Research published in a top scientific journal says Arctic sea ice has declined more in the last half-century than it has any time over the last 1,450 years.

The study, which gives the most detailed picture ever of the northern oceans over the previous millennium-and-a-half, also concludes the current decline has already lasted longer than any previous one in that period.

"When we look at our reconstruction, we can see that the decline that has occurred in the last 50 years or so seems to be unprecedented for the last 1,450 years," Christian Zdanowicz of the Geological Survey of Canada said Wednesday.

"It's difficult not to come up with the conclusion that greenhouse gases must have something to do with this," added Mr. Zdanowicz, one of the co-authors of the report in Nature.

A mid-November cold snap seems to have caught even seasoned Fairbanksans off guard.

"I don't think anybody was really expecting this," 43-year-old Shawn Ross, a lifelong Fairbanksan, said. "This came out of the blue."

For the second time in three days, Fairbanks set a new low temperature record on Thursday. A temperature of 41 degrees below zero - the first 40 below temperature of the season - was recorded at Fairbanks International Airport at 6:29 a.m., according to the National Weather Service in Fairbanks. That broke the old record of 39 below set in 1969.

The cold air settling in the flatlands has concentrated air pollution. The Fairbanks North Star Borough issued air quality advisories on Wednesday and Thursday because particulate matter was above the U.S. Environmental Protection Agency's standards and rated as unhealthy for sensitive groups.

Fairbanks set a new record of 35 below on Tuesday and the temperature bottomed out at 39 below on Wednesday, two degrees shy of the record.

Thursday's record low of 41 below marked the sixth earliest 40-below temperature recorded by the National Weather Service in Fairbanks since 1904. The earliest it's ever hit 40 below in Fairbanks was Nov. 5, 1907, when it hit 41 below.

Complex computational modeling provides clues to Neanderthal extinction

Computational modeling that examines evidence of how hominin groups evolved culturally and biologically in response to climate change during the last Ice Age also bears new insights into the extinction of Neanderthals. Details of the complex modeling experiments conducted at Arizona State University and the University of Colorado Denver will be published in the December issue of the journal Human Ecology, available online Nov. 17.

"To better understand human ecology, and especially how human culture and biology co-evolved among hunter-gatherers in the Late Pleistocene of Western Eurasia (ca. 128,000-11,500 years ago) we designed theoretical and methodological frameworks that incorporated feedback across three evolutionary systems: biological, cultural and environmental," said Michael Barton, a pioneer in the area of archaeological applications of computational modeling at Arizona State University.

Britain faces a sudden shivering end to the exceptionally warm late autumn with temperatures plunging towards Siberian levels.

Winter weather will arrive with a vengeance with temperatures well below zero within the next fortnight.

Experts then predict a bitterly cold December with thermometers falling at least as low as -15C (5F).

Snow could hit the country even earlier than last year when a big freeze at the end of November sent temperatures to -20C (-4F), crippling transport. And some forecasters fear that temperatures could plunge as low or even lower this winter.

New York has today been hit by snowfall before Halloween for only the fourth time since the Civil War.

The North East is bracing for a chilling weekend as 60 million people are expected to experience a rare October snowstorm, which will unleash heavy, wet snow and wind.

New England has already been struck by a very early snowfall and 10,000 residents in Pennsylvania, Maryland and West Virginia were today without power after snow, according to AccuWeather.com.

This weekend looks set to see huge amounts of sleet and snow covering the North East, invariably causing power outages and travel chaos. Some areas bracing for up to a foot of snow.

Hidden in the dark caves of southwest China, a fragment of Earth's last Ice Age might well survive. Sadly, there aren't any mammoths hiding out in there, but tiny plants might represent a last link to 30,000 years ago.

Researchers from the Chinese Academy of Science and the UK's Natural History Museum have identified seven species of nettle from the Guangxi and Yunnan provinces that are completely unlike the tropical vegetation that dominates the region. The nettles are only found in the darkest corners of the provinces' caves and gorges, places where barely any sunlight ever shines. In fact, some of the nettles have to survive on only 0.02% of total available sunlight - you don't find that level of darkness anywhere outside the ocean depths.

"Mars is not a dead planet -it undergoes climate changes that are even more pronounced than on Earth."

