Navigation Links
Scientists close in on missing carbon sink

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.

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).

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 w orldwide 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 deforesta tion 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."


Source:Purdue University

Related biology news :

1. Scientists ID molecular switch in liver that triggers harmful effects of saturated and trans fats
2. Scientists Replicate Hepatitis C Virus in Laboratory
3. Scientists detect probable genetic cause of some Parkinsons disease cases
4. Scientists find missing enzyme for tuberculosis iron scavenging pathway
5. Scientists seek answers on what activates deadly anthrax spores
6. Yale Scientists Find MicroRNA Regulates Ras Cancer Gene
7. Scientists collaborate to assess health of global environment
8. Scientists decipher genome of fungus that can cause life-threatening infections
9. Scientists discover the cellular roots of graying hair
10. Scientists rid stem cell culture of key animal cells
11. Scientists develop new color-coded test for protein folding

Post Your Comments:

(Date:10/29/2015)... LA JOLLA, Calif. , Oct. 29, 2015 /PRNewswire-USNewswire/ ... released a new report titled, "DNA Synthesis and Biosecurity: ... how well the Department of Health and Human Services ... was issued in 2010. --> ... advances, but it also has the potential to pose ...
(Date:10/29/2015)... BOSTON , Oct. 29, 2015  Connected health ... phenomena driving the explosion of technology-enabled health and wellness, ... his new book, The Internet of Healthy ... apps, sensors or smartphones even existed, Dr. Kvedar, vice ... model of health care delivery, moving care from the ...
(Date:10/27/2015)... YORK , Oct. 27, 2015 In ... major issues of concern for various industry verticals such ... is due to the growing demand for secure & ... in various ,sectors, such as hacking of bank accounts, ... for electronic equipment such as PC,s, laptops, and smartphones ...
Breaking Biology News(10 mins):
(Date:11/25/2015)... ... November 25, 2015 , ... Jessica Richman and Zachary ... in their initial angel funding process. Now, they are paying it forward to ... early stage investments in the microbiome space. In this, they join other ...
(Date:11/24/2015)... 2015 /CNW/ - iCo Therapeutics ("iCo" or "the Company") ... for the quarter ended September 30, 2015. Amounts, ... and presented under International Financial Reporting Standards ("IFRS"). ... said Andrew Rae , President & CEO ... not only value enriching for this clinical program, ...
(Date:11/24/2015)... -- --> --> ... Market by Product & Services (Primer, Probe, Custom Oligos, ... End-User (Research, Pharmaceutical & Biotech, Diagnostic Labs) - Global ... expected to reach USD 1,918.6 Million by 2020 from ... 10.1% during the forecast period. Browse 183 ...
(Date:11/24/2015)... TEL AVIV, Israel , Nov. 24, 2015  Tikcro Technologies Ltd. ... be held on December 29, 2015 at 11:00 a.m. Israel ... & Co., Electra Tower, 98 Yigal Allon Street, 36 th Floor, ... , election of Eric Paneth and Izhak Tamir ... and Rami Skaliter as external directors; , approval of an ...
Breaking Biology Technology: