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WMO: Atmospheric Concentrations of Greenhouse Gases in 2005 Reach New Highs

Changes in atmospheric radiative forcing by long-lived greenhouse gases and the 2005 NOAA Annual Greenhouse Gas Index (AGGI). Click to enlarge.

In 2005, the globally averaged concentrations of the greenhouse gases carbon dioxide (CO2) and nitrous oxide (N2O) reached new highs with CO2 at 379.1 parts per million (ppm)—up 0.53% from 377.1 ppm in 2004—and N2O at 319.2 parts per billion (ppb), according to the 2005 Greenhouse Gas Bulletin, published by the World Meteorological Organization (WMO).

Methane (CH4) concentrations were unchanged at 1,783 ppb. These values are higher than those in pre-industrial times by 35.4%, 18.2% and 154.7%, respectively. After water vapor, carbon dioxide, methane (CH4) and nitrous oxide (N2O) are respectively the three most prevalent greenhouse gases in the Earth’s atmosphere.

The recently introduced NOAA Annual Greenhouse Gas Index (AGGI) shows that from 1990 to 2005 the atmospheric radiative forcing by all long-lived greenhouse gases has increased by 21.5%. The AGGI increased by 1.25% from 2004 to 2005.

Radiative forcing is the change in the balance between radiation coming into the atmosphere and radiation going out. A positive radiative forcing tends on average to warm the surface of the Earth, and negative forcing tends on average to cool the surface.

The 35.4% rise in carbon dioxide since the late 1700s has largely been generated by emissions from the combustion of fossil fuels. Around one third of N2O discharged into the air is a result of human activities such as fuel combustion, biomass burning, fertilizer use and some industrial processes.

Human activity such as fossil fuel exploitation, rice agriculture, biomass burning, landfills and ruminant farm animals account for some 60% of atmospheric CH4, with natural processes including those produced by wetlands and termites responsible for the remaining 40%.

Accurate atmospheric observations from some 44 WMO Members are archived and distributed by the World Data Centre for Greenhouse Gases (WDCGG), located at the Japan Meteorological Agency.

WMO prepares the Greenhouse Gases Bulletin in cooperation with WDCGG and the Global Atmosphere Watch Scientific Advisory Group for Greenhouse Gases with the assistance of the National Oceanic and Atmospheric Administration's Earth System Research Laboratory.




the realclimate link I gave above:
discusses the isotope thing inreadable detail. RealClimate has a stated policcy of at least trying not to get involved in the politics:
"RealClimate is a commentary site on climate science by working climate scientists for the interested public and journalists. We aim to provide a quick response to developing stories and provide the context sometimes missing in mainstream commentary. The discussion here is restricted to scientific topics and will not get involved in any political or economic implications of the science."


When will Global Warming Deniers be put on the Endangered Species list? Or are they already on it? :)


1. The rate of isotope formation is constant.
2. The only source of C12 rich carbon is coal, oil and other fossil fuels.

Think about how C14 is made (and where), and what its lifetime is.


C14 is made in the upper atmosphere and has a lifetime of 5000+ years. However in an article that I read recently, cosmic radiation exposure has been down for the last century. While radiocative decay will not have decreases C14 levels much over that time, C12 rich carbon sinks might. I'm not saying that this is the explanation, but it is a variable to consider.

Paul Dietz

C14 is made in the upper atmosphere and has a lifetime of 5000+ years. However in an article that I read recently, cosmic radiation exposure has been down for the last century.

There was also a huge pulse of 14C from the atmospheric H-bomb tests of the 50s and 60s (neutrons from the bombs made 14C by interaction with atmospheric nitrogen).


i gained a lot from this.

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