By Deborah Gage
Posting in Environment
How high are the world's forests? And how much carbon do they store? The answer would help us figure out climate change.
An assistant professor at Colorado State University, Michael Lefsky, has combined data from three NASA satellites to produce a global map of the height of the world's forests.
Knowing how tall the forests are will help scientists figure out how much carbon the trees can capture and store and how fast they're releasing it back into the Earth's atmosphere. That data should in turn help guide policies on climate change. Lefsky will publish a paper on his work next month in Geophysical Research Letters.
The three satellites are ICESat, Terra and Aqua. Lefsky appears to have caught ICESat before the satellite's last laser failed in February and it was taken out of commission.
On July 14, NASA flight controllers finished firing ICESat's thrusters to lower its orbit so gravity can drag it back to Earth. About 90 percent of the satellite is expected to burn up in the atmosphere -- NASA claims there's little harm from the rest, although the U.S. Space Surveillance Network is supposed to be watching for debris. A second generation ICESat won't be launched before 2015.(More later on what NASA plans to do in the meantime).
ICESat was using a laser technology similar to radar, called lidar, to measure global topography, vegetation, the mass of ice sheets and the height of aersols and clouds. From NASA:
Lidar can capture vertical slices of forest canopy height by shooting pulses of light at the ground and observing how much longer it takes for light to bounce back from the surface than from the top of the forest canopy. Since lidar can penetrate the top layer of forest canopy, it provides a detailed snapshot of the vertical structure of a forest.
The data Lefsky used for his map comes from more than 250 million laser pulses from ICESat, collected over seven years. He says his alternative was counting and measuring tree trunks He filled in gaps in his data (since lidar pulses are so tiny) with data from an instrument on Terra and Aqua called MODIS which measures large-scale changes on Earth, like cloud cover and radiation, but not height.
So who has the tallest trees? From NASA:
The new results show that temperate conifer forests -- which are extremely moist and contain massive trees such as Douglas fir, western hemlock, redwoods, and sequoias -- have the tallest canopies, soaring above 131 feet. In contrast, boreal forests dominated by spruce, fir, pine, and larch had canopies typically less than 66 feet. Relatively undisturbed areas in tropical rain forests were about 82 feet tall, roughly the same height as the oak, beeches, and birches of temperate broadleaf forests common in Europe and much of the United States.
One puzzle Lefsky hopes to solve, according to NASA, is what happens to 2 billion tons per year of missing carbon dioxide, considering that humans generate 7 billion tons and the oceans and atmosphere only absorb five billion tons.
A senior scientist at the Jet Propulsion Lab, meanwhile -- Sassan Saatchi -- is relying on Lefsky's data to create forest biomass maps.
In a separate mapping project reported by the San Jose Mercury News (the tie-ins are carbon and lidar), researchers will be flying up and down the West Coast shooting light pulses to create the most detailed map of the coast yet.
That work is overseen by NOAA and is supposed to help determine how fast the Pacific Ocean is rising. It rose eight inches in the last century and could rise another 55 inches in this one if carbon dioxide-induced global warming isn't slowed
Jul 21, 2010
And most any factor that humans can be responsible for in regards to global warming is discounted by you and your cohorts. You just ignore the fact that the changes we are seeing (warming troposphere, cooling stratosphere) are characteristics of greenhouse gas driven warming. If the Sun was causing global warming the stratosphere would be warming too.
As we've previously debated through the IPCC and CRU scandals, most any factor that humankind can't possibly be responsible for is discounted in exchange for data that does.
Dude, do you seriously think climate scientists have ignored the Sun? It is the source of essentially all of the energy that drives our atmospheric. No, the reason the Sun doesn't get more attention is because its radiative emission output hasn't changed enough to account for the temperature changes observed. On top of that the pattern of warming in the atmosphere has been different* than it would be if the Sun was driving it . The Sun has been continuously monitored by satellite since around 1980. Despite the recent solar minimum being the lowest in several generations 2010 is poised to become the new record hottest year in the instrument record. The only thing that can prevent that is a strong La Nina this fall (or a very large volcanic eruption). *From current observations the troposphere has been warming but the stratosphere has been cooling a bit. If the Sun were driving global warming the stratosphere would be warming too. Stratospheric cooling is an expected signature of CO2 driven warming.
... the conspiracy to blame CO2 and take over the world for socialism is going to keep getting stronger and stronger as you folks won't ever figure out the secret of why it isn't primarily CO2. You don't have a chance. I'm just hoping if I keep posting in support they might kick a little of their ill gotten lucre my way. (For the humor impaired that was sarcasm).
The fact is that atmospheric scientists can't explain global temperatures without taking into account what the atmospheric CO2 levels are. That is as true about temperatures 500 million years ago as it is today. Volcanoes in a typical year emit less than 3% of the amount of CO2 of current human emissions. Even as large an eruption as that of Krakatoa in 1883 didn't emit as much CO2 and human currently do in a year. To do that you'd need a supervolcano like the Yellowstone caldera to erupt.
The sad fact is that more and more peope will believe in CO2 induced global warming as long as Obama is owned by Greenpease, Sierra Club, Earth Liberation Front and other "environmental Activist" groups. They will push any lie the can find to raise fear in a gullible public. I have no doubt that there is global warming, just look at the Glacier Moraines in northern Ohio and around the great lakes. I guess we are all pretty lucky the ice cap has receded. It is cycle that takes thousands of years. One good volcano puts more "greenhouse gas" into the atmosphere than we could ever do in decades.
Another false statement "..could rise another 55 inches in this one if carbon dioxide-induced global warming". There is no such thing as carbon dioxide induced global warming. As has been thoroughly covered elsewhere, CO2 is at most a very minor contributor to global warming, well behind methane and water vapor, which is one of the many reasons why rational people realize that attempts to reduce Co2 production are pointless at best, and economic murder at worst. And, the claim of massive sea level rise has by now been rather thoroughly debunked as simply false. Try and check your facts.