Global average CO2 concentrations since 2004 (monthly values in red, long-term trend in black). Click here to enlarge. Credit: NOAA
The National Oceanic and Atmospheric Administration announced last week that increases in two major greenhouse gases accelerated in 2007.
Carbon dioxide (CO2), the primary contributor to global warming, increased by 0.6%, which represents an addition to the atmosphere of 19 billion tons, or 2.4 parts per million (ppm). This brings the total atmospheric concentration to about 385 ppm, an increase of 37.5% from the pre-industrial level of 280 ppm prior to 1850. The annual increases of 2 ppm -- common since 2000 -- are up from 1.5 ppm annually in the 1980s and less than 1 ppm per year in the 1960s.