Using satellite images the survey team counted all the lakes in the world that were bigger than half an acre, says Uppsala University in a release. It's the first time we've ever had such a thorough census of the world's lakes, they say.
Though there are some huge, well-known lakes in the world—North America's Great Lakes, for instance, or Africa's Lake Victoria—most of the world's lakes are just little things that dot the landscape at northern latitudes, or fill the trenches dug as glaciers retreated thousands of years ago. Roughly 70 percent of the Earth's surface is covered by water, but less than four percent is covered by lakes. These little lakes don't take up much room, but make up the bulk of the numbers.
Similarly, it's many of these lakes that are at risk of disappearing as the climate changes.
In northern Canada, for instance, researchers recently found that the thousands of small lakes that dot the permafrost terrain have been drying up at a rate faster than at any point in the past 200 years. Hampered by a lack of snowfall, many of these lakes could be dried and gone within a few decades, if not a few years.