Posted on 06/22/2007 5:00:23 AM PDT by Brilliant
Scientists Close In On Missing Carbon Sink Science Daily — Forests in the United States and other northern mid- and upper-latitude regions are playing a smaller role in offsetting global warming than previously thought, according to a study appearing in Science this week. The study, which sheds light on the so-called missing carbon sink, concludes that intact tropical forests are removing an unexpectedly high proportion of carbon dioxide from the atmosphere, partially offsetting carbon entering the air through industrial emissions and deforestation.
To study the global carbon cycle, Stephens and his colleagues analyzed air samples that had been collected by aircraft across the globe for decades but never before synthesized. The team found that some 40 percent of the carbon dioxide assumed to be absorbed by northern forests is instead taken up in the tropics.
"Our study will provide researchers with a much better understanding of how trees and other plants respond to industrial emissions of carbon dioxide, which is a critical problem in global warming," Stephens says. "This will help us better predict climate change and identify possible strategies for mitigating it."
The missing carbon
For years, one of the biggest mysteries in climate science has been the question of what ultimately happens to the carbon emitted by motor vehicles, factories, deforestation, and other sources. Of the approximately 8 billion tons of carbon emitted each year, about 40 percent accumulates in the atmosphere and about 30 percent is absorbed by the oceans. Scientists believe that terrestrial ecosystems, especially trees, take up the remainder.
To find this terrestrial carbon sink, scientists have turned to computer models that combine worldwide wind patterns with measurements of carbon dioxide taken just above ground level. The models indicate that northern forests absorb about 2.4 billion tons per year. However, ground-based studies have tracked only about half that amount, leaving scientists to speculate about a "missing carbon sink" in the north.
Stephens and his collaborators set out to test how well the models captured carbon sinks, focusing in particular on estimates produced by a recent international study into global carbon exchange known as TransCom. They turned to flasks of air collected by research aircraft over various points of the globe for the past 27 years. The air samples had been analyzed by several labs around the world, which used them to investigate various aspects of the carbon cycle, but this was the first time that a team of scientists analyzed them to obtain a picture of sources and sinks of carbon on a global level.
The research team compared the air samples to estimates of airborne carbon dioxide concentrations generated by the computer models. The scientists found that most of the models significantly underestimated the airborne concentrations of carbon dioxide in northern latitudes, especially in the summer, when plants take in more carbon. The aircraft samples show that northern forests absorb only 1.5 billion tons of carbon a year, which is almost 1 billion tons less than the estimate produced by the computer models.
The scientists also found that intact tropical ecosystems are a more important carbon sink than previously thought. The models had generally indicated that tropical ecosystems were a net source of 1.8 billion tons of carbon, largely because trees and other plants release carbon into the atmosphere as a result of widespread logging, burning, and other forms of clearing land. The new research indicates, instead, that tropical ecosystems are the net source of only about 100 million tons of carbon, even though tropical deforestation is occurring rapidly.
"Our results indicate that intact tropical forests are taking up a large amount of carbon," Stephens explains. "They are helping to offset industrial carbon emissions and the atmospheric impacts of clearing land more than we realized."
Capturing vertical movements
Most of the computer models produced incorrect estimates because, in relying on ground-level measurements, they failed to accurately simulate the movement of carbon dioxide vertically in the atmosphere. The models tended to move too much carbon dioxide toward ground level in the summer, when growing trees and other plants take in the gas, and not enough carbon dioxide up in the winter. As a result, scientists believed that there was relatively less carbon in the air above mid-latitude and upper-latitude forests, presumably because trees and other plants were absorbing high amounts.
Conversely, scientists had assumed a large amount of carbon was coming out of the tropics and moving through the atmosphere to be absorbed in other regions. But the new analysis of aircraft samples shows that this is not the case.
"With this new information from aircraft samples we see that the models were overestimating the amount of uptake in the north and underestimating uptake in the tropics," says Kevin Gurney of Purdue University, a co-author of the paper and coordinator of the TransCom study. "To figure out exactly what is happening, we need improved models and more atmospheric observations."
The Science article, "Weak northern and strong tropical land carbon uptake from vertical profiles of atmospheric CO2," was written by an international team of scientists led by Britton Stephens of the National Center for Atmospheric Research (NCAR).
The research team comprised scientists from Colorado State University, Purdue University, and the National Oceanic and Atmospheric Administration in the United States; as well as from the Laboratory of Climate Science and the Environment (France), Tohoku University, National Institute for Environmental Studies, and Nagoya University (Japan), Central Aerological Observatory and Sukachev Institute of Forest (Russia), University of Leeds (United Kingdom), Max Planck Institute for Biogeochemistry (Germany), and CSIRO Marine and Atmospheric Research (Australia).
