February 20, 2009
Orbiting Carbon Observatory Aims To Boost Carbon Management Options
As the concentration of heat-trapping carbon dioxide in Earth's
atmosphere continues to rise, so also does public awareness, as well as
efforts to find solutions to this global problem. Increasing
concentrations of this potent greenhouse gas threaten to alter Earth's
climate in ways that will have profound impacts on the welfare and
productivity of society and Earth's ecosystems.
This year marks the 50th anniversary of Scripps Institution of
Oceanography scientist Charles David Keeling's Mauna Loa carbon dioxide
record, the longest continuous record of atmospheric carbon dioxide
measurements. Until now, precise ground-based measurements such as
these have been the main tool for scientists monitoring the rise of
atmospheric carbon dioxide concentrations.
Comparisons of these data with carbon dioxide emission rates from
fossil fuel combustion, biomass burning and other human activities tell
us that only about half of the carbon dioxide released into the
atmosphere during this period has remained there. The rest has
apparently been absorbed by surface "sinks" in the land biosphere or
oceans. These measurements also show that, despite the steady long-term
growth of carbon dioxide in the atmosphere, the buildup varies
dramatically from year to year, even though emissions have increased
smoothly. However, the ground-based carbon dioxide monitoring network
is too sparse to identify the locations of these sinks or tell us what
controls changes in their efficiency from year to year.
NASA's new Orbiting Carbon Observatory is designed to help meet this
need. It will measure the amount of carbon dioxide in the atmosphere
over any spot on Earth's surface and establish a record of how carbon
dioxide concentrations change over time. Observations from the mission
will improve our understanding of the carbon cycle"”the movement of
carbon among its "reservoirs" in the Earth system"”and help us
understand the influence of the carbon cycle on climate.
The observatory's ability to locate and monitor changes in carbon
sources (places where carbon is generated) and sinks (places where
carbon is absorbed or stored) will provide valuable information to
support decision making by those responsible for managing carbon in the
environment. It will assist them in developing effective strategies for
managing global carbon dioxide and monitoring the effectiveness of
Phil DeCola, a senior policy analyst in the White House Office of
Science and Technology Policy, and former Orbiting Carbon Observatory
program scientist at NASA Headquarters in Washington, said solving the
scientific mystery of the missing sinks and their curious variability
is likely to have large policy and economic impacts.
"If the nations of the world take serious action to limit the use of
fossil fuels, the right to emit carbon dioxide will become scarcer, and
emission rights would become an increasingly valuable traded
commodity," DeCola said. "Observations of the location, amount and rate
of carbon dioxide emission into the air, as well as the stock and flow
of all forms of carbon on land and in the ocean, will be needed to
manage such a world market fairly and efficiently."
Two commonly discussed strategies for reducing the amount of
atmospheric carbon dioxide are a carbon tax and a "cap-and-trade"
system. A carbon tax is a fee imposed on activities, such as burning of
fossil fuels, which emit carbon compounds into the atmosphere. The
carbon tax reduces carbon emissions by encouraging efficiencies of use,
or by alternative, non-carbon emitting processes.
Cap-and-trade systems establish limits on the carbon emissions that a
company, industry or country is allowed to produce. Those who exceed
their established limits must compensate by either purchasing emissions
rights from those whose carbon dioxide emissions fall below their
established limits, or by arranging, through contracts, for
sequestration (i.e., storage) of their excess emissions in plants,
soils or beneath Earth's surface. Effective use of either strategy
requires more accurate information on the existing sources, sinks and
fluxes of carbon dioxide, information that the Orbiting Carbon
Observatory can help provide.
"The new mission will provide information to help develop and implement
domestic policies and international collaborations to control the
movement of carbon in the environment," said Edwin Sheffner, deputy
chief of Earth Science at NASA's Ames Research Center, Moffett Field,
Calif. "By identifying and monitoring carbon sources and sinks within a
given region, the Orbiting Carbon Observatory will enable comparisons
of net carbon dioxide emission sources among regions and counties, and
will improve annual reporting of carbon budgets by industrial countries
in northern latitudes, and by tropical states with large forests."
"Future monitoring systems based on Orbiting Carbon Observatory
technology could report on regional carbon sources and sinks to verify
carbon reporting for many countries as well," he added.
