This post was originally published on snow.news, my free Substack on snow science and the state of the snowpack.
The cryosphere encompasses all the frozen parts of Earth’s surface: snow cover, glaciers, permafrost, sea ice, ice sheets, ice shelves, icebergs, and river/lake ice.
In the American West and beyond, the cryosphere is a critical source of freshwater, while on the global scale, the cryosphere plays a key role in regulating the planet’s climate by reflecting sunlight (see previous post on albedo). The term derives from the Greek word kryos, meaning “cold” or “frost.”
At snow.news, I’m only covering a piece of the cryosphere—snow cover, with a dash of glaciers and permafrost—but the illustration below shows the cryosphere’s many other components. Sadly, I’ve never laid eyes on sea ice, an ice shelf, or an ice sheet, but maybe I’ll get there one day . . .
Here’s a nice overview from NASA’s Scientific Visualization Studio showing images of the cryosphere from above the poles.
The map below offers another interesting view of the cryosphere, using a Dymaxion projection, which was created by the visionary inventor Buckminster Fuller and looks fit for origami. Antarctica is on the left, and the North Pole is in the middle of the visualization.
Nearly all of the Earth’s snow-covered areas are located in the Northern Hemisphere, and this component of the cryosphere ranges in size from 47 million square kilometers in winter to just 7 million square kilometers in summer, as shown in the graphic below. At its winter maximum, snow covers about one-half of the Northern Hemisphere’s land mass, which speaks to its significance, at least for part of the year.
“The areal extent of snow varies more rapidly and more dramatically than that of any other widely distributed material on Earth,” write Olav Slaymaker and Richard E.J. Kelly in The Cryosphere and Global Environmental Change, the data source for the graphic above.
The chart below, which is based on data from The Global Cryosphere: Past, Present and Future by Roger Barry and Thian Yew Gan, breaks down the components into four categories: snow cover, sea ice, permafrost, and ice. This graphic shows the relative sizes of the cryosphere’s components, with the time of year listed for the seasonal elements (i.e., all of these areas don’t appear on Earth at the same time).
Climate change is already taking a toll on the cryosphere, with warming rates much higher around the poles and even more drastic reductions for snow/ice projected in the decades ahead. For a solid overview of the global impacts, see the Intergovernmental Panel on Climate Change’s “Special Report on the Ocean and Cryosphere in a Changing Climate.” Another good source is the State of the Cryosphere Report published annually by the International Cryosphere Climate Initiative.
