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.

April 2010

  • Curiosity is a cruel master, says Dave Bertelsen. Over the past 25 years, he has hiked over 12,000 miles through a desert canyon, just to see what was blooming. He found a few surprises along the way.