Global Carbon Dioxide Hit Record Levels in 2007

Greenhouse gases trap the Sun's radiation within the Earth’s atmosphere causing it to warm. Human activities, such as fossil fuel burning and agriculture, are major emitters of the gases, which scientists recognize as drivers of global warming and climate change.

The WMO Global Atmosphere Watch coordinates the measurement of greenhouse gases in the atmosphere through a network of observatories located in more than 65 countries. The measurements are published annually in the WMO's "Greenhouse Gas Bulletin."

FirstEnergy's Bruce Mansfield coal-fired power plant in Pennsylvania (Photo by Kiyo Komoda)

"Population growth and urban development worldwide continue to increase the use of fossil fuels, such as oil, coal and natural gas, which emit carbon dioxide and other gases into the atmosphere. At the same time, the clearing of land for agriculture, including deforestation, is releasing carbon dioxide into the air and reducing carbon uptake by the biosphere," the WMO states in its report.

The new figures were released just days ahead of the annual UN Climate Change Conference, taking place this year in Poznan, Poland from December 1-12.

It constitutes the half-way mark of a two-year negotiating process, set to culminate in an ambitious international climate change deal in Copenhagen next year that will take over from the Kyoto Protocol limiting greenhouse gas emissions, which expires in 2012.

In Poland, negotiators will take stock of the progress made in the first year of the talks and outline what needs to be done to reach agreement at the end of 2009.

Jay Gulledge, senior scientist with the Pew Center for Global Climate Change in Arlington, Virginia, says efforts to limit greenhouse gases are very recent and he would not expect to see a decrease at this point.

"The implementation of the binding phase of the Kyoto Protocol only began in 2008, that's the birth year of official efforts to reduce greenhouse gases," Gulledge told ENS in an interview. "The Kyoto Protocol is implemented separately by many countries, but very few countries have mandatory policies."

There is a voluntary, not a mandatory greenhouse gas reduction policy in the United States, which releases into the atmosphere roughly one quarter of all global greenhouse gas emissions, although it has only about four percent of the world's population.

"The most obvious mandatory policy is in the European Union," said Gulledge, "with the trading system for carbon emissions that only became binding this year. I think it is too early to judge whether we have effective policy as yet."

An ecologist who studies the carbon cycle, Gulledge says greenhouse gas emissions must peak by 2015 to have "a good shot at stabililzing the climate at a safe level."

Bushfires across Australia emitted an enormous smoke pall loaded with carbon over New South Wales, Victoria, and the adjacent South Pacific Ocean. January 2003. (Photo courtesy NASA)

After water vapor, the four most prevalent greenhouse gases in the atmosphere are carbon dioxide, methane, nitrous oxide and chlorofluorocarbons, CFCs, ozone-damaging chemicals once widely used as refrigerants.

CFC levels are now slowly dropping due to emissions reductions set under the United Nations Montreal Protocol on Substances that Deplete the Ozone Layer that entered into force in 1989.

Carbon dioxide reached 383.1 parts per million (ppm), an increase of 0.5 percent from 2006, according to the latest numbers in the World Meteorological Organization report.

Concentrations of nitrous oxide also reached record highs in 2007, up 0.25 percent from the year before.

Methane levels increased 0.34 percent, exceeding the highest value so far, which was recorded in 2003.

Using the annual greenhouse gas index issued by the U.S. National Oceanic and Atmospheric Administration, NOAA, the total warming effect of all long-lived greenhouse gases was calculated to have increased by 24.2 percent since 1990 and by 1.06 percent from the previous year.

Since the mid-18th century, carbon dioxide concentrations in the atmosphere have risen 37 percent, the WMO report shows.

Gulledge points out that greenhouse gas concentrations will continue to rise for some decades even after emissions continue to drop. "We wouldn't expect concentrations to level off until the middle of the century even with effective policy," he said.

We can expect continued warming because the heat that has already been trapped has still not all been translated into surface temperatures, he said.

"This report doesn't tell us anything directly about emissions trends," Gulledge explained. "You can measure concentrations directly. The emissions themselves are reported by individual countries, whose reliability varies. And it takes longer to compile the data."

There is a glimmer of good news concerning the greenhouse gas methane in the WMO report. While the atmospheric concentrations of other gases are increasing steadily, the growth rate of methane concentrations has slowed over the past decade, with some variations from one year to the next.

The rise of six parts per billion from 2006 to 2007 is the highest annual methane increase observed since 1998. It is still too early to state with certainty, however, that this latest increase is the start of a new upward trend in methane levels.

Human activities, such as fossil fuel exploitation, rice agriculture, biomass burning, landfills and ruminant farm animals, account for some 60 percent of atmospheric methane, with natural sources, for example wetlands and termites, responsible for the remaining 40 percent, the WMO scientists calculate.

Meanwhile, a consortium including the UN Food and Agriculture Organization said Tuesday that Africa could be absorbing more carbon dioxide from the atmosphere than the continent is releasing.

Forest in the African country of Ivory Coast (Photo courtesy Netherlands National Herbarium)

CarboAfrica found that Africa contributes less than four percent of the global emissions from fossil fuels, but accounts for 17 percent and 40 percent respectively of gas emissions emanating from deforestation and fires, according to the research conducted by scientists from 15 institutions.

The most important element is the balance between carbon captured through photosynthesis by Africa’s forests and savannas and gas released into the atmosphere, said Riccardo Valenti, coordinator of CarboAfrica.

"Our evidence so far indicates that Africa seems a 'carbon sink,' meaning that it takes more carbon out of the atmosphere than it releases," said Valenti. "If confirmed, this implies that Africa contributes to reducing the greenhouse effect, thus helping mitigate the consequences of climate change."

Copyright Environment News Service (ENS) 2008. All rights reserved.