Skip navigation

Gulf Stream's role in warming questioned

Arctic fresh water in current could actually help, researcher says

IMAGE: GULF STREAM SCIENTIST
Scientist Bogi Hansen retrieves sonar devices aboard his ship in Torshavn, Faeroe Islands, on May 22. For the past year, Hansen's sonar devices fitted to underwater buoys sent pings into the murky depths of the North Atlantic, measuring a crucial ocean current that has kept this subpolar archipelago unfrozen for centuries.
John McConnico / AP
INTERACTIVE
Carbon calculator
Wonder how much carbon dioxide you're responsible for on your commutes? Our map-based calculator will give you a pretty good idea, and get you started on a diet.
Slide shows
AP
Warming signals
View images from around the world that show signs of global warming.
To match feature CLIMATE-GREENLAND/WARMING
Reuters
Ice at the edge
View images of Greenland, where coastal edges of its vast ice cap are melting at an alarming rate.
Interactives
Vital Signs of a Warming World
The science, impacts and scenarios of climate shifts
Carbon trade game
Learn how "cap and trade" works and play along in a simulated market.
Rising seas
What future sea levels could mean for some of America's favorite places
The greenhouse effect
How the Earth maintains a temperature conducive to life
Cooling the planet
Check out five far-out ideas on how to engineer a cooler Earth.
Eyeing the ice
The National Science Foundation's Tom Wagner on why climate expert study Antarctica.
Melting mountains
Data shows five areas of concern
By Karl Ritter
updated 6:42 p.m. ET June 15, 2007

TORSHAVN, Faeroe Islands - From the deck of a research ship moored in these gusty north Atlantic islands, workers are offloading three bright orange buoys whose sonar devices will help Bogi Hansen fill more gaps in an intriguing twist on climate change forecasts.

For the past year, the Faeroese scientist’s sonar has been pinging the Gulf Stream, the warm ocean current that has kept this subpolar archipelago unfrozen for centuries. His findings are of big interest because they contradict one of the most catastrophic predictions linked to global warming: that Arctic melting will strangle the Gulf Stream, thrusting Europe into a new Ice Age.

In fact, Hansen’s research and recent climate models raise a tantalizing possibility: