2.9 ppmv increase
in CO2 atmospheric concentration from
1997 to1998 observed at the Mauna Loa Observatory in Hawaii is the largest
annual increase since measurements began in 1958.
In addition to whatever climate changes (global warming, regional climate
changes, accelerated sea-level rise) may be caused by increasing atmospheric
CO2, it is known that atmospheric
CO2 directly affects plant photosynthesis
and water use, thereby potentially affecting vegetation and ecosystems, both
managed and unmanaged (e.g., crops and forests). Analyzing the responses of
vegetation and ecosystems to such increasing concentrations of
CO2 in the atmosphere is a key component
of global change research. Numerous CO2
-enrichment studies in greenhouses, growth chambers, and open-top chambers
have suggested that growth of many plants could increase about 30% on average
with a doubling of the atmospheric CO2
concentration, in the short-term (up to a few years, to most). However,
the applicability of such work to the growth of plants outdoors, under
natural conditions and for longer periods, has been seriously questioned.
The free-air CO2 enrichment (FACE) approach
represents the state of the science in exposing plants and ecosystems to
levels of atmospheric CO2 that may be
reached during the coming 50 years. The approach eliminates many of the more
significant limitations inherent in greenhouse and chamber systems, especially
for large/tall vegetation such as trees. Information from FACE research on
how crop, forest, and other ecosystems will react can help anticipate the
impacts (both positive and negative) of future global change. Will there be
changes in the rate at which crops and trees grow over the next hundred years?
Will the storage of carbon aboveground and belowground (including soils) change?
Could feedbacks from carbon storage in terrestrial ecosystems alter global
atmospheric CO2 concentrations?
FACE research facilities provide a platform
from which to seek answers to these and many more questions concerning the
response of ecosystems to increasing atmospheric CO2
concentrations.
CDIAC
Oak Ridge National Laboratory
(865) 574-0390
(865) 574-2232 (FAX)
cdiac@ornl.gov
Data and Information Requests: (865) 574-3645
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