The Zombie Diseases of Climate Change
From the air, the coast of Greenland appears vast and tranquil. Hundreds of fjords, their surfaces a mirror of blue sky and cloud bottoms, divide the territory. In the gaps between them, the terrain folds over itself, hill over hill, descending into obsidian lakes. The turf is covered in the waxy pastels of alpine dwarf willows and the dull white of age-bleached lichen.
Let me orient you. At the top of the world, there is water. Television anchors sometimes speak of the Arctic Ocean as the “polar ice cap,” but that is a contingency of temperature and a quirk of today’s climate. Consider it instead a landlocked ocean, a northern Mediterranean Sea. Surrounding it sit great landmasses—Europe, Asia, North America—and a surfeit of islands. Among the largest are Svalbard, which is due north of Norway and so dense with polar bears that everyone who strays beyond its sole settlement must carry a rifle; Novaya Zemlya, the site of the largest atomic test ever conducted; and Greenland.
In all of these places, rich, marshy soils run from the edge of the interior ice right up to the ocean cliffs. Once, this dirt gave rise to lush ferns and open grasslands; now, after 35,000 years of frigid cold, we call them permafrost.
Despite their name, they are not permanently, or entirely, frozen. Every winter, a sheet of ice blossoms over the Arctic sea, and the soils seize shut with frost. Then, during the long summer days, the ice breaks up and the permafrost partially thaws.
Lately, as summers have lengthened and winters have warmed, this seasonal transformation has lost its symmetry. What biologists call the permafrost’s “active layer”—the part of the dirt where microbes and other forms of life can live—now reaches farther underground, and further north, than it has for tens of thousands of years.
The newly active permafrost is packed with old stuff: dead plants, dead animals, mosses buried and reburied by dust and snow. This matter, long protected from decomposition by the cold, is finally rotting, and releasing gases into the atmosphere that could quicken the rate of global warming.
This matter is also full of pathogens: bacteria and viruses long immobilized by the frost. Many of these pathogens may be able to survive a gentle thaw—and if they do, researchers warn, they could reinfect humanity.
Climate change, in other words, could awaken Earth’s forgotten pathogens. It is one of the most bizarre symptoms of global warming. And it has already begun to happen.