James Head, planetary geologist, Brown University

The prevailing thinking is that Mars is a planet whose active climate has been confined to the distant past. About 3.5 billion years ago, the Red Planet had extensive flowing water and then fell quiet - deadly quiet. It didn't seem the climate had changed much since. However, studies by scientists at Brown University have shown that Mars' climate has been much more dynamic than previously believed.

This high-resolution image above, taken by the Mars Reconnaissance Orbiter, shows the rock debris that Brown scientists believe was left by a glacier that rose at least one kilometer from the surrounding plain and flowed downward onto the canyon.

After examining this stunning high-resolution images taken by the Reconnaissance Orbiter, researchers documented for the first time that ice packs at least 1 kilometer (0.6 miles) thick and perhaps 2.5 kilometers (1.6 miles) thick existed along Mars' mid-latitude belt as recently as 100 million years ago. In addition, the team believes other images tell them that glaciers flowed in localized areas in the last 10 to 100 million years - a blink of the eye in Mars's geological timeline.

This evidence of recent activity means the Martian climate may change again and could bolster speculation about whether the Red Planet can, or did, support life.

"We've gone from seeing as a dead planet for three-plus billion years to one that has been alive in recent times," said Jay Dickson, a research analyst in the Department of Geological Sciences at Brown and lead author. "[The finding] has changed our perspective from a planet that has been dry and dead to one that is icy and active."

Pockmarked with wars, inflation, famines and shrinking humans, the 1600s in Europe came to be called the General Crisis.

But whereas historians have blamed those tumultuous decades on growing pains between feudalism and capitalism, a new study points to another culprit: the coldest stretch of the climate change period known as the Little Ice Age.

The Little Ice Age curbed agricultural production and eventually led to the European crisis, according to the authors of the study - said to be the first to scientifically verify cause-and-effect between climate change and large-scale human crises.

Prior to the industrial revolution, all European countries were by and large agrarian, and as study co-author David Zhang pointed out, "In agricultural societies, the economy is controlled by climate," since it dictates growing conditions.

A team led by Zhang, of the University of Hong Kong, pored over data from Europe and other the Northern Hemisphere regions between A.D. 1500 to 1800.

The team compared climate data, such as temperatures, with other variables, including population sizes, growth rates, wars and other social disturbances, agricultural production figures and famines, grain prices, and wages.

Field test by British academics marks first step towards recreating an artificial volcano that would inject particles into the stratosphere and cool the planet

It sounds barmy, audacious or sci-fi: a tethered balloon the size of Wembley stadium suspended 20km above Earth, linked to the ground by a giant garden hose pumping hundreds of tonnes of minute chemical particles a day into the thin stratospheric air to reflect sunlight and cool the planet.

But a team of British academics will next month formally announce the first step towards creating an artificial volcano by going ahead with the world's first major "geo-engineering" field-test in the next few months. The ultimate aim is to mimic the cooling effect that volcanoes have when they inject particles into the stratosphere that bounce some of the Sun's energy back into space, so preventing it from warming the Earth and mitigating the effects of man-made climate change.

Before the full-sized system can be deployed, the research team will test a scaled-down version of the balloon-and-hose design. Backed by a £1.6m government grant and the Royal Society, the team will send a balloon to a height of 1km over an undisclosed location. It will pump nothing more than water into the air, but it will allow climate scientists and engineers to gauge the engineering feasibility of the plan. Ultimately, they aim to test the impact of sulphates and other aerosol particles if they are sprayed directly into the stratosphere.

A polar blast has hit New Zealand, bringing freezing temperatures and the heaviest snowfall in 40 years.

Snow is even predicted to fall on the hills around Auckland in what meteorologists are describing as a once-in-a-lifetime storm.

Schools across the country have been closed for the day and most airports are at a standstill.

The bitterly cold southerly blast has now brought snow to most of New Zealand, closing roads and some airports and cutting power to thousands of homes.

Snow has made roads impassable in many areas of both islands.

MetService head forecaster Peter Kreft told the New Zealand Herald the polar blast was "of the order of a 50-year'' event and warned it could last for several more days.

"It's a once-in-many-decades event. We are probably looking at something like, in terms of extent and severity, maybe 50 years,'' he said.