 Radio Script 1999 __________________
Peering Through the Leaves Don't have RealAudio player? Download free software.
INTRO: Next year, Alaska's new Kodiak Rocket Launch Complex will send its first satellite into orbit. As Doug Schneider reports on today's Arctic Science Journeys, the 60-million-dollar NASA satellite will use lasers to map the world's forests--quite literally from treetop to forest floor. STORY: From its orbit 400 kilometers above the earth, scientists say NASA's Vegetation Canopy Lidar satellite will give them their best view yet of global deforestation and its effect on the climate. The satellite is the first to be launched from Alaska's new complex on Kodiak Island. Soon after it reaches orbit, five beams of laser light--called lidar--will pulse to the earth some 240 times a second. Light reflected back to the satellite will give scientists a three-dimensional view of the world's trees--everything from Alaska's boreal forests to the tropical jungles of South America. Dr. Ralph Dubayah, from the University of Maryland, is the project's chief scientist. DUBAYAH: "It measures how tall the trees are and it measures the vertical distribution of trees and branches. It actually penetrates through the canopy, all the way to the ground. And because you get a signal off the ground and off the top of the canopy you can see how tall the trees are by looking at that difference. And you also get a vertical record of everything in between. So where you have more leaves and branches you'll have more reflectance and a stronger return at the satellite. And where you have less leaves and branches you'll have a weaker return. And we do that vertically through the canopy, at any particular height. What we then get is a vertical distribution of the canopy "stuff" if you will--the leaves and branches." Scientists say forests are key to understanding climate change because they remove the greenhouse gas carbon dioxide from the atmosphere and turn it into living plant tissue--things like leaves, branches and roots. Scientists are interested in knowing just how much carbon dioxide the world's forests are stockpiling. Dr. Robert Knox is a forest ecologist with NASA's Goddard Space Flight Center in Washington, D.C. KNOX: "I think this mission has tremendous potential to contribute to a better understanding of the global carbon cycle. By getting much more precise estimates of the amount of carbon that's stored in forests, we'll have a better ability to predict how much carbon is released when land is deforested, and understand the carbon balance on different continents." Scientists will calculate carbon stored in trees by first estimating the weight, called biomass, of the various forest types. They'll do that in much the same way that a doctor estimates a person's weight based on their height. Then, it's s simple matter of calculating the carbon content, says Dr. Dubayah. DUBAYAH: "So a very good approximation is that about half a tree's biomass is carbon. So if we know how tall trees are, and their vertical structure, we can make a very good estimate of what their biomass is. And then if we divide that weight by two we know their carbon content." Researchers estimate that 1.7 billion tons of carbon are released each year during forest fires intentionally set around the world. But that number may be off by as much as one billion tons. With the information provided by NASA's Vegetation Canopy Lidar satellite, Dr. Dubayah says scientists will be able to dramatically improve those estimates. That in turn will make the computer models they use to predict climate change more accurate. DUBAYAH: "Therefore we can get a much better picture of how deforestation may be adding CO2 into the atmosphere and therefore accelerating global warming." Once launched from Alaska next year, the satellite will map the world's forests over the following two years. After that, its onboard fuel cell is expected to run dry. OUTRO: This is Arctic Science Journeys, a production of the Alaska Sea Grant Program and the University of Alaska Fairbanks. I'm Doug Schneider.
Our thanksto the following individuals for their help in the preparation of this script:
Dr. Ralph Dubayah
Dr. Robert Knox If you'd like more information about the Vegetation Canopy Lidar satellite mission, or the Kodiak Rocket Launch Facility, check out these websites:
http://www.geog.umd.edu/vcl/overview.html
Arctic Science Journeys is a radio service highlighting science, culture, and the environment of the circumpolar north. Produced by the Alaska Sea Grant College Program and the University of Alaska Fairbanks.
Alaska Sea Grant Homepage The URL for this page is http://seagrant.uaf.edu/news/99ASJ/10.22.99_Deforestation.html |
 |