The Issue
The carbon dioxide (CO2) concentration in the atmosphere has increased by nearly
30 percent since the industrial revolution and many scientists believe that, as
a result, the earth's climate is already warmer and more prone to extreme
events. Could terrestrial ecosystems slow down the build up of carbon dioxide in
the atmosphere and the rate of climate change? Eight hundred of the world's
leading environmental scientists will address this and other questions at a
meeting sponsored by GCTE/LUCC in Barcelona, Spain, on March 14-18, 1998.
The Science
- Indirect evidence suggests that terrestrial ecosystems are already slowing
down climate change by absorbing about one third of our annual CO2 emissions.
Dr. Christian Körner, from the University of Basel, Switzerland, will stress
that one of the important goals of GCTE research is to document carbon storage
in a variety of ecosystems. He will show that ecosystem?s carbon storage is the
result of complex interactions between plants (which use CO2 for
photosynthesis), soils and the organisms that decompose dead plant material.
- Two recent technological developments will be presented. These developments
improve our ability to study carbon storage at the ecosystem level. First, Free
Air CO2 Enrichment technology (FACE) allows scientists to expose large areas of
intact ecosystems to elevated CO2 concentrations. At present, 16 such
experiments involving 24 sites are going on worldwide. Dr. W. Schlesinger and
Dr. E. DeLucia (Duke University and University of Illinois) will show that a
loblolly pine forest ecosystem which has been growing at one and a half time the
current CO2 concentration since 1996, is so far storing about 20% more carbon
when exposed to elevated CO2. Second, eddy covariance technology can be used to
measure how much carbon dioxide is absorbed by ecosystems over areas exceeding
one square kilometer. R. Valentini, University of Tuscia, Italy, will review the
results of a world-wide network of eddy-covariance towers, and in particular of
Euroflux, a network of ten towers in temperate
and boreal regions of Europe. These results indicate that forests in the
temperate zone of Europe are presently storing carbon. Dr. Steve Pacala,
Princeton University, USA, estimates, based on a model of atmospheric and
oceanic CO2 concentrations, that temperate regions of North America are also
currently storing carbon.
- R. Scholes, CSIR, South Africa will, however, argue that current terrestrial
ecosystems may be close to their upper limit in terms of carbon storage capacity
and might not help us further as we keep pumping CO2 into the atmosphere.
Moreover, the vegetation changes that will take place as temperature increases
are likely to result in high carbon emissions because carbon will be released as
plants die and are replaced by new species. Models of the earth?s vegetation -
based on a comparative study by Dr W. Cramer and colleagues (Potsdam Institue
for Climate Change Impact, Germany) - also indicate that terrestrial ecosystems
should reach their limit for storing additional carbon by 2050.
On March 16, Session 1 and 3 will address various topics related to carbon fluxes in terrestrial ecosystems and their capacity for long term carbon storage. In addition, a plenary session will be devoted to this topic ("The Nature of Earth: Source or Sink for Carbon") on March 18 at 9.20, and various ad hoc meetings throughout the Conference will address the use of carbon and oxygen isotopes, FACE experiments, and modeling to study carbon fluxes and its controls under global change. Many posters on this topic will be exhibited during the poster sessions of March 16 and 17, and oral posters will be presented during March 16 in the afternoon.
Université Paris-Sud, Ecologie des Populations et Communautes, Bat. 362,
F-91405 Orsay Cedex, France
Phone/Fax: +33 1 69 15 56 92/6
E-mail: anne.larigauderie@epc.u-psud.fr
Conference Secretatiat, Barcelona, Spain:
Tel: +34 3 233 2387 FAX: +34 3 233 2575