What lies beneath: As earth warms, diseases within permafrost become a bigger worry
SARA GOUDARZI, SCIENTIFIC AMERICAN, at Salon
http://www.salon.com/2016/11/05/what-lies-beneath-as-earth-warms-diseases-within-permafrost-become-a-bigger-worry_partner/
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This past summer anthrax killed a 12-year-old boy in a remote part of Siberia. At least 20 other people, also from the Yamal Peninsula, were diagnosed with the potentially deadly disease after approximately 100 suspected cases were hospitalized. Additionally, more than 2,300 reindeer in the area died from the infection. The likely cause? Thawing permafrost. According to Russian officials, thawed permafrost — a permanently frozen layer of soil — released previously immobile spores of Bacillus anthracis into nearby water and soil and then into the food supply. The outbreak was the region’s first in 75 years.
Researchers have predicted for years that one of the effects of global warming could be that whatever is frozen in permafrost — such as ancient bacteria — might be released as temperatures climb. This could include infectious agents humans might not be prepared for, or have immunity to, the scientists said. Now they are witnessing the theoretical turning into reality: infectious microorganisms emerging from a deep freeze.
Although anthrax occurs naturally in all soil and outbreaks unrelated to permafrost can occur, extensive permafrost thaw could increase the number of people exposed to anthrax bacteria. In a 2011 paper published in Global Health Action, co-authors Boris A. Revich and Marina A. Podolnaya wrote of their predictions: “As a consequence of permafrost melting, the vectors of deadly infections of the 18th and 19th centuries may come back, especially near the cemeteries where the victims of these infections were buried.”
And permafrost is indeed thawing — at higher latitudes and to greater depths than ever before. In various parts of Siberia the active layer above permafrost can thaw to a depth of 50 centimeters every summer. This summer, however, there was a heat wave in the region, and temperatures hovered around 35 degrees Celsius — 25 degrees warmer than usual. The difference possibly expanded or deepened the thaw and mobilized microorganisms usually stuck in rigid earth. Although scientists have yet to calculate the final depth, they postulate that it is a number that has not been seen in almost a century. Permafrost thaw overall could become widespread with temperatures only slightly higher than those at present, according to a 2013 study in Science. Heat waves in higher latitudes are becoming more frequent as well.
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