Better Regional Monitoring Of CO2 Needed As Global
Levels Continue Rising
4/28/2008
Monitoring Earth's rising greenhouse gas levels will require a global data
collection network 10 times larger than the one currently in place in order
to quantify regional progress in emission reductions, according to a new
research commentary by University of Colorado and NOAA researchers appearing
in the April 25 issue of Science.
The authors, CU-Boulder Research Associate Melinda Marquis and National
Oceanic and Atmospheric Administration scientist Pieter Tans, said with
atmospheric carbon dioxide concentrations now at 385 parts per million and
rising, the need for improved regional greenhouse gas measurements is
critical. While the current observation network can measure CO2 fluxes on a
continental scale, charting regional emissions where significant mitigation
efforts are underway like California, New England and European countries
requires a more densely populated network, they said.
"The question is whether scientists in the United States and around the
world have what they need to monitor regional fluxes in atmospheric carbon
dioxide," said Marquis, a scientist at the Cooperative Institute for
Research in Environmental Sciences, a joint institute of CUBoulder and NOAA.
"Right now, they don't."
While CO2 levels are climbing by 2 parts per million annually a rate
expected to increase as China and India continue to industrialize effective
regional CO2 monitoring strategies are virtually nonexistent, she said.
Scientists are limited in their ability to distinguish between distant and
nearby carbon sources and "sinks," or storage areas, for example, by the
accuracy of atmospheric transport models that reflect details of terrain,
winds and the mixing of gases near observation sites.
"We are in uncharted territory as far as knowing how safe these high CO2
levels are for the Earth," she said. "Instead of tackling a very complex
challenge with the equivalent of Magellan's maps, we need to use the
equivalent of Google Earth."
Marquis and Tans propose increasing the number of global carbon measurement
sites from about 100 to 1,000, which would decrease the uncertainty in
computer models and help scientists better quantify changes. "With existing
tools we could gather large amounts of additional CO2 data for a relatively
small investment," said Marquis. "The next step is to muster the political
will to fund these efforts."
Scientists currently sample CO2 using air flasks, in-situ measurements from
transmitter towers up to 2,000 feet high and via aircraft sensors. The
authors proposed putting additional CO2 sensors on existing and new
transmitter towers that can gather large volumes of climate data. While
Europe and the United States have small networks of tall transmitter towers
equipped with CO2 instruments, such towers are rare on the rest of the
planet, she said.
Satellites queued for launch in the next few years to help monitor
atmospheric CO2 levels include the Orbiting Carbon Observatory and the
Greenhouse Gases Observing Satellite, said Marquis. The satellites will
augment ground-based and aircraft measurements charting terrestrial
photosynthesis, carbon sinks, CO2 respiration sources, ocean-atmosphere gas
exchanges and CO2 emissions from wildfires.
Mandated by the U.N. Framework Convention on Climate Change in 1994,
national emissions inventories for each country are based primarily on
economic statistics to estimate greenhouse gases entering and leaving the
atmosphere, said the authors. Such inventories are "reasonably accurate" for
estimating atmospheric CO2 from burning fossil fuels in developed countries.
But they are less accurate for other sources of CO2, like deforestation, and
for emissions of other greenhouse gases, like methane, which is emitted as a
result of rice farming, cattle ranching and natural wetlands, said the
authors.
There is a growing need to measure the effectiveness of particular
mitigation efforts by states or regions involved in pollution caps, auto
emission reduction campaigns and intensive treeplanting efforts, Marquis
said. The Western Climate Initiative, for example a consortium of seven
western U.S. states and British Columbia set a goal last year of reducing
greenhouse gas emissions by 15 percent as of 2020.
Precise regional CO2 measurements also could help chart the accuracy of
carbon trading systems involving "credits" and "offsets" now in use in
various countries around the world, said Marquis. In such systems, companies
exceeding CO2 emission caps can buy carbon credits from companies under the
caps, and groups or companies can buy voluntary carbon offsets to compensate
for personal lifestyle choices, such as airline travel.
"Independent verification through regional CO2 monitoring could help
determine whether carbon credits or offsets being bought or sold are of
value," Marquis said.
SOURCE: University of Colorado at Boulder
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