Arctic Impact Crater Lake Reveals Interglacial Cycles in Sediments





The coring equipment and other instrumentation was set up using a tripod over the hole in the ice. The scientists were able to extract a core of the topmost 8.5 meters of sediment.
The coring equipment and other instrumentation was set up using a tripod over the hole in the ice. The scientists were able to extract a core of the topmost 8.5 meters of sediment.

A University of Arkansas researcher and a team of international scientists have taken cores from the sediments of a Canadian Arctic lake and found an interglacial record indicating two ice-free periods that could pre-date the Holocene Epoch.



Sonja Hausmann, assistant professor of geosciences in the J. William Fulbright College of Arts and Sciences at the University of Arkansas, and her colleagues will report their preliminary findings at the American Geophysical Union meeting this week.



The researchers traveled by increasingly smaller planes, Ski-doos and finally sleds dragged on foot to arrive at the Pingualuit Crater, located in the Parc National des Pingualuit in northern Quebec. The crater formed about 1.4 million years ago as the result of a meteorite impact, and today it hosts a lake about 267 meters deep. Its unique setting – the lake has no surface connection to other surrounding water bodies – makes it a prime candidate for the study of lake sediments.



Scientists study lake sediments to determine environmental information beyond historical records. Hausmann studies diatoms, unicellular algae with shells of silica, which remain in the sediments. Diatoms make excellent bioindicators, Hausmann said, because the diatom community composition changes with environmental changes in acidity, climate, nutrient availability and lake circulation.



By examining relationships between modern diatom communities and their environment, Hausmann and her colleagues can reconstruct various historic environmental changes quantitatively.



However, most sediments of lakes in previously glaciated areas have limitations – they only date back to the last ice age.


“Glaciers are powerful. They polish everything,” Hausmann said. Glaciers typically carve out any sediments in a lake bed, meaning any record before the ice age is swept away.



However, the unique composition of the Pingualuit Crater Lake led Michel A. Bouchard to speculate in 1989 that the sediments beneath its icy exterior might have escaped glacial sculpting. So in May of this year, Hausmann and her colleagues donned parkas, hauled equipment on ski-doos and slogged through sub-zero temperatures for three weeks so they could core sediments and collect data from the lake.



They carefully carved squares of ice out to make a small hole for equipment, then began a series of investigations that included pulling up a core of the topmost 8.5 meters of sediment. An echosounder indicated that the lake bottom may have more than 100 meters of relatively fine-grained sediments altogether. During the time since the expedition, researchers have examined the physical, magnetic and sedimentological properties of the sediment core.



The sediment core contains mostly faintly laminated silts or sandy mud with frequent pebble-size rock fragments, which is typical of deposits found in water bodies covered by an ice sheet. Sandwiched in the middle of the faintly laminated silts and sandy mud, the researchers found two distinct and separate layers containing organically rich material that most likely date back well before the Holocene, representing earlier ice-free periods. The samples they found contain the remains of diatoms and other organic material, suggesting that they represent ice-free conditions and possibly interglacial periods.



“There are no paleolimnological studies of lakes that cover several warm periods in this area,” Hausmann said. The terrestrial record will be complementary to marine records or to long ice-core records from Greenland.



The international team of researchers in the field included Guillaume St-Onge; Reinhard Pienitz, principal investigator; Veli-Pekka Salonen of the University of Helsinki, Finland; and Richard Niederreiter, coring expert. Please visit http://www.cen.ulaval.ca/pingualuit/index.html for more information.

Aurora Borealis breaks new grounds – and old ice


It can crush ice sideways and stay precisely on station to an accuracy of a metre. It can drill a hole 1,000 metres deep into the seabed while floating above 5,000 metres of ocean and it can generate 55 megawatts of power. So far, Aurora Borealis is the most unusual ship that has never been built, and it represents a floating laboratory for European science, a breakthrough for polar research and a very big headache for international lawyers.



