The warming influence from long-lived greenhouse gases rose again in 2017, reflecting ongoing changes to the atmosphere associated predominantly with human activities, NOAA scientists announced today. NOAA’s Annual Greenhouse Gas Index is designed to track the change in the atmosphere’s ability to absorb heat since the onset of the industrial revolution. It is based on air samples collected from a network of sites around the globe and analyzed at NOAA’s Earth System Research Lab in Boulder, Colorado.
Scientists assigned an AGGI value of 1.0 to the year 1990, which was the baseline year of the Kyoto Protocol, an international treaty calling for the reduction in greenhouse gas emissions. In 2016, the AGGI registered 1.40, reflecting a 40 percent increase in the climate-warming influence of greenhouse gases in the atmosphere since 1990. In 2017, the AGGI rose to a value of 1.41. “Greenhouse gases trap heat – it’s that simple,” said James Butler, director of NOAA’s Global Monitoring Division. “The AGGI is a single number that shows how much extra heat the atmosphere is able to trap every year.”
From NOAA Photo John Vlahakis