A New Measure of Earth’s Forests

An International Space Station mission led by the University of Maryland and scheduled to launch next month will comprehensively map the earth’s forests, giving scientists new insights into how much carbon is stored in the planet’s trees and how much carbon dioxide they can absorb.

The Global Ecosystem Dynamics Investigation (GEDI) instrument will be docked with the space station and uses a laser method called lidar to take three-dimensional measurements of the surface.

“It’s going to give us the carbon content of the Earth’s forests at fine spatial resolution for the first time,” Ralph Dubayah, a professor in the Department of Geographical Sciences and the principal investigator of GEDI, said yesterday at a media viewing of the instrument at NASA’s Goddard Space Flight Center in Greenbelt.

The project, a collaboration between UMD and Goddard, was approved in 2014 and is cost-capped at $94 million. Scheduled for a two-year mission, GEDI will be shipped in mid-October from Goddard to the Kennedy Space Center in Florida and launched with a SpaceX resupply mission to the ISS at the end of November.

By measuring tree height and vertical structure, GEDI will provide scientists with data that has applications in everything from understanding snowmelt and the impact of fires and hurricanes to predicting the weather. The interplay between tree cover and rising amounts of carbon dioxide took on more urgency this week as a new United Nations report warned time is running out to blunt severe consequences of the warming climate.

“To be able to have any kind of rational policy about how one protects forests, you have to know what you are starting with,” Dubayah said.

For example, he pointed to the practice of offset programs, where a power company will plant trees to try to counteract its environmental effects. But that only works if the trees last.

“No one tracks how well these trees are doing over time,” Dubayah said. “Are they still growing? At a larger scale, vast swaths of tropical forests are being lost every day. How much carbon is being lost through such deforestation? GEDI will provide that answer.”