Greenhouse gas levels currently expected by mid-century will produce devastating long-term droughts and a sea-level rise that will persist for 1,000 years regardless of how well the world curbs future emissions of carbon dioxide, an international team of scientists reported yesterday.

NASA could be one of the nation's most potent weapons in battling climate change. The space agency has conducted decades of research into weather, life-support systems and the atmospheres of other planets providing it with unique skills to address this problem.

New research indicates that freshwater from melting icebergs may have led to the collapse of the North Atlantic Current and caused previous periods of abrupt global warming.

Research on Arctic and North Atlantic ecosystems shows the recent warming trend counts as the most dramatic climate change since the onset of human civilization 5,000 years ago.

Global warming has become such an overriding emergency that some climate experts are willing to consider schemes for partly shielding the planet from the sun's rays. Critics warn that no such scheme is a magic bullet and emission reduction strategies will still have to go forward.

A growing number of ecologists worry that conservation-as-usual won't be able to keep up with the predicted pace of climate change. To some of them, assisted migration, or helping plant and animal species make the move to a more survivable climate,  is a more proactive tool for preserving nature's richness, and possibly the only hope for saving certain species.

In the debate over global warming, there has been a widespread assumption that if humans are changing the earth's climate, the effects will be felt gradually and smoothly, making it easier to adapt to the change. But a growing accumulation of geological evidence is making it ever clearer that in the past, the climate has undergone drastic changes in temperature and rainfall patterns in the space of a human lifetime, in a decade or in even less time.

Arctic scientists have discovered that massive deposits of sub-sea methane, a gas 20 times more damaging than carbon dioxide, are bubbling to the surface as the Arctic region becomes warmer and its ice retreats.

Six U.S. National Laboratories have launched a program to research abrupt climate change which could be caused by methane release from thawing permafrost, the collapse of ice sheets, or other positive feedback mechanisms.

If the 100 largest cities in the world replaced their dark roofs with white shingles and their asphalt-based roads with concrete or other light-colored material, it could offset 44 metric gigatons (billion tons) of greenhouse gases, a study by Lawrence Berkeley National Laboratory and UC Berkeley shows.