Thanks to Claudette J. Konola for sending along this great article on Global Warming...

Global warming trend on course to submerge coasts, researchers say MARTIN MITTELSTAEDT From Friday's Globe and Mail If current temperature trends continue to the end of the century, the Earth's climate will be warm enough to cause a massive melting of Greenland's ice sheet and a partial collapse of the Antarctic ice sheet, resulting in a torrent of melt water that will raise global sea levels by up to six metres, according to a pair of new research papers. The increase in ocean levels would devastate low-lying coastal areas, put dozens of major cities under water, and become irreversible at some point later this century "unless something is done to dramatically reduce human emissions of greenhouse gas pollution," warns Jonathan Overpeck, a professor at the University of Arizona and one of the researchers.He said that if serious efforts to limit global warming are not taken soon, "we're committed to four to six metres of sea-level rise in the future."The research is some of the most alarming to date on the possible effects of global warming, and was based on computer models that recreated the climate during the last really warm period in the Earth's history before the present era. That earlier epoch was an interglacial heat wave beginning about 130,000 years ago that caused northern regions to be bathed in an unusually long, warm spell lasting nearly 12,000 years.At the time, temperatures in Arctic regions were probably about three to five degrees warmer than they are now, and reached the same levels they are projected to attain later this century because of emissions of carbon dioxide and other greenhouse gases from human activity.If what happened in the past is any kind of prologue to what might happen in the future, scientists believe there will be serious consequences."Although the focus of our work is polar, the implications are global," said Bette Otto-Bliesner of the National Center for Atmospheric Research in Boulder, Colo., and another one of the researchers."These ice sheets melted before and sea levels rose," she said.She said the warmth needed isn't that much above present conditions.The two papers outlining the research are being published in the current issue of the journal Science.The finding could have major significance in the debate about the effects of global warming because it suggests that current projections on the change in sea levels due to the melting of ice sheets may be far too conservative.The UN's Intergovernmental Panel on Climate Change, the main body of scientists assessing the threat from global warming, has projected that rising sea levels would likely be a modest inconvenience, with ocean levels up anywhere from about one-10th of a metre to just under a metre by 2100.The new research concluded "that the melting could be faster and hence more challenging for society."The current rate of sea-level rise in the world's oceans is about 2.6 mm a year, or about the thickness of two dimes. The researchers said that at some points during the previous interglacial period, levels likely rose by 20 mm a year or more, suggesting that total increases of around two metres in a century are possible.That earlier warming spell caused about half of Greenland's ice cap to melt, the boreal forest to march northward to the Arctic ocean coastline in most areas of the North, and the disappearance of ice sheets from almost all areas of the Canadian High Arctic islands.Greenland even started to live up to the literal meaning of its name, at least in the southern part of the huge island, which at the time was covered in tundra similar to what is now found in much of Northern Canada.The melting in the Arctic region caused only about half of the rise in sea levels calculated to have occurred at the time, and the researchers concluded that some unknown process linked to the warming in the Northern Hemisphere then prompted a massive chuck of Antarctica's ice sheet to float into the ocean, accounting for the rest of the sea-level change.It is the first time studies have indicated that melting in the Arctic can trigger similar problems in the Antarctic, which has worrisome implications as the world's climate changes due to global warming.Investigations of the last interglacial period are a fascinating research topic for scientists trying to figure out what might happen in the near future because of global warming."It's the most recent time, even though it's a long time ago, where the temperatures in the Arctic were similar to what is forecast this century," said Shawn Marshall, a professor at the University of Calgary's geography department and the sole Canadian on the team that conducted the research. That last warm spell was unlike the one now under way, which is due to human causes, such as burning fossil fuels and clearing forests.According to Prof. Marshall, about 130,000 years ago, the Earth's orbit and tilt changed slightly, causing more intense sunlight to fall on Arctic regions. This extra warmth caused temperatures to remain above freezing for longer each summer in the North, triggering the vast melting that kept oceans at elevated levels for about 12,000 years.The orbit and tilt then changed, ending the warm period.To verify their findings on sea-level rise and the increase in temperature, the researchers looked for natural evidence to show they were on the right track.Prof. Marshall said one piece of strong corroborating evidence is that cores taken from the main ice fields now existing on islands in the Canadian High Arctic show nothing dating from before the last interglacial period, indicating it all must have melted.Older ice exists in Greenland, however, meaning that not all of its ice sheet melted.Researchers have also found plant pollen and seashells from things living in northern latitudes during the last interglacial period that could have survived only if temperatures were substantially warmer than those currently prevailing.