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.

December 2009

  • Has global warming stopped? That's what some people claim, based on global temperatures recorded since 1998. But, scientists say, not setting a new record high temperature each year doesn't mean the globe is cooling.