 |
|
Smithsonian scientists report new carbon dioxide study
March 13, 2007Increased atmospheric CO2 stimulates soils to release, not store, CO2
Researchers at the Smithsonian Environmental Research Center report the results of a six-year experiment in which doubling the atmospheric greenhouse gas carbon dioxide (CO2) in a scrub oak ecosystem caused a reduction in carbon storage in the soil.
The scientists said this response suggests a limited capacity of Earth's ecosystems to stabilize atmospheric CO2 and slow global warming. These findings add a new perspective and a measure of caution suggesting that elevated CO2, by altering microbial communities, may turn a potential carbon sink into a carbon source.
Previous studies have shown that plants will respond to higher CO2 by increasing growth and taking up much of the excess carbon. This has led some to speculate that plants may be able to mitigate increases in atmospheric CO2 and that soils, which represent the largest and most stable terrestrial carbon pool, also may serve as a sink for excess carbon.
During the course of their study, Smithsonian scientists saw a consistent loss in soil carbon under high CO2 conditions. The CO2 loss from soils offset about 52 percent of the additional carbon that had accumulated in the plants above ground and in the roots.
"We were surprised to find that these soils were losing soil carbon despite the fact that there was more plant growth," said Patrick Megonigal, a microbial ecologist at SERC and one of the study's authors. "We thought that higher plant growth at elevated CO2 would either add more carbon to soils, or at least leave it the same. We now need to consider a third possibility—the carbon already in soils will end up back in the atmosphere as a greenhouse gas."
The study will be published this week in Proceedings of the National Academy of Sciences.
Working at a long-term Smithsonian experimental CO2 site in a Florida scrub oak ecosystem, the researchers compared core samples from test plots that had been exposed to six years of elevated CO2 and core samples from plots exposed to ambient CO2. They also performed laboratory experiments on soils from both elevated and ambient plots to understand microbial composition and activity within each type of soil.
Their study reveals that added CO2 has a so-called "priming effect," stimulating certain microbes and increasing decomposition. Soils exposed to the elevated CO2 had higher relative abundances of fungi and higher activities of a soil carbon-degrading enzyme. As the fungi and enzymes decompose the organic matter in the soil, they free up stored carbon and release it through respiration as CO2. With the priming effect of added CO2, more soil decomposition results in higher respiration rates, an overall loss of carbon and an increase in the release of CO2 from the soil.
Smithsonian
Previous studies have shown that plants will respond to higher CO2 by increasing growth and taking up much of the excess carbon. This has led some to speculate that plants may be able to mitigate increases in atmospheric CO2 and that soils, which represent the largest and most stable terrestrial carbon pool, also may serve as a sink for excess carbon.
During the course of their study, Smithsonian scientists saw a consistent loss in soil carbon under high CO2 conditions. The CO2 loss from soils offset about 52 percent of the additional carbon that had accumulated in the plants above ground and in the roots.
"We were surprised to find that these soils were losing soil carbon despite the fact that there was more plant growth," said Patrick Megonigal, a microbial ecologist at SERC and one of the study's authors. "We thought that higher plant growth at elevated CO2 would either add more carbon to soils, or at least leave it the same. We now need to consider a third possibility—the carbon already in soils will end up back in the atmosphere as a greenhouse gas."
The study will be published this week in Proceedings of the National Academy of Sciences.
Working at a long-term Smithsonian experimental CO2 site in a Florida scrub oak ecosystem, the researchers compared core samples from test plots that had been exposed to six years of elevated CO2 and core samples from plots exposed to ambient CO2. They also performed laboratory experiments on soils from both elevated and ambient plots to understand microbial composition and activity within each type of soil.
Their study reveals that added CO2 has a so-called "priming effect," stimulating certain microbes and increasing decomposition. Soils exposed to the elevated CO2 had higher relative abundances of fungi and higher activities of a soil carbon-degrading enzyme. As the fungi and enzymes decompose the organic matter in the soil, they free up stored carbon and release it through respiration as CO2. With the priming effect of added CO2, more soil decomposition results in higher respiration rates, an overall loss of carbon and an increase in the release of CO2 from the soil.
Smithsonian
Carbon Dioxide Current Events and Carbon Dioxide News RSSGas from the past gives scientists new insights into climate and the oceans
In recent years, public discussion of climate change has included concerns that increased levels of carbon dioxide will contribute to global warming, which in turn may change the circulation in the earth's oceans, with potentially disastrous consequences.
Emissions rising faster this decade than last
The latest figures on the global carbon budget to be released in Washington and Paris today indicate a four-fold increase in growth rate of human-generated carbon dioxide emissions since 2000.
Green coffee-growing practices buffer climate-change impacts
Chalk up another environmental benefit for shade-grown Latin American coffee: University of Michigan researchers say the technique will provide a buffer against the ravages of climate change in the coming decades.
Cranking up the volume-- Sounds travel farther underwater as world's oceans become more acidic
It is common knowledge that the world's oceans and atmosphere are warming as humans release more and more carbon dioxide into the Earth's atmosphere. However, fewer people realize that the chemistry of the oceans is also changing--seawater is becoming more acidic as carbon dioxide from the atmosphere dissolves in the oceans.
Carbon sinks: Issues, markets, policy
With reducing carbon emissions on the national agenda, a group of expert panelists will discuss methods, markets, testing and policy issues on how carbon sinks or carbon sequestration may be used to reduce atmospheric CO2.
