"Permafrost contains microbes, mammoths, and twice as much carbon as Earth’s atmosphere. What happens when it starts to melt?"
"Flying over Yakutia, in northeastern Russia, I watched the dark shades of the boreal forest blend with patches of soft, lightly colored grass. I was strapped to a hard metal seat inside the cabin of an Antonov-2, a single-engine biplane, known in the Soviet era as a kukuruznik, or corn-crop duster. The plane rumbled upward, climbing above a horizon of larch and pine, and lakes the color of mud. It was impossible to tell through the Antonov’s dusty porthole, but below me the ground was breathing, or, rather, exhaling.
Three million years ago, as continent-size glaciers pulsed down from the poles, temperatures in Siberia plunged to minus eighty degrees Fahrenheit and vast stretches of soil froze underground. As the planet cycled between glacial and interglacial periods, much of that frozen ground thawed, only to freeze again, dozens of times. Around eleven and a half millennia ago, the last ice age gave way to the current interglacial period, and temperatures began to rise. The soil that remained frozen year-round came to be known as permafrost. It now lies beneath nine million square miles of Earth’s surface, a quarter of the landmass of the Northern Hemisphere. Russia has the world’s largest share: two-thirds of the country’s territory sits on permafrost.
In Yakutia, where the permafrost can be nearly a mile deep, annual temperatures have risen by more than two degrees Celsius since the Industrial Revolution, twice the global average. As the air gets hotter, so does the soil. Deforestation and wildfire—both acute problems in Yakutia—remove the protective top layer of vegetation and raise temperatures underground even more."