Annual Greenhouse Gas Index
Since 2004, researchers in NOAA’s Global Monitoring Division have released the Annual Greenhouse Gas Index to compare the total warming effect of heat-trapping gases each year to their 1990 levels. Using 1990 as a baseline, the index shows the combined warming influence from greenhouse gases—including carbon dioxide, methane, nitrous oxide, and chlorofluorocarbons—and reveals which gases contribute most to the index value each year.
The top half of the webpage provides an introduction to, and overview of, the index and the calculations used to determine results. Roughly halfway down the page you will find the annual results, which are updated each spring.
Combined global emissions of greenhouse gases increased their warming influence by about 34 percent from 1990 to 2013, with carbon dioxide by far the largest contributor to the index in terms of both amount and rate of increase. It took 240 years (from around the beginning of the Industrial Revolution) for the index to reach 100 percent, and only 24 years for it to increase by another 34 percent.
As federal regulations regarding emissions continue to evolve, having a reliable source of scientific information on the abundance of heat-trapping gases in our atmosphere is more important than ever. This is exactly what the Annual Greenhouse Gas Index provides—a connection between the scientists that study these emissions and the society that’s affected by them.