No Doubt Of Link Between Humans And Global Warming, Researchers Say

Co-authors 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 warms the planet.

Results of the study, which appears in the December 5th issue of the journal Science as part of a "State of the Planet" assessment, says atmospheric observations and multiple computer models paint a detailed picture. "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," their report says.

Karl and Trenberth estimate that before 2100, global temperatures will rise 3-9 degrees farenheit. The increase would have widespread impacts on society and the environment, including melting the great ice sheets of Greenland and Antarctica and inundating the world's coasts. The authors base their estimate on computer model experiments by a number of climate scientists, observations of atmospheric changes and recorded climate changes over the past century.

If current emissions continue, the world would face the fastest rate of climate change in at least the past 10,000 years. This could potentially alter ocean current circulations and radically change existing climate patterns. Moreover, certain natural processes would likely accelerate the warming. As snow cover melts away, for example, the darker land and water surface would absorb more solar radiation, further increasing temperatures.

"Climate change is truly a global issue, one that may prove to be humanity's greatest challenge," the authors conclude. "It is very unlikely to be adequately addressed without greatly improved international cooperation and action."