at least 20 other people were sickened. The outbreak was linked to the thawing of a 75-year-old reindeer carcass during a summer heat wave. The reindeer was believed to have been infected with anthrax before its body froze.

When he learned of the outbreak last summer, “I thought that I was right when I spoke about the epidemic danger of melting permafrost,” says Revich, head of the Laboratory of Environmental Health, Institute of Forecasting for the Russian Academy of Science.  

“The degree of the outbreak was quite surprising,” says Jeniel E. Nett, an assistant professor at the University of Wisconsin School of Medicine and Public Health. “This is the first example I can remember in terms of the permafrost releasing a pathogen to this degree.”  

Long before last summer’s outbreak, however, the thawing of cattle burial grounds in 1969 and 1977 apparently released anthrax, killing Siberian reindeer in Taymyr, a region of the Russian Arctic, according to Revitch and Podolnaya.

For more than 30 years, Marcia Bjornerud, a professor of geology at Lawrence University in Appleton, has been witnessing the changes in the permafrost while conducting her own study of how tectonic processes create mountains in the high arctic regions of Canada and Norway.

“Climate change is not my focus, but while I’m doing my work, I’ve seen the glaciers shrinking and the permafrost melting,” says Bjornerud. 

“We have about 10,000 years of organic matter frozen in permafrost. When that starts to decompose, it’s kind of a time bomb.” 

The permafrost’s organic matter includes moss, grass and bird droppings.

What other pathogens besides anthrax may be capable of rising from the melting permafrost is not clear. Some have speculated about the possible reemergence of smallpox trapped in bodies buried in the permafrost, though Nett said there have been no reported cases of the disease reawakening in this manner.

Even if we’re spared attacks from other microbial foes in the permafrost, anthrax is likely to reemerge from time to time.

“It’s almost indestructible,” says George C. Stewart, professor of microbial pathogenesis and chairman of the department of pathobiology at the University of Missouri.