Some glaciers are shrinking by nearly 100 feet a year—and it's now possible to watch that happen with satellite data. Researchers at the German Aerospace Center, DLR, recently finished creating the most precise 3D map of Earth ever made.
The satellite system can show detailed changes on the planet within a meter of accuracy. It's more precise than previous topographical maps by a factor of 30. While satellites have been good at navigation for a while—if you pull up a map app on your phone for directions, it can find your location within a few feet—topography has been a harder challenge. Until recently, satellite systems trying to map a hill or the height of trees in a forest might have been off by more than 10 meters.
The system uses two powerful satellites working in tandem and can map the entire Earth—around 150 million square kilometers—in a year. But the researchers are also using it to map changes more often in critical areas, such as Greenland, so other scientists can better understand systems that were nearly impossible to measure in the past.
On a glacier, it's now possible to understand both height and volume. "You can calculate the volume of ice that is melting and calculate the contribution to sea level rise from this particular glacier," says Alberto Moreira, director of the institute at DLR that designed the system.
In a tropical rainforest, the maps can be used to measure how quickly trees are growing or dying. "The biggest unknown in the carbon cycle is how much carbon is absorbed by forests from the atmosphere," he says. "We know how much carbon dioxide is going into the atmosphere every year, and how much the oceans are uptaking. But the forests are not well understood."
The researchers have also used the maps to track a volcano eruption in Mexico and the growth of crops in a rice paddy; because each field grows at a slightly different rate, the data can help farmers know the perfect time to harvest each location.
The satellites map the Earth using radar, which is the only mapping technology that can work in any weather conditions or time of day.
In the specific areas they have focused on so far, the researchers update maps every 11 days. But they are working on a new system that will be able to map the entire planet twice a week.
There are technical challenges; for example, the current satellite, pumping six kilowatts of power, can only run for five minutes before it overheats and has to shut down for an hour. The new system will use four times less power, so it can run continuously. The researchers are also developing technology that can store and process the enormous amount of data gathered by the satellites.
"Users don't want the radar data," says Moreira. "They just want to see the changes in a glacier, or biomass changes in a forest, and so on. So we need huge cloud computing and a thriving system in order to provide this."
Along with the free data for researchers, the team works with Airbus to sell data to companies that use it for applications like precision agriculture. They also want to make a low-res version available to anyone—you can't see it now because the data would crash your computer.