Use of Orbiting Carbon Observatory data in ecosystem models may reduce
uncertainties about carbon uptake, a required part of any carbon
management effort. The mission will help clarify the quantity of carbon
dioxide being removed from the atmosphere in different geographic
regions. For example, more carbon appears to be taken up by coastal and
terrestrial ecosystems in North America than in many other parts of the
world. Orbiting Carbon Observatory observations will help determine the
specific roles that Alaska, Canada, the contiguous United States and
Mexico play in this North American carbon sink. Understanding the
relative roles of different regions will help policymakers develop the
most efficient carbon dioxide sequestration and reduction policies.
The observatory's measurements may also have direct applications for a
variety of current efforts to reduce carbon dioxide in the atmosphere.
While the mission will not be able to identify small, individual
sources of carbon dioxide emissions, it will likely be able to detect
high-emission events such as gas flares, where unwanted gas or other
materials are burned in large quantities. This ability could allow it
to verify adherence to policies aimed at reducing such flares.
Orbiting Carbon Observatory data will also have implications for land
management and agricultural practices. Plants take carbon dioxide out
of the atmosphere as they grow"”a natural type of carbon sequestration.
By repeating its measurements over multiple seasons and over regions
with different types of vegetation, such as cornfields or grasslands,
the observatory will help identify how changes in land use affect the
amount of carbon being sequestered.
Agencies such as the U.S. Department of Agriculture may base policies
for crop production and land conservation, in part, on information from
Orbiting Carbon Observatory observations, according to Sheffner.
Similar observations can be used by the Department of Energy to help
evaluate the carbon-capture potential of various biofuels and to assess
their impacts on the environment and the carbon cycle. "These findings
will influence both near- and long-term policy decisions related to
alternative energy," Sheffner added. In regions with large-scale
agricultural land cover, Orbiting Carbon Observatory-type observations
over several growing seasons could help quantify the relative roles of
different types of crops and assess the effectiveness of rangeland
management strategies in statewide carbon budget management.
Orbiting Carbon Observatory data may also prove to be an important
addition to the ongoing effort by the California Air Resources Board
and NASA scientists to improve California's database on fluctuations in
greenhouse gas emissions. "These state figures, when used to enhance
NASA ecosystem carbon models, can increase our precision and confidence
in the allocation of industrial sources of carbon dioxide emissions as
compared to emissions caused by terrestrial events such as wildfires or
crop production," Sheffner said.
Evaluation of the ocean, which takes up about one third of the carbon
humans put into the atmosphere, and its role in the global carbon
cycle, will also benefit from the new mission's observations. Orbiting
Carbon Observatory data may help show how large-scale ocean events,
such as El NiÃ±o or La NiÃ±a, affect carbon storage in the deep ocean and
in coastal regions. They may also help verify the impacts of these
events on carbon storage on the continents, such as reduced plant
growth during an El NiÃ±o-influenced drought in the U.S. Southwest.
"As the ocean absorbs large amounts of carbon dioxide, seawater becomes
more acidic, potentially threatening marine life. By monitoring changes
in the ocean's carbon uptake, the mission may shed new light on ocean
acidification and the resulting changes in ocean ecosystems," said
Sheffner. Knowing more about how ocean carbon levels fluctuate will
also help scientists evaluate the possibility of using biological or
chemical processes in the ocean to sequester carbon and perhaps even
mitigate ocean acidification.
Sheffner explained that the Orbiting Carbon Observatory may also aid
efforts to find effective ways to store excess carbon safely
underground. Combining mission data with observations from airborne and
ground-based instruments will create much more accurate maps of global
carbon sources and sinks than were ever possible before. "Once we have
a better understanding of the 'background' fluctuations in carbon
dioxide near proposed underground carbon storage sites, the
observatory's data could be useful for monitoring underground carbon
storage sites for leakage," he explained.
"The Orbiting Carbon Observatory will provide information needed for
evaluating policy options and monitoring the effectiveness of efforts
to reduce carbon emissions and increase carbon sequestration locally,
regionally and globally," Sheffner said, in summing up.
Looking to the future, DeCola said the mission will serve as a
prototype for the next generation of greenhouse gas space missions.
"The Orbiting Carbon Observatory will be an important experiment
because its results will be used to develop the future long-term,
space-based missions needed to monitor carbon dioxide for science and
decision support," he said.
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