Big Freeze Plunged Europe Into Ice Age in Months

ScienceDaily (Nov. 30, 2009) — In the film The Day After Tomorrow, the world enters the icy grip of a new glacial period within the space of just a few weeks. Now new research shows that this scenario may not be so far from the truth after all.


William Patterson, from the University of Saskatchewan in Canada, and his colleagues have shown that switching off the North Atlantic circulation can force the Northern hemisphere into a mini 'ice age' in a matter of months. Previous work has indicated that this process would take tens of years.
Around 12,800 years ago the northern hemisphere was hit by a mini ice-age, known by scientists as the Younger Dryas, and nicknamed the 'Big Freeze', which lasted around 1300 years. Geological evidence shows that the Big Freeze was brought about by a sudden influx of freshwater, when the glacial Lake Agassiz in North America burst its banks and poured into the North Atlantic and Arctic Oceans. This vast pulse, a greater volume than all of North America's Great Lakes combined, diluted the North Atlantic conveyor belt and brought it to a halt.
Without the warming influence of this ocean circulation temperatures across the Northern hemisphere plummeted, ice sheets grew and human civilisation fell apart.
Previous evidence from Greenland ice cores has indicated that this sudden change in climate occurred over the space of a decade or so. Now new data shows that the change was amazingly abrupt, taking place over the course of a few months, or a year or two at most.

 New research shows that switching off the North Atlantic circulation can force the Northern hemisphere into a mini 'ice age' in a matter of months. Previous work has indicated that this process would take tens of years.

Patterson and his colleagues have created the highest resolution record of the 'Big Freeze' event to date, from a mud core taken from an ancient lake, Lough Monreach, in Ireland. Using a scalpel layers were sliced from the core, just 0.5mm thick, representing a time period of one to three months.
Carbon isotopes in each slice reveal how productive the lake was, while oxygen isotopes give a picture of temperature and rainfall. At the start of the 'Big Freeze' their new record shows that temperatures plummeted and lake productivity stopped over the course of just a few years. "It would be like taking Ireland today and moving it up to Svalbard, creating icy conditions in a very short period of time," says Patterson, who presented the findings at the European Science Foundation BOREAS conference on humans in the Arctic, in Rovaniemi, Finland.
Meanwhile, their isotope record from the end of the Big Freeze shows that it took around two centuries for the lake and climate to recover, rather than the abrupt decade or so that ice cores indicate. "This makes sense because it would take time for the ocean and atmospheric circulation to turn on again," says Patterson.
Looking ahead to the future Patterson says there is no reason why a 'Big Freeze' shouldn't happen again. "If the Greenland ice sheet melted suddenly it would be catastrophic," he says.
This study was part of a broad network of 38 individual research teams from Europe, Russia, Canada and the USA forming the European Science Foundation EUROCORES programme 'Histories from the North -- environments, movements, narratives' (BOREAS). This highly interdisciplinary initiative brought together scientists from a wide range of disciplines including humanities, social, medical, environmental and climate sciences.

Ozone Hole Healing Could Cause Further Climate Warming

ScienceDaily (Jan. 26, 2010) — The hole in the ozone layer is now steadily closing, but its repair could actually increase warming in the southern hemisphere, according to scientists at the University of Leeds.

The Antarctic ozone hole was once regarded as one of the biggest environmental threats, but the discovery of a previously undiscovered feedback shows that it has instead helped to shield this region from carbon-induced warming over the past two decades.
High-speed winds in the area beneath the hole have led to the formation of brighter summertime clouds, which reflect more of the sun's powerful rays.
"These clouds have acted like a mirror to the sun's rays, reflecting the sun's heat away from the surface to the extent that warming from rising carbon emissions has effectively been cancelled out in this region during the summertime," said Professor Ken Carslaw of the University of Leeds who co-authored the research.
"If, as seems likely, these winds die down, rising CO₂ emissions could then cause the warming of the southern hemisphere to accelerate, which would have an impact on future climate predictions," he added.
The key to this newly-discovered feedback is aerosol -- tiny reflective particles suspended within the air that are known by experts to have a huge impact on climate.
Greenhouses gases absorb infrared radiation from the Earth and release it back into the atmosphere as heat, causing the planet to warm up over time. Aerosol works against this by reflecting heat from the sun back into space, cooling the planet as it does so.

Beneath the Antarctic ozone hole, high-speed winds whip up large amounts of sea spray, which contains millions of tiny salt particles. This spray then forms droplets and eventually clouds, and the increased spray over the last two decades has made these clouds brighter and more reflective.
As the ozone layer recovers it is believed that this feedback mechanism could decline in effectiveness, or even be reversed, leading to accelerated warming in the southern hemisphere.
"Our research highlights the value of today's state-of- the-art models and long-term datasets that enable such unexpected and complex climate feedbacks to be detected and accounted for in our future predictions," added Professor Carslaw.
The Leeds team made their prediction using a state-of-the-art global model of aerosols and two decades of meteorological data. The research was funded by the Natural Environment Research Council's Surface Ocean-Lower Atmosphere Study (UK SOLAS) and the Academy of Finland Centre of Excellence Programme.


source: http://www.sciencedaily.com/

Arctic Circle Crossing

from: Haley Smith Kingsland, Stanford University

66° 33’ N, 179° 85’ W, June 18 — Friday night, the following pipe reverberated throughout the Healy: “Now attention all hands. The cutter Healy has crossed into the Arctic Circle — the cold, icy waters of King Neptune. Welcome home, Polar Bears. All Blue Noses beware! That is all.”

"Polar Bears" are those who have already crossed the Arctic Circle and gone through initiation. "Blue Noses," on the other hand, have some surprises waiting for them. Everyone’s wondering what the secret initiation will be, including Blue Nose chief scientist Kevin Arrigo.

Immediately after the announcement, a crowd of scientists and Coasties gathered at the bow as the Healy passed through a belt of sea ice and herds of walruses. For many, it was the first sighting of both — a truly surreal night to remember.

“This is what I’ve been waiting for!” said Cedric Fichot, a graduate student at the University of South Carolina. (Photo by Haley Smith Kingsland)

The walrus’ scientific name, Odobenus rosmarus, means “tooth-walking sea horse” in Latin. Walrus tusks are really extended upper canine teeth that lengthen with age— up to three feet during a walrus’ lifetime. Walruses live on the sea ice edge over shallow continental shelves, and use their tusks to hoist themselves onto the ice and bore holes in it. Males also employ their tusks to threaten rivals. Walrus’ whiskers, or vibrissae, help them nuzzle and forage for shellfish on the shallow sea floor. How will climate change affect these gargantuan creatures? As Arctic sea ice melts and retreats from shallow continental shelves, walruses lose their habitat to water that’s too deep for them to dive for less abundant food. So instead they “haul out” to rest on coastal lands, and over-congregation leads to stampedes and trampling of young calves as well as stiff competition for limited resources. (Photo by Haley Smith Kingsland)

United States Geological Survey scientists have been tracking walruses with satellite radio-tags in order to trace their movements in the changing sea ice habitat. You can follow animations of the walrus’ paths in both the Chukchi and Bering Seas at . (Photo by Haley Smith Kingsland)