Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Land plants process 15 percent of total atmospheric carbon dioxide each year

06.07.2010
Terrestrial ecosystems draw about 123 billion tonnes of carbon (450 billion tonnes of carbon dioxide, CO2) from the atmosphere each year. Based on worldwide local measurements and data-driven model simulations, an international team of researchers led by Christian Beer of the Max Planck Institute for Biogeochemistry in Jena has for the first time provided an observation-based estimate of the largest global flux of carbon between land and atmosphere and of its climate dependencies.

The researchers evaluated the result against spatially explicit process models including the leading model LPJmL from PIK. Tropical ecosystems such as rain forests and savannas account for almost two thirds of the CO2 uptake, they report in an article published by the journal “Science” on the “Science Express” web site today.


The canopy of the Ankasa tropical forest, in Ghana, Africa, picture taken from a flux tower.
Credit: Carboafrica, www.carboafrica.net

“Our results confirm the major role of rainfall for the global carbon cycle: It controls plant uptake of CO2 for over forty percent of all vegetated land,” says Alberte Bondeau of the Potsdam Institute for Climate Impact Research (PIK), who contributed computer simulations of global vegetation to the study. Patterns of precipitation are expected to undergo substantial changes with global warming. “This could profoundly affect the productivity of land ecosystems,” Bondeau notes.

The researchers used information from a global network of observation stations to quantify the exchange of CO2 between different ecosystems and the atmosphere. More than 250 observation towers provide continuous measurements. The team used these data to train diagnostic computer models which were then used to compute the value of total worldwide uptake of CO2 by vegetation, the so-called gross primary production of the terrestrial biosphere.

The value of ca. 450 billion tonnes per year describes the total volume of fixation of CO2 in the process of photosynthesis on land and is a function of environmental conditions, particularly of climate variables and vegetation properties. The carbon removed from the atmosphere in this manner later returns to it on various time scales: a large fraction returns quickly due to plant respiration, another large fraction more slowly when leaves decay or woody material decomposes in the soil, or through wildfires. The delay in the return of some of the CO2 fixed by plants to the atmosphere is an important factor controlling the rate of climate change due to human emissions.

Despite its central importance to the global carbon cycle, the study now published is the first to constrain global CO2 intake by vegetation with reasonable confidence. It confirms the prominent role of tropical vegetation in the land carbon cycle and points to a strong relationship between CO2 uptake and precipitation for extended regions of the world.

The research team also compared the observation-based estimate to the results of process-oriented computer models of global ecosystems. Such models are used to assess the future development of the land carbon balance under climate change. Both versions of the model developed at PIK, one for global potential natural vegetation (LPJ) and one including the effects of worldwide agricultural land use (LPJmL) were studied.

The findings show that currently available process models reproduce latitudinal differences in carbon uptake by land vegetation but differ in the simulated magnitude and variation of the process and overestimate the precipitation effect on the gross CO2 uptake. This indicates that additional mechanisms, e.g. adaptation, may serve to attenuate the vegetation response to climate. PIK's LPJmL model, which takes into account the effects of agriculture and especially irrigated croplands, correctly reproduced a reduced sensitivity of carbon uptake to precipitation, though it remains an important climatic factor. The exact causes of the mechanism deserve further study.

“These results are hugely important: They take our understanding of the role of the land surface in climate regulation through CO2 exchange and of global biomass production to the next level. In terms of our ability to model the future, we are on much more solid grounds now,” says Wolfgang Lucht, Co-Chair of PIK’s Department of Climate Impacts and Vulnerability. “The numbers show that amazingly, every seven years all of the carbon dioxide contained in the atmosphere flows once through the world’s leaves. It is one of the most important processes on the planet and we now have a reliable estimate of the magnitude of this flux.”

Article: Beer, C., M. Reichstein, E. Tomelleri, P. Ciais, M. Jung, N. Carvalhais, C. Rödenbeck, M. Altaf Arain, D. Baldocchi, G. B. Bonan, A. Bondeau, A. Cescatti, G. Lasslop, A. Lindroth, M. Lomas, S. Luyssaert, H. Margolis, K. W. Oleson, O. Roupsard, E. Veenendaal, N. Viovy, C. Williams, I. Woodward, and D. Papale, 2010: Terrestrial Gross Carbon Dioxide Uptake: Global Distribution and Co-variation with Climate. Published within the “Science Express” web site: http://www.sciencemag.org/sciencexpress/recent.dtl

Patrick Eickemeier | PIK Potsdam
Further information:
http://www.fluxdata.org -
http://www.carboafrica.net/index_en.asp

More articles from Ecology, The Environment and Conservation:

nachricht Dispersal of Fish Eggs by Water Birds – Just a Myth?
19.02.2018 | Universität Basel

nachricht Removing fossil fuel subsidies will not reduce CO2 emissions as much as hoped
08.02.2018 | International Institute for Applied Systems Analysis (IIASA)

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Attoseconds break into atomic interior

A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.

In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...

Im Focus: Good vibrations feel the force

A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.

By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Basque researchers turn light upside down

23.02.2018 | Physics and Astronomy

Finnish research group discovers a new immune system regulator

23.02.2018 | Health and Medicine

Attoseconds break into atomic interior

23.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>