Two of the nation's premier atmospheric scientists, after reviewing extensive research by their colleagues, say there is no longer any doubt that human activities are having measurable--and increasing--impacts on global climate. Their study cites atmospheric observations and multiple computer models to paint a detailed picture of climate changes likely to buffet Earth in coming decades, including rising temperatures and an increase in extreme weather events, such as flooding and drought. The study appeared December 5 in Science as part of the journal's "State of the Planet" series. The coauthors--Thomas Karl, director of NOAA's National Climatic Data Center, and Kevin Trenberth, head of the Climate Analysis Section at the National Center for Atmospheric Research (NCAR)--conclude that industrial emissions have been the dominant influence on climate change for the past 50 years, overwhelming natural forces. The most important of these emissions is carbon dioxide, a greenhouse gas that traps solar radiation and warms the planet. "There is no doubt that the composition of the atmosphere is changing because of human activities, and today greenhouse gases are the largest human influence on global climate," they write. "The likely result is more frequent heat waves, droughts, extreme precipitation events, and related impacts, e.g., wildfires, heat stress, vegetation changes, and sea-level rise which will be regionally dependent." [continued]
