To better understand global warming -- and the role of largely man-made changes that began with the Industrial Age two centuries ago and are now galloping at breakneck speed -- scientists aboard the CCGS Amundsen hunt for clues in the mud and bedrock, peat moss and plankton and permafrost. Using sonars and CAT scans, radioactive isotopes like carbon 14 and other indelible markers, they seek to chart and date everything from where the seawater came from, and when, to how long sediment layers have rested undisturbed on the sea floor.

NACHVAK FJORD, Labrador -- Beneath their sheaths of ice and permafrost, those blustery islands at the top of the world hide souvenirs of a distant tropical past. Remnants of fossil forests are strewn across the ridges of Ellesmere and Axel Heiberg in Canada's High Arctic. In Norway's Svalbard archipelago, the rocky cliffs of Spitsbergen are embedded with coral shells, relics from centuries spent somewhere south of modern-day Fort Lauderdale.

Even the North Pole isn't where it used to be, with the magnetic pole whimsically drifting as much as 1,100 kilometres over the last millennium.

And here above the 61st parallel, peaks are twice as tall as Mont Tremblant, steeper and more extensive than anything east of the Rockies. Chiselled and crinkled with origami folds, they plunge deep to wide, bowl-shaped valleys carved by vanishing glaciers many thousands of years ago.

None of it makes sense, except perhaps to geomorphologists and oceanographers who spend their lives examining the distant past to predict the future. For them, climate change is as old as the hills here, and possibly older.

Scientists know that our planet has warmed and cooled with extraordinary haste and dramatic consequences, bending and twisting like Silly Putty both before and after the last ice age 10,000 years ago. The biggest difference this time is that humans are here to put a finger in the wind and record the damage.

To better understand global warming -- and the role of largely man-made changes that began with the Industrial Age two centuries ago and are now galloping at breakneck speed -- scientists aboard the CCGS Amundsen hunt for clues in the mud and bedrock, peat moss and plankton and permafrost. Using sonars and CAT scans, radioactive isotopes like carbon 14 and other indelible markers, they seek to chart and date everything from where the seawater came from, and when, to how long sediment layers have rested undisturbed on the sea floor.

Sam Bentley is a marine sedimentologist in the earth sciences department at Memorial University in St. John's, Nfld., where he holds the Canada Research Chair in Seabed Imaging -- the art of dating sea floor sediments and the records they contain of environmental practices dating back hundreds of years.

For Bentley, who obviously revels in the opportunity to put on his "Mud Cowboy" hard hat and bright orange fisherman's overalls, it's a licence to play in the dirt.

"I think it is important that we have a clear sense of context," says the Atlanta native whose research has taken him from the Mississippi delta (before and since Hurricane Katrina) to Papua New Guinea and the sediment-choked waterways of New Zealand.

"If we are trying to deal with and or predict the effects of climate change, then knowing what environmental conditions preceded the present status quo is important."

Not the least of this, Bentley said, is knowing how much of what is happening is the result of human behaviour -- such as spewing fossil fuels into the atmosphere or diverting huge waterways -- and how much is the result of the Earth's own dynamics. "Or is it a combination? It's something that we need to know."

On the Amundsen, Bentley and research assistants Peter Huelse and Rob Haworth have been using a tool called a box core to collect sediment samples from selected sites in three Labrador fjords and major river estuaries in Hudson Bay.

A nifty shovel and metal box contraption that is hooked to the ship's winch and lowered to the sea floor 120 metres below, the device allows scientists to haul up a tidy segment of sediment -- roughly a quarter of a square metre -- exactly as the layers sat below the water, perhaps for hundreds of years.

"The beauty of the tool is that it allows you to recover a pristine section of the sea floor with an undisturbed sediment surface and an undisturbed layer in about the upper 50-60 centimetres. And this is what we need to be able to reconstruct these detailed chronologies," said Bentley.

Mucky layers of mud, sand, silt and clay are still oozing sea urchins and anemones when Bentley's team slides sediment samples into two clear sheathes of heavy plastic, but not before he conducts an impromptu taste test. "If it tastes slightly grainy, it's silt. If there's a creamy taste, it's pure clay," he says, licking a dab of sludge from his fingertip.

Since more water usually means more sediment, a first analysis should give Bentley a rough idea of river flow patterns over time.

Back in the lab, he then uses radioactive markers, some of them natural, others the result of human activity, to pinpoint the vintage of the sediment layers. For instance, Bentley knows that sediment particles that contain radioactive isotopes released by hydrogen-bomb testing can only date back as far as the 1950s.

