Scientists can see and fact-check from space how ice melts in Greenland each year.
The fringe of the Greenland ice sheet endures an annual freeze-and-thaw cycle. Plunging temperatures and ample snow in fall and winter replenish the massive ice sheet, which covers 80 percent of the country's landmass. Endless sun in spring and summer melt ice at the surface and the meltwater runs off through the country's rocky edges to the oceans. This kind of natural cycle allows scientists to observe the impact of climate change over time. Satellites have provided continual monitoring of Greenland's ice cover since 1979. While annual melt patterns vary greatly, three decades of data reveal trends of increasing surface melt and number of melt days, as seen in the first visualization below. The annual Greenland melt also opens a window on one of the most important aspects of science by satellite: With more than one satellite instrument measuring the melt, scientists can compare data to provide a measure of confidence in their observations. In the second visualization, watch how two different satellite datasets created almost mirror-image views of Greenland's ice melt extent in one year.