By David Kattenburg

Planet Earth is covered in water. Ninety-seven percent is in earth’s oceans. Most of the rest is frozen solid — locked up in sea ice and terrestrial ice sheets, glaciers and permafrost.

Earth’s cryosphere plays a huge role in regulating climate. Polar ice and snow reflect solar rays, down-regulating Earth’s natural greenhouse.

At the same time, sea ice insulates waters below, keeping them relatively warm. Polar waters store massive amounts of heat.

At transition zones between ice (freshwater) and open water (cold, salty and dense), ‘thermohaline’ currents flow, pushing colossal volumes of water (measured in Sverdrups; a million cubic meters of water per second) down to the bottom and along the floors of the Arctic, north Atlantic, Pacific and Antarctic circumpolar oceans, from whence they creep all around the planet.

Wherever cold, nutrient-rich waters rise back to the surface — they do in various spots — photosynthetic creatures go crazy, and the rest of the marine biosphere chows down. (amidst lots and lots of plastic).

Like that proverbial canary in a coal mine, Earth’s cryosphere is in trouble. As the atmosphere warms, ‘positively forced’ by an unrelenting flow of human-generated greenhouse gases, the cryosphere is slowly melting. Various positive feedbacks, in turn, threaten to push Earth into ‘hothouse mode’.

Thomas Wagner is watching. Wagner is Program Scientist for the cryosphere at the National Aeronautics and Space Administration. NASA. Listen to our conversation here:


Cambridge Bay, Nunavut