June 5, 2009
Combustion of coal, oil, and natural gas has been increasing the concentrations of climate-warming (greenhouse) gases in the atmosphere since the start of the Industrial Revolution. Past emissions have initiated warming of about 0.1 to 0.2ºC per decade over the last few decades, while at the same time causing retreat of Arctic sea ice, melting back of snow cover and glaciers, more frequent occurrence of very heavy precipitation, intensification of severe storms, rising sea level, and shifts in the natural ranges of plants and animals. Without limits on emissions, much greater change will occur during the 21st century, including setting the world on a path to sea level rise of many feet, or even meters, over the next few centuries. To limit the most adverse consequences, society needs to shift away from energy technologies that release carbon dioxide, methane, and other greenhouse gases—and do this over the next several decades.
Michael C. MacCracken is Chief Scientist for Climate Change Programs with the Climate Institute in Washington DC. He received his B.S. in Engineering from Princeton University in 1964 and Ph.D. in Applied Science from the University of California Davis/Livermore in 1968. From 1968-1993, Mike conducted research on climate change and air pollution with the University of California’s Lawrence Livermore National Laboratory (LLNL). He also served as deputy division leader (1974-1987) and division leader (1987-1993) for LLNL’s Atmospheric and Geophysical Sciences Division. From 1993-2002, Mike was detailed as senior global change scientist to the interagency Office of the U.S. Global Change Research Program (USGCRP), serving as the first executive director of the Office from 1993-1997 and then as executive director of the USGCRP’s National Assessment Coordination Office from 1997-2001. During this assignment from LLNL, Mike also helped coordinate the US Government review of the Second and Third Assessment Reports of the Intergovernmental Panel on Climate Change (IPCC). Since retiring in 2002, Mike has served on the synthesis team for the Arctic Climate Impact Assessment (2002-2004), review editor for the North America chapter of the Fourth Assessment Report of IPCC (2005-2007), president (2003-2007) of the International Association of Meteorology and Atmospheric Sciences (IAMAS), and as a coordinating lead author on the 2007 report Confronting Climate Change: Avoiding the Unmanageable and Managing the Unavoidable prepared at the request of the UN Commission on Sustainable Development.