Authors were Britton B. Stephens, Kevin R. Gurney, Pieter P. Tans, Colm Sweeney, Wouter Peters, Lori Bruhwiler, Philippe Ciais, Michel Ramonet, Philippe Bousquet, Takakiyo Nakazawa, Shuji Aoki, Toshinobu Machida, Gen Inoue, Nikolay Vinnichenko, Jon Lloyd, Armin Jordan, Martin Heimann, Olga Shibistova, Ray L. Langenfelds, L. Paul Steele, Roger J. Francey, A. Scott Denning.
“To figure out exactly what is happening, we need improved models and more atmospheric observations.”
But Al Gore says we already know what is happening and we’re all doomed.
Winston Churchill, if alive today, would have issued this quote: "Never have so many been wrong about so much..."
Maybe the models are wrong in their many assumptions.
That’s an interesting article. But the many references to “computer models” as though they were living oracles bother me. Computer models are merely tools. If someone using a computer model finds that it gives results that differ from measured results, then the computer model is simply wrong in one or many aspects. Computer models don’t tell you anything. People who use computer models may have opinions based on those models.
Say what? Did you mean “Global Warming is the result of the Sun warming the Earth, not the result of carbon dioxide”?
Growing more forests in United States could contribute to global warming (Save Earth! Cut trees!)
Lawrence Livermore National Laboratory ^ | December 5, 2005 | Lawrence Livermore National Laboratory
http://www.freerepublic.com/focus/f-news/1534904/posts
Whooops. So are the carbon credit companies going to have to find some other way than (supposedly) planting a tree when you (or the US House of Representatives) buy an offset?
Just noting this study is quoting NET absorption.
Vegetation takes in about 62 billion tons of carbon each year and releases 60 billion tons back. Oceans have similar numbers with 92 billion going in and 90 billion being released.
Those figures can be compared to human emissions which are about 7.5 billion tons a year right now. So trees and oceans are absorbing on a net basis about 4.0 billion of the 7.5 billion tons of carbon we are releasing each year but the totals involved in the carbon cycle dwarf human figures. It is just that we are adding more to a system which was more-or-less in balance. That could change however.
If anyone has a link to the study, or access to Science magazine, I’d be interested in the actual CO2 concentration figures they measured in this study.
The missing carbonFor years, one of the biggest mysteries in climate science has been the question of what ultimately happens to the carbon emitted by motor vehicles, factories, deforestation, and other sources. Of the approximately 8 billion tons of carbon emitted each year, about 40 percent accumulates in the atmosphere and about 30 percent is absorbed by the oceans. Scientists believe that terrestrial ecosystems, especially trees, take up the remainder.
Missing Carbon?!? Small potatoes.
90% of the Universe is missing. Ponder that you 'climate science' guys (Oh, and get a real job).
Actually he is just an oxygen load. Nothing moore.
It’s even worse than that..
People who WRITE computer models HAVE opinions based on those models that they write, and get MORE money FROM those computer models when they write computer models that make results that the get those funds.
I’m being cynical of course: but re-read the baseline article to see HOW MANY assumptions proved wrong by how many hundreds of times: 1.8 BILLION assumed tons becomes merely one million tons... Vertical paths were ignored.
30% of the carbon emitted by man (in TODAY’S emissions!) is “lost” yet the enviro’s are demanding that we crash the economy to reduce emissions by 2% ?
“human emissions...”
I would think that as long as the world’s population is growing (and not getting skinnier), the net human emissions are negative. Maybe that’s where the sink is.
During the day when the Sun is overhead, it seems to get warmer; when the Sun is gone it gets cooler.
I think you may have come up the smoking gun; the Sun is the cause of Global Climate change.
Bingo!! We have a winner!!
“Net Human emissions” =
- 1/100th of the total population dies each year, 70 million people, at 150 pounds (.07 tons), with 20% of that Carbon by weight, equals net human absorption of carbon buried each year in graves...
= Only 1 million tons. LOL.
Actually, when it's winter in the northern hemisphere, the earth is closer to the sun than it is in the summer. It's just that because of the tilt of the earth, the sun's rays hit more directly in the northern hemisphere during the summer. Southern hemisphere seems to have more extreme temperatures -- when the earth is closer to the sun, they're getting the direct summer rays, and vice versa.
Of course, most of what I know about southern hemisphere temperatures is from reading The Thorn Birds years ago! ;-)
Methane.
He’s a methane load.
They don’t have to die, though. As long as the aggregate weight of the carbon incorporated into human beings is increasing, that’s carbon that won’t be in the atmosphere.
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