NOAA’s Annual Greenhouse Gas Index tracks the concentrations of greenhouse gases being added to the atmosphere principally from human-caused emissions. The AGGI then calculates the heat being added to Earth's atmosphere and oceans as a result.
This past year, for the first time since NOAA began observations, the warming influence of all these gases combined trapped the same amount of heat as an atmosphere instead containing carbon dioxide (CO2) at 500 parts per million (ppm). For thousands of years prior to 1750, the concentration of CO2 in the atmosphere was around 280 ppm.
NOAA’s index, known as the AGGI, is based on hundreds of air samples collected from sites around the world each year from NOAA’s Global Greenhouse Gas Reference Network. Each sample is carefully analyzed for numerous gases at NOAA’s Global Monitoring Laboratory in Boulder, Colorado.
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