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How Fast Can Plants Absorb Our Carbon Emissions? UC Merced Professor Develops New Photosynthesis Measurement Method

November 14, 2008

MERCED - We count on vegetation to absorb a large portion of the
carbon dioxide emitted from the burning of fossil fuels, helping
mitigate climate change through photosynthesis. But what happens if
the temperature warms enough to change that process? Heat, drought
or a shift from snowfall to rainfall caused by climate warming may
affect the amount of CO2 absorbed through photosynthesis by
vegetation, but how much?

“Our inability to accurately measure and forecast photosynthesis
has been responsible for a big part of the uncertainty in our
climate change forecasting so far,” said

Professor Elliott Campbell
of the University of California, Merced.


new study by Campbell and several colleagues in today’s issue of
the journal Science
outlines a method for measuring
photosynthesis by quantifying the relationship between CO2 and
another form of carbon, carbonyl sulfide, or COS, in the
atmosphere. His results - obtained in collaboration with fifteen
other scientists from around the United States and other countries
- will allow accurate information about photosynthesis to be
incorporated into major climate models, helping make climate change
forecasts much more reliable.

“Professor Campbell’s discovery represents a workable way to
measure photosynthesis and a major contribution to climate change
science,” said Dean Jeff Wright of the
UC Merced School of
“The publication of his new paper in Science is a
great accomplishment for him and his colleagues worldwide, and a
source of pride for our campus.”

Campbell found himself spotlighted in media outlets nationwide
last year upon the announcement of his research finding that we
could meet up to 8 percent of our energy needs by using sustainably
produced biofuels - fuels made from crops grown on abandoned
farmland, for example.

His new work may have an even bigger impact.

COS is used by plants, in a process parallel to photosynthesis,
at about the same rate CO2 is used in photosynthesis. Using COS to
measure photosynthesis is more straightforward than using CO2,
because while plants do absorb CO2, they also emit it.

The Science study places observed data on North American
atmospheric COS and CO2, as well as information gleaned from
laboratory experiments, into a 3-D computer model, showing that
plants draw COS down from the atmosphere and providing evidence
that the relationship between COS and CO2 measurements indicate the
rate of photosynthesis.

Campbell said the method he and his colleagues have devised may
now be used to analyze large atmospheric carbon datasets assembled
by the North American Carbon Program through the National Oceanic
and Atmospheric Administration (NOAA) and NASA. Resulting
information can be used to refine or even correct the models we now
rely on to predict what will happen to our climate in the future.

UC Merced is rapidly establishing itself as a center for climate
change research. The Sierra Nevada Research Institute, an
interdisciplinary research organization on campus focusing on
resource-related research in the Sierra Nevada and the neighboring
Central Valley of California, houses major projects investigating
precipitation, water supplies, species habitats and more issues
hinging on what happens in Earth’s warming climate. The UC Merced
Energy Research Institute emphasizes research aiming at
energy-related approaches to mitigating climate change - solar
energy, biofuels, and other sustainable solutions. Campbell is a
participating faculty member in both institutes.

The research for this paper was conducted before Campbell
arrived at UC Merced earlier this year.

The Science abstract for Campbell’s paper can be found online at⅖904/1085
Subscribers to the journal can read the entire text online.

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