We know the drought we experienced this year affected our gardens and farmlands, but did you know it could be detected from space?
These maps are based on data from NASA’s Gravity Recovery and Climate Experiment (GRACE) satellites. The paired satellites detect small changes in the Earth’s gravity field caused by the redistribution of water on and beneath the land surface.
According to the National Drought Mitigation Center, the paired satellites travel about 137 miles (220km) apart and record small changes in the distance separating them as they encounter variations in the Earth’s gravitational field.
As NASA points out, these maps are not an attempt to represent consumption of water on Earth, but rather, the changes that occur to water storage due to seasonal patterns, weather, and climate.
When the satellites encounter a change in the distribution of Earth’s mass—such as a blanket of fresh snow on California’s Sierra Nevada—they are pulled toward the mountains a tiny bit more than normal. By tracking trends in how the satellite orbits change, researchers can calculate how gravity is changing on Earth. So when groundwater supplies dwindled in the United States in 2011 and 2012, that region of the planet had a little less mass and gravitational pull. The satellite orbits moved a bit in response, allowing GRACE to reveal the change in groundwater storage.
While we couldn’t physically feel the affects of less mass and gravitational pull we will certainly feel our pocket books become a little lighter as food prices rise.