By examining the proportion and physical properties of sediment discharged from a river into the ocean over a specific period of time, scientists can infer how water flow has changed over the last 200 years, providing a window on human and natural impacts and the stability or instability of the climate in the Arctic and sub-Arctic.

For the ArcticNet expedition, Bentley's team is looking for signs of either increased or decreased discharge of water and sediment at the mouths of the Great Whale, Nelson and Churchill rivers, three large systems where dams and diversions have altered flow patterns and water volume over the last 40 years.

Recent studies suggest the amount of fresh water leaving Hudson Bay has dropped by 13 per cent since river gauges were installed in 1960. Yet scientists don't know what flow rates were before that.

"Is this a change, or is this the continuation of a previous existing trend?"

Understanding more about what those rivers have been doing for the last 150 or 200 years would, Bentley believes, provide us with a better sense of how much of what is happening there stems from carbon dioxide emissions and mammoth water projects on northern rivers.

So why should we care?

Roughly 40 per cent of the freshwater discharged from Canada empties into Hudson Bay, influencing ocean currents and the salt content of the eastern Canadian Arctic and Labrador Sea, which forms the northern boundary, and a kind of steering element, for the Gulf Stream.

Since the Gulf Stream is a major engine for warming the waters the North Atlantic, any shifts in the amount, temperature and saline content of incoming freshwater is worth noting, influencing the viability and travel patterns of marine species, weather systems and the ocean's long-term capacity to act as a filter.

A graduate student at the Institut des sciences de la mer in Rimouski, Michel Lajoie, also studies sediment cores to try to understand abrupt climate change -- in this case, the swift and monumental reversals that occurred some 8,000 years ago, right around the time a vast glacial pool known as Lake Agassiz flooded its banks, dumping 9,500 cubic metres of water into the ocean by way of Hudson Bay.

Many climate scientists have linked the draining of the huge lake, located in what is now the fertile Red River Valley, with a prolonged cold spell near the tail end of thelast ice age. Known as the Younger Dryas, the 1,200-year cold snap then ended in the blink of an eye, with average annual temperatures in northern latitudes climbing by as much as 10 degrees Celsius in just 10 years.

Lajoie and fellow paleo-oceanographers have been using long piston cores -- cylindrical samples anywhere from four to 12 metres in length -- to examine sediment from the Hudson Bay region dating back as much as 10,000 years, when the last ice age ended and the Holocene era began.

Aided by a CAT scan and monitors that allow him to account for constant shifts in the Earth's magnetic field, Lajoie grapples with ancient dilemmas that resonate today.

Did dynamic natural forces melt glaciers and cause Lake Agassiz to overflow?

Back then, a colossal surge of frigid water caused the ocean's warm water currents to shut down, sending northern latitudes back into the deep freeze.

Could it happen again?

"I study the past to have a better understanding of the future," said Lajoie.

It wasn't that long ago that scientists believed the transition from the ice age was relatively calm, but recent studies suggest it may have been abrupt and disruptive. "Now we have better data and we're seeing that the Holocene was like climate change."

One of the lessons of Lake Agassiz is that melting glaciers could mean a huge input of freshwater into oceans. "In Antarctica, there are lakes under the ice. If they were to flush into the ocean, what would happen?"

Huelse, a doctoral student from Munich, knows as well as anyone how fickle our planet can be. After all, climate change "has happened all the time since Earth's history started more than 4.5 billion years ago."

While studying for his master's, the 27-year-old spent two years at Spitsbergen, a fossil-hunter's treasure trove above the 75th parallel about 560 kilometres north of Norway.

On chalky cliffs some 300 million years old, researchers found sediment spanning five million years, each layer encrusted with micro-fossils revealing evidence of repeated changes in climate and environment.

"At this time, Spitsbergen was a shallow, warm, subtropical ocean with water depth between zero and 70 metres."

Yet as Huelse and his colleagues sliced the sediment, they found signs of cyclical shifts in the sea level.

Time and again, deep sea gave way to coral reefs and shallow lagoons, until the sea level dropped and a huge ice cap covered the region, then part of a super continent, which also included North America, Ellesmere Island and Greenland.

"This ice cap, due to climactical changes, sometimes melted partly down and then built up again, and this caused the sea level changes which we could record in this cliff."

When it comes to climate change, Bentley says he has "no idea whether we can roll back the clock and make sea ice conditions more like 150 years ago than they are now. But learning the causes for changes in the ice pack is something that's important. Because only by doing that can we ascertain what impact it could have."

Still, he confesses his training as a geologist sometimes prompts him to take the long view: "If Dr. Who were to go into outer space and come back in 150,000 years, the whole human occupation of Earth may be represented as a relatively thin layer of Coca-Cola bottles."

pcurranthegazette.canwest.com