Joseph Cook took to the ice to learn about the polar ice caps of Mars, but he found something almost as otherworldly on Earth. For his graduate research in glaciology, Cook’s plan was to study depressions on glaciers as a way to learn more about mysterious Swiss-cheese pits in Martian ice. But, he says, once he began exploring the holes in 2009, “I was hooked.”
It’s easy to understand Cook’s fascination. Each hole is its own tiny world, an ecosystem unto itself that supports a host of life-forms, including tardigrades — or water bears — and other small organisms. These water-filled divots develop when dark grains of bacteria-specked dust collect on a glacier or ice sheet and absorb heat from the sun. The granules, called cryoconite, begin to melt the ice, forming cylindrical wells 1 to 50 centimeters wide. The grains settle into a layer of cryoconite sediment on the bottom.
Cryoconite holes appear on glaciers all over the world, from Antarctica to Greenland to the Himalayas. But climate change threatens many of these slabs of ice, and as they melt, the distinctive divots they harbor are vanishing, too — just as scientists are beginning to understand them. And the cryoconite organisms themselves may be speeding up the process. “They may well be catalysts of their own demise,” says Cook, of the University of Sheffield.
Cook and other scientists aim to figure out how these miniature ecosystems work — and their role in glacial melting — before the ice disappears.
