There are, at the moment, nearly 200,000 glaciers on Earth. They have a volume of nearly 106,000 miles cubed, and cover an area of about 453,000 miles squared. This means they cover an area roughly equivalent to that of Germany, Poland, and Switzerland combined.
We know this in large part because of satellite data. But we know it more specifically because of a new survey, just published by an international collection of scientists in the Journal of Glaciology, that uses sent-from-space data to provide a comprehensive view of the world's glaciers. The new inventory is based on information compiled by the Randolph Glacier Inventory in New Hampshire. It's the first statistical analysis of the world's glacier distribution.
So why do a survey like this? And why do one now?
We need to understand the dynamics of glaciers—which are frustratingly inclined to melt when temperatures warm—to understand, among other things, the water dynamics of the planet at large. The survey was rushed to completion to be of use in the recently published Fifth Assessment of the Intergovernmental Panel on Climate Change, where it offered insight on how the world's existing glaciers might interact with each other—and, by extension, with us.