Aurora Borealis will be the first ever international ship, the brainchild of the European Science Federation, the Alfred Wegener Institute for Polar and Maritime Research in Germany and the Germany Federal Ministry of Research and Education. Russia has announced that it will be a partner in launching this state-of-the-art research vessel, but other European nations may soon join the project. But a European ship represents a metaphorical voyage into unknown waters, the ESF Science Policy Conference learned.



“We do not have a European flag at the moment so one nation has to be responsible. And if it is internationally owned, you can imagine the difficulty,” said Nicole Biebow, manager of the project, and a scientist at the Alfred Wegener Institute. “We have to agree where this ship should have its home port. And what happens if there is an accident? Who is responsible if you have an oil spill on the ice, for instance?”


The ice over the polar seas masks millions of years of the planet’s history: drilling is difficult in freezing conditions. Aurora Borealis will be the world’s first icebreaker that is also a drilling ship. This sets unusual challenges for marine engineers: a vessel poised on top of 5000 metres of drilling rig cannot afford to move very much in any direction. But ice drifts, and currents and winds can alter in moments. So the ship will be designed not just to break the ice as it moves forward and astern, but also to port and starboard.



“We had some early ice tanks tests and they came up with a design that is able to break ice sideways,” said Paul Egerton, head of the European Polar Board within the European Science Federation. “As the ice continually presses against the side of the ship, the pieces of ice go underneath the hull and are washed away by the propulsion system. There is also a kind of damping system so the ship can raise itself up and down vertically to break the ice. It has a propeller that can turn 360 degrees, linked to satellite navigation. A lot of the cruise ships now have this so they can navigate in a very small area. But the propeller also has to break ice: it has to be strengthened.”



Not only will the diesel-electric ship be the floating equivalent of a 55 megawatt power station, it will be an intellectual powerhouse as well. It will be probe the role of polar waters in global climate change. Drill cores from the sea floor could answer questions about the geological history of the Arctic ocean, and other instruments will measure the transport of contaminants through the air, water and ice. The vessel could be home to 120 people, more than half of them scientists who need to go to sea to study the ice, the ocean beneath and the history of the deep sea floor.



It will be equipped with two “moon pools” in the bottom of the hull to give direct access to the open water beneath the ice, so that drillers can work in freezing conditions and biologists can launch underwater vehicles to study the mysterious processes that trigger an explosion of life in the polar seas every spring. The design and preparation of Aurora Borealis will continue until 2011. Builders could start assembling the hull in 2012, it could be cruising the oceans from 2014 – and it could begin answering some of the great questions of ocean science for the next 40 years.

New satellite study shows dramatic melting of Greenland ice during summer of 2007


Newly published research that includes satellite data from three separate sources shows that the seasonal melt on Greenland’s ice sheet during the summer of 2007 was a stunning 60 percent more than the previous high, set in 1998.



The new information, which differs from other studies by including information beginning in the early 1970s, is consistent with other indicators of worldwide global climate change, according to the author of the study, Thomas L. Mote, a climatologist from the University of Georgia.



“What we found was really quite remarkable,” said Mote, a professor in UGA’s department of geography and its Climatology Research Lab. “This work includes the longest satellite record anyone has for Greenland. No one piece of evidence ever tells the whole story, but when you put them together, they point in the same direction.”



Mote’s research was just published in the journal Geophysical Research Letters.



Perhaps just as dramatic as the huge increase in snow melt is that Greenland had as many as 50 more days of melt than average, and the melting season began a full month earlier than normal.



Mote has studied snow melt in Greenland for more than a decade, but even he was unprepared for the dramatic melt that occurred last summer. He compared data from three satellite sources:



  • The Special Sensor Microwave/Imager (SSM/I), which provided information from 1987 to present;



  • The Scanning Multichannel Microwave Radiometer (SMMR), which supplied data from 1979 to 1987; and



  • The Electrically Scanning Microwave Radiometer (ESMR), for data recorded in 1973, 1974 and 1976 respectively.




