May 7, 2014 By Alvin Powell, Harvard Staff Writer
The world made a down payment on decades of dangerous weather last month, reaching an average atmospheric carbon dioxide level above 400 parts per million.
“No human being — ever — has witnessed this atmosphere, so breathe in deeply,” Daniel Schrag, the Sturgis Hooper Professor of Geology and the director of the Harvard University Center for the Environment, said Monday during an event at the Geological Lecture Hall.
Though daily carbon dioxide concentrations did top 400 parts per million at times last year, April marked the first time the monthly average topped that mark, reaching 401.33 ppm, according to Ralph Keeling, a Scripps Institution of Oceanography geochemist and son of the late Charles Keeling, whose “Keeling curve” alerted the world to rising carbon dioxide levels in the 1960s.
At one point during the conversation, Keeling was asked how to persuade climate change skeptics and create greater momentum for action. He called for a stronger emphasis on outreach and building trust.
“Just shouting louder doesn’t do it, they’ve already tuned us out. You don’t build trust by shouting louder.”
The event, titled “Brave New World! Entering an Age of Climate Change Beyond 400 PPM,” was sponsored by the Harvard University Center for the Environment and included a video address from former Vice President Al Gore. It came a day before a major report from the National Climate Assessment warned that climate change is already being felt across the United States — dry regions are growing drier, torrential rainstorms are increasing, heat waves and wildfires are becoming more severe, and forests are under attack from invasive pests accustomed to warmer temperatures.