Sudden changes in the volume of meltwater contribute more to the acceleration - and eventual loss - of the Greenland ice sheet than the gradual increase of temperature, according to a University of British Columbia study.

The ice sheet consists of layers of compressed snow and covers roughly 80 per cent of the surface of Greenland. Since the 1990s, it has been documented to be losing approximately 100 billion tonnes of ice per year - a process that most scientists agree is accelerating, but has been poorly understood. Some of the loss has been attributed to accelerated glacier flow towards ocean outlets.

Now a new study, to be published tomorrow in the journal Nature, shows that a steady meltwater supply from gradual warming may in fact slow down glacier flow, while sudden water input could cause glaciers to speed up and spread, resulting in increased melt.

A scuba diver who came face-to-teeth with a shark used a camera to fend off the animal when it came at him with its teeth bared - and he has the frightening video to prove it.

Scott MacNichol, 30, was shaken up but uninjured after a porbeagle shark apparently mistook his camera equipment for food Saturday while diving near Eastport, off the eastern tip of Maine. He estimated the shark was 8 feet long (2.4 meters) and weighed about 300 pounds (136 kilograms).

MacNichol saw the shark swimming above him while he was filming the ocean floor under empty salmon pens as part of an environmental assessment for Cooke Aquaculture Inc. The animal then came at him, jabbing at the camera with its snout. In the video, its sharp teeth fill the frame before it swims off.

"He took a couple of bites at the camera. When he did that I was pretty much petrified," MacNichol said Wednesday. "If you watch the video, you can hear me screaming underwater."

A group of top NASA boffins says that current climate models predicting global warming are far too gloomy, and have failed to properly account for an important cooling factor which will come into play as CO2 levels rise.

According to Lahouari Bounoua of NASA's Goddard Space Flight Center, and other scientists from NASA and the US National Oceanic and Atmospheric Administration (NOAA), existing models fail to accurately include the effects of rising CO2 levels on green plants. As green plants breathe in CO2 in the process of photosynthesis - they also release oxygen, the only reason that there is any in the air for us to breathe - more carbon dioxide has important effects on them.

Shivering Britain can expect at least another month of bitterly cold temperatures with many parts failing to get much above zero until the middle of January, forecasters have warned.

So far December has seen some of the coldest temperatures and heaviest snowfalls since 1981, but with no let up on the horizon, it could end up being the worst winter since 1910.

Parts of northern England and central Scotland have seen lows of (0F) -18C while the mercury has continued to drop in the south.

But apart from a brief respite over the coming weekend, when temperatures are expected to climb slightly, the cold snap is likely to continue throughout Christmas and well into January.

The heaviest snowfall in almost 25 years left much of the Paris region paralysed, with drivers advised not to use their cars unless absolutely necessary.

Brice Hortefeux, the interior minister, asked drivers to leave their vehicles at home the day after more than four inches of snow fell on Paris, the most since 1987.

Thousands of passengers spent the night at Roissy Charles de Gaulle airport after their flights were cancelled, and thousands more stranded motorists were put up in municipal halls and school sports halls around the Paris region.

In Velizy, southwest of Paris, between 7,000 and 8,000 people spent the night in company offices, at a shopping centre and in a sports hall.

After weeks of unseasonably warm and sunny weather, a cold snap from the Balkans arrived in Turkey accompanied by rain, sleet and snow. The strong storms caused flooding in the Aegean province of Aydın that killed one person and left two others missing Friday.

Bad weather has affected life in Istanbul, with increasing accidents and heavy traffic snarling the city's motorways. Some airplane flights and ferries scheduled to operate Friday have been canceled as a consequence of the weather.

The Turkish State Meteorological Service, or DMİ, forecasts rainy weather for the western Marmara sea, Black sea, southern Aegean and Mediterranean regions of the country, while the eastern Marmara region, including Istanbul, Sakarya and Kocaeli provinces, the Aegean, Göller, Anatolian and western Black Sea regions are expected to receive snow.

Researchers argue for a type of vegetative group decision making usually associated with animals

They're underfoot and underappreciated. But the roots of a plant may demonstrate the remarkable wisdom of crowds just as swarms of honeybees or humans can.

Three plant scientists now propose that roots growing this way and that in their dark and dangerous soil world may fit a definition for what's called swarm intelligence. Each tip in a root system acquires information at least partly independently, says plant cell biologist František Baluška of the University of Bonn in Germany. If that information gets processed in interactions with other roots and the whole tangle then solves what might be considered a cognitive problem in a way that a lone root couldn't, he says, then that would be swarm intelligence.

The decisions that emerge from groups of individuals have intrigued a wide range of researchers, for in some cases crowds show an eerie wisdom. Honeybees looking for a new home can collectively pick excellent nest sites even as individual scouts advocate for a variety of choices. And combining people's estimates of how many marbles are in a jar or what an animal at a country fair would yield in pounds of butchered meat often come quite close to the correct answer.

Plant life may exhibit collective decision making too, Baluška and his colleagues propose in the December Trends in Ecology and Evolution. They urge researchers to look beyond the animal kingdom and into the behavior of plant roots for evidence of crowd wisdom. Information could pass among root tips via secreted chemicals, released gases or perhaps even electrical activity that connects "brainlike" command centers in root tips, the researchers propose. But however the information travels, the interactions could yield swarmlike decisions about where and how much to grow.

The irony: As negotiators from nearly 200 countries met in Cancun to strategize ways to keep the planet from getting hotter, the temperature in the seaside Mexican city plunged to a 100-year record low of 54° F. Climate-change skeptics are gleefully calling Cancun's weather the latest example of the "Gore Effect" - a plunge in temperature they say occurs wherever former Vice President Al Gore, now a Nobel Prize-winning environmental activist, makes a speech about the climate. Although Gore is not scheduled to speak in Cancun, "it could be that the Gore Effect has announced his secret arrival," jokes former NASA scientist Roy W. Spencer.

The reaction: ClimateGate was "bad enough," says Duncan Davidson in Wall Street Pit, but Cancun's weather is particularly "inconvenient" for global-warming alarmists. It's a reminder that global temperatures have "flatlined" despite rising carbon dioxide levels, "which is decidedly chilling against the concept of hampering economic growth to limit Co2 emissions." Grow up, says Tony Juniper in The Independent. "Sure, it's cold outside," but "the trend data show that the world is warming, that the climate is changing, and that the release of greenhouse gases is the cause."

Conway - The U.S. Geological Survey said 53 earthquakes have been recorded in northern Faulkner County in just one week.

The Log Cabin Democrat newspaper at Conway reported Thursday that the earthquakes, all of them small, were recorded as occurring in the vicinity of Guy in the northern part of the county from Dec. 3 through Wednesday, with 25 quakes recorded on Sunday.

The largest of the quakes had a magnitude of 2.6. Researchers say quakes of 2.5 to 3.0 magnitude are typically the smallest felt by humans.

There were no reports of injuries or structural damage.

A coalition of beekeepers and environmentalists is asking the Environmental Protection Agency to remove a pesticide from the market because it might kill honeybees.

The request is in response to the leak of an internal EPA document that questions the scientific underpinning of the 2003 approval of clothianidin, a Bayer CropScience product used extensively on corn, the coalition said.

The letter to EPA administrator Lisa Jackson was sent by honeybee associations and representatives of Beyond Pesticides of Washington, the Pesticide Action Network of North America of San Francisco and the Center for Biological Diversity of Tucson.