Metal-organic frameworks feel the pressure of Argonne scientists
Scientists at U.S. Department of Energy's Argonne National laboratory are putting the pressure on metal-organic frameworks (MOF).
International Field Campaign examines impact of beetle kill on Rocky Mountain weather, air quality
Mountain pine beetles appear to be doing more than killing large swaths of forests in the Rocky Mountains. Scientists suspect they are also altering local weather patterns and air quality.
Pine Bark Beetles Affecting More than Forests
Pine bark beetles appear to be doing more than killing large swaths of forests in the Rocky Mountains. Scientists suspect they are also altering local weather patterns and air quality.
CO2 emissions booming, shifting east, researchers report
Despite widespread concern about climate change, annual carbon dioxide emissions from burning fossil fuels and manufacturing cement have grown 38 percent since 1992, from 6.1 billion tons of carbon to 8.5 billion tons in 2007.
Modest CO2 cutbacks may be too little, too late for coral reefs
How much carbon dioxide is too much? According to United Nations Framework Convention on Climate Change (UNFCCC) greenhouse gases in the atmosphere need to be stabilized at levels low enough to "prevent dangerous anthropogenic interference with the climate system." But scientists have come to realize that an even more acute danger than climate change is lurking in the world's oceans-one that is likely to be triggered by CO2 levels that are modest by climate standards.
More Carbon Dioxide Current Events and Carbon Dioxide News Articles
| The Carbon Dioxide Syndrome by Jennifer Stark and Russell Stark Learn why changing your breathing can improve your health and well-being through the Butekyo Method. This method will help those with sleep disorders, panic attacks, allergies, hypertension and... | |
 | 21st Century Essential Guide to Carbon Sequestration: Greenhouse Gas and Carbon Dioxide Capture and Pollution Control to Prevent Global Warming, Coal Power Plant Research (CD-ROM) by U.S. Government This unique electronic book on two CD-ROMs has the finest collection of federal documents and resources available anywhere about carbon sequestration, capturing carbon dioxide emissions from coal-fired power plants to help prevent global warming from greenhouse gases. The Department of Energy’s National Energy Technology Laboratory (NETL) manages laboratory and field R&D focused on technologies... |
 | Chemical Fixation of Carbon Dioxide: Methods for Recycling CO2 into Useful Products by Martin M. Halmann Chemical Fixation of Carbon Dioxide presents new concepts and results from research into the problems caused by increasing levels of carbon dioxide. The book discusses the limitations of natural plant photosynthesis as a sink for carbon dioxide and emphasizes chemical fixation as an important alternative. A number of significant topics are covered, including new coupling reactions for producing... |
 | Harnessing Farms and Forestsin the Low-Carbon Economy: How to Create, Measure, and Verify Greenhouse Gas Offsets by Nicholas Institute for Environmental Policy Solutions As the United States moves to a low-carbon economy in order to combat global warming, credits for reducing carbon dioxide emissions will increasingly become a commodity that is bought and sold on the open market. Farmers and other landowners can benefit from this new economy by conducting land management practices that help sequester carbon dioxide, creating credits they can sell to industry to... |
 | The Carbon Dioxide Dilemma: Promising Technologies and Policies by National Academy of Engineering, National Research Council Growing concerns about climate change partly as a result of anthropogenic carbon dioxide emissions has prompted the research community to assess technologies and policies for sequestration. This report contains presentations of a symposium held in April of 2002. The sequestration options range form ocean disposal, terrestrial disposal in geologic formations, biomass based approaches and carbon... |
 | Greenhouse Gas Carbon Dioxide Mitigation: Science and Technology by Martin M. Halmann, Meyer Steinberg Any mention of the "greenhouse effect" tends to ignite controversy. While the rising atmospheric concentrations of greenhouse gases-especially carbon dioxide- are certainly among the most pressing issues today, theoretical and perceived consequences have been subject to conjecture and misinformation. That raging debate has obscured an important fact: scientists and engineers are hard at work on... |
 | Solubility in Supercritical Carbon Dioxide by Ram B. Gupta, Jae-Jin Shim Supercritical fluid extraction is an environmentally safe and cost-effective alternative to traditional organic solvents. Carbon dioxide is widely used as the solvent of choice for applications such as caffeine and nicotine extraction due to its mild critical temperature, nontoxicity, nonflammability, and low cost. Introducing the most complete collection of supercritical CO2 solubility data... |
 | Carbon Dioxide Capture and Storage: Special Report of the Intergovernmental Panel on Climate Change by IPCC This IPCC Special Report describes sources, capture, transport, and storage of CO2. It discusses the costs, economic potential, and societal issues of the technology, including public perception and regulatory aspects. Storage options evaluated include geological storage, ocean storage, and mineral carbonation. The report places CO2 capture and storage in the context of other climate change... |
 | Carbon Capture and Sequestration Integrating Technology, Monitoring, Regulation This book is the first systematic presentation of the technical, legal, and economic forces that must coalesce to realize carbon dioxide capture and geologic sequestration as a viable CO2 reduction strategy. It synthesizes key engineering data and explains the technological and legal conditions that must be in place for carbon sequestration to be... |
| The Survival of Civilization Depends Upon Our Solving Three Problems: Carbon Dioxide, Investment Money and Population - Selected Papers of John D. Hamaker by John D. Hamaker, Donald A. Weaver |
| © 2008 BrightSurf.com |