Climate Change & Global Warming

The annual average concentration of carbon dioxide (CO2) in the atmosphere stood at 395.3 parts per million (ppm) in 2013—a 27 percent increase compared to conditions before the Industrial Revolution. On May 9, 2013, the daily average concentration of CO2 surpassed 400 ppm for the first time at the Mauna Loa Observatory in Hawaii.

May 2012

  • NOAA scientists have documented a new impact of the increasingly thin blanket of Arctic sea ice: gases escaping from the thinner ice in spring are affecting air chemistry, reducing ground-level ozone, and likely increasing mercury contamination.