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.

October 2009

  • Climate scientists explain why they’re sure the primary cause of global climate change today is increasing human emission of greenhouse gases — mainly carbon dioxide.
     

  • Climate scientists discuss what they know about global climate change today, and how they know it.

  • Carbon dioxide is everywhere: in the air, rising from cracks in the ocean floor, and in your soda can. Now it's showing up in the news! Find out why carbon dioxide is such a hot topic, and why it's going to be around for a long, long time.