Warning on greenhouse gas concentrations
23 November 2011
Global atmospheric concentrations of greenhouse gases reached record levels in 2010, according to the World Meteorological Organization (WMO). The rate of increase in their levels has also accelerated.
The WMO's Global Atmosphere Watch program coordinates systematic observations and analysis of atmospheric composition, including greenhouse gases. Measurements are taken at a network of monitoring stations in more than 50 countries around the world.
According to the latest edition of the WMO's Greenhouse Gas Bulletin, atmospheric concentrations of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) reached new highs in 2010, at 389.0 parts per million (ppm), 1808.0 parts per billion (ppb) and 323.2 ppb, respectively. These levels were 39%, 158% and 20% up on pre-1750 levels.
Between 1990 and 2010 there was a 29% increase in 'radiative forcing' - the warming effect on our climate system - from greenhouse gas emissions, the WMO said. Carbon dioxide accounted for nearly 80% of this increase. The atmospheric abundance of CO2 increased by 2.3 ppm between 2009 and 2010 - higher than the average for both the 1990s (1.5 ppm) and the past decade (2.0 ppm). The primary sources of CO2 emissions are the combustion of fossil fuels, deforestation and changes in land-use.
The WMO noted that there was a temporary relative stabilization in atmospheric concentrations of methane between 1999 and 2006, but levels have again risen. The reasons for this increase are not known, but it may have been caused by the thawing of the methane-rich northern permafrost and increased emissions from tropical wetlands. Sources of CH4 emissions include cattle-rearing, rice planting, fossil fuel exploitation and landfills.
The increasing atmospheric concentrations of nitrous oxide - mainly from the use of nitrogen-containing fertilizers - are of particular concern, the WMO said. These levels have grown at an average of about 0.75 ppb over the past decade. "Its impact on climate, over a 100 year period, is 298 times greater than equal emissions of carbon dioxide," the organization noted. "It also plays an important role in the destruction of the stratospheric ozone layer which protects us from the harmful ultraviolet rays of the sun."
WMO secretary general Michel Jarraud said, "The atmospheric burden of greenhouse gases due to human activities has yet again reached record levels since pre-industrial time." He added, "Even if we managed to halt our greenhouse gas emissions today - and this is far from the case - they would continue to linger in the atmosphere for decades to come and so continue to affect the delicate balance of our living planet and our climate."
"Now more than ever before, we need to understand the complex, and sometimes unexpected, interactions between greenhouse gases in the atmosphere, Earth’s biosphere and oceans."
In a study released in late May 2011, the International Energy Agency (IEA) said that emissions of energy-related carbon dioxide reached a new high of 30.6 billion tonnes (Gt) in 2010. The previous record was 29.3 Gt in 2008, while emissions in 2009 dipped because of the global financial crisis, it noted. In terms of fuel, some 44% of the estimated CO2 emissions in 2010 came from the burning of coal, 36% from oil, and 20% from natural gas.
Researched and written
by World Nuclear News