Suppose you could weigh every tree on Earth.
The information would fill in the last big data gap in climate modeling — the carbon volume on land. It would make for more precise predictions, from sea level rise to warming temperatures. It would improve management of crops, forests, water resources, flood planning and other land uses.
So Barry Coyle is doing it — while his group continues to measure the moon.
Coyle, 54, is a Hanahan native and College of Charleston graduate who works as a laser scientist for NASA. He leads the team that just built a laser-reader now circling the planet aboard the International Space Station. Its job is to assemble a database of the carbon load in trees worldwide.
"Literally, we're going to weigh the trees on the planet," Coyle said.
Trees absorb carbon for food and release the air that living things breathe. A living tree is about 10 percent carbon, so if you know how much carbon is in a tree, you know how much the tree weighs.
Carbon dioxide emissions are considered the leading man-made cause of the warming air and sea. So if you monitor changes in the forests' carbon load, you can answer two other key questions, according to NASA:
- What role will the land play in absorbing carbon dioxide emissions contributing to climate warming?
- How will that warming ecosystem affect habitat?
Answering these questions is critical for understanding the future path of global climate change and the Earth’s biodiversity, NASA said in its explanation of the GEDI, or Global Ecosystem Dynamics Investigation project.
The Star Wars pun is deliberate: Jedi, of course, use laser swords.
"GEDI is quite certainly an impressive instrument. It will give us quite a bit more information about the vertical structure of plants and will improve ecosystems science," said April Hiscox, a University of South Carolina geography professor.
GEDI readings could provide real-time information for dealing with disasters.
"For large disasters, such as the volcanic eruption of St. Helens or Hurricane Michael, the instrument could provide broad area information such as mass movements or vegetation damage that would otherwise be challenging to collect in a short time period," said University of South Carolina geography professor Michael Hodgson.
The equipment aboard the space station is laser and lidar — a reader that works on the principle of radar, but uses light from a laser. The science is "very complicated," Coyle acknowledges. So maybe it's better to tell the story how he came up with it.
He was flying to Greenland. The NASA engineering team was on its way to use newly built lasers to measure glacier ice sheets when they decided to calibrate the equipment while over the forests in the Northeast.
"We got crazy returns," Coyle said.
They realized the laser pulses were bouncing differently off different densities of carbon in the forests and open fields. They also realized that watching it, "you can literally see the planet breathe," he said.
The team made that observation in 1994. Four years later, the space station launched and researchers formed a long line for grants and space to do studies aboard. Coyle spent the next two decades trying to get the carbon-volume project funded.
While he was at it, his engineering group built, among other projects, the Lunar Reconnaissance Orbiter, which is now circling the moon and streaming measurements so fine they are mapping the surface down to the centimeter.
Coincidentally, the Orbiter measurements were used to pinpoint the exact moment of totality during the solar eclipse in 2017. Coyle was in the quad at the College of Charleston when students there let out a whoop at that moment. It gave him goosebumps, he said.
GEDI is now reading a little more of the globe with each pass of the space station. It's expected to take two years to get a complete set of measurements one square kilometer each, with a lot of overlap. The first of the data, though, will soon start downloading.
It is "the last great data mass to gather," Coyle said.