While other researchers had used data from SSM/I and SMMR, none had reexamined the older information generated from the ESMR satellite, and that longer record allowed Mote to see farther into the recent past of Greenland’s ice-sheet history.



“To be honest, there’s just not much useful satellite data prior to the 1980s,” said Mote.



There have been other warm periods in Greenland’s recent past, Mote says, most notably in the 1930s, though it’s difficult to say how much melt may have occurred then. But a dramatic change is now underway in a land that covers more than 800,000 square miles but has a permanent population of less than 60,000.



Just why the huge increase in melt occurred in the summer of 2007 is not yet entirely clear, said Mote. Certainly, increasing surface temperatures are part of it. Coastal meteorological stations showed higher-than-average temperatures for most of the season. But another culprit may be changes in the surface of the ice sheet itself.



Data show that the average number of melt days has been steadily increasing since 1997, and this may have allowed the ice sheet to become more susceptible to further melting. Large streams of water actually flow through chasms and cracks down to the land’s surface and cause the ice sheet to become unstable.



Another possible mechanism may be an increase in temperature of the snow or less snow accumulation in recent years, said Mote.



He points out that the noticeable summer melt of ice in Greenland is consistent with satellite observations that have pointed to decreasing sea ice across the Northern Hemisphere since 2000.



“The most recent Intergovernmental Panel on Climate Change assessment report concludes that changes in surface melting have contributed to a loss of mass in Greenland,” said Mote, “which they report is ‘very likely’ a contributor to global sea rise level.”



Researchers will be watching Greenland’s ice sheet warily next summer to see if the trend continues.

Arctic heat wave stuns climate change researchers





Undergraduate Geography student Joshua See, a member of Queen's International Polar Year project surveys the shifting terrain on Melville Island caused by this summer's record high temperatures in the Arctic. Photo Courtesy: Scott Lamoureux
Undergraduate Geography student Joshua See, a member of Queen’s International Polar Year project surveys the shifting terrain on Melville Island caused by this summer’s record high temperatures in the Arctic. Photo Courtesy: Scott Lamoureux

Unprecedented warm temperatures in the High Arctic this past summer were so extreme that researchers with a Queen’s University-led climate change project have begun revising their forecasts.



“Everything has changed dramatically in the watershed we observed,” reports Geography professor Scott Lamoureux, the leader of an International Polar Year project announced yesterday in Nunavut by Indian and Northern Affairs Minister Chuck Strahl. “It’s something we’d envisioned for the future – but to see it happening now is quite remarkable.”



One of 44 Canadian research initiatives to receive a total of $100 million (IPY) research funding from the federal government, Dr. Lamoureux’s new four-year project on remote Melville Island in the northwest Arctic brings together scientists and educators from three Canadian universities and the territory of Nunavut. They are studying how the amount of water will vary as climate changes, and how that affects the water quality and ecosystem sustainability of plants and animals that depend on it.



The information will be key to improving models for predicting future climate change in the High Arctic, which is critical to the everyday living conditions of people living there, especially through the lakes and rivers where they obtain their drinking water.



Other members of the research team include, from the Queen’s Geography Department: Paul Treitz, Melissa Lafreniere and Neal Scott; Myrna Simpson and Andre Simpson from U of T; and Pierre Francus from INRS-ETE, Quebec. Linda Lamoureux of Kingston’s Martello School will work with the scientists to develop learning tools for schools in the north.



From their camp on Melville Island last July, where they recorded air temperatures over 20ºC (in an area with July temperatures that average 5ºC), the team watched in amazement as water from melting permafrost a metre below ground lubricated the topsoil, causing it to slide down slopes, clearing everything in its path and thrusting up ridges at the valley bottom “that piled up like a rug,” says Dr. Lamoureux, an expert in hydro-climatic variability and landscape processes. “The landscape was being torn to pieces, literally before our eyes. A major river was dammed by a slide along a 200-metre length of the channel. River flow will be changed for years, if not decades to come.”


Comparing this summer’s observations against aerial photos dating back to the 1950s, and the team’s monitoring of the area for the past five years, the research leader calls the present conditions “unprecedented” in scope and activity. What’s most interesting, he says, is that their findings represent the impact of just one exceptional summer.



“A considerable amount of vegetation has been disturbed and we observed a sharp rise in erosion and a change in sediment load in the river,” Dr. Lamoureux notes. “With warmer conditions and greater thaw depth predicted, the cumulative effect of this happening year after year could create huge problems for both the aquatic and land populations. This kind of disturbance also has important consequences for existing and future infrastructure in the region, like roads, pipelines and air strips.”



If this were to occur in more inhabited parts of Canada, it would be “catastrophic” in terms of land use and resources, he continues. “It would be like taking an area the size of Kingston and having 15 per cent of it disappear into Lake Ontario.”



The Queen’s-led project is working with other IPY research groups including: Arctic HYDRA, an international group investigating the impact of climate change on water in the Arctic; Science Pub, a Norwegian group working on broad research from science to public education about the impacts of global warming; and CiCAT, a University of British Columbia-led group of 48 researchers investigating the impacts of climate change on tundra vegetation.



International Polar Year (IPY) is the largest-ever international program of coordinated scientific research focused on the Arctic and Antarctic regions and the first in 50 years.

Arctic Sea Ice Bottoms Out For 2007, Shatters All Time Record Low





The minimum low Arctic sea ice extent for 2007 is about 460,000 square miles less than the previous minimum record, set in 2005. The area of lost sea ice is roughly the equivalent of the area of Texas and California combined.
The minimum low Arctic sea ice extent for 2007 is about 460,000 square miles less than the previous minimum record, set in 2005. The area of lost sea ice is roughly the equivalent of the area of Texas and California combined.

Scientists from the University of Colorado at Boulder’s National Snow and Ice Data Center said today that the extent of Arctic sea ice appears to have reached its minimum for 2007 on Sept. 16, shattering all previous lows since satellite record-keeping began nearly 30 years ago.



The Arctic sea ice extent on Sept. 16 stood at 1.59 million square miles, or 4.13 million square kilometers, as calculated using a five-day running average, according to the team. Compared to the long-term minimum average from 1979 to 2000, the new minimum extent was lower by about 1 million square miles — an area about the size of Alaska and Texas combined, or 10 United Kingdoms, they reported.



The minimum also breaks the previous minimum set on Sept. 20 and Sept. 21 of 2005 by about 460,000 square miles, an area roughly the size of Texas and California combined, or five United Kingdoms, they found. The sea ice extent is the total area of all Arctic regions where ice covers at least 15 percent of the ocean surface.



Scientists blame the declining Arctic sea ice on rising concentrations of greenhouse gases that have elevated temperatures from 2 degrees F to 7 degrees F across the arctic and strong natural variability in Arctic sea ice, said the researchers.


The CU-Boulder research group said determining the annual minimum sea ice is difficult until the melt season has decisively ended. But the team has recorded five days of little change, and even slight gains in Arctic sea ice extent this September, so reaching a lower minimum for 2007 seems unlikely, they reported.



Arctic sea ice generally reaches its minimum extent in September and its maximum extent in March. The researchers used satellite data from NASA, the National Oceanic and Atmospheric Administration and the U.S. Department of Defense, as well as data from Canadian satellites and weather observatories for the study.



The CU-Boulder research group is reporting the news on its ongoing blog, along with images and discussion, which can be found on the Web at: nsidc.org/news/press/2007_seaiceminimum/20070810_index.html.



“The amount of ice loss this year absolutely stunned us because it didn’t just beat all previous records, it completely shattered them,” said CU-Boulder senior scientist Mark Serreze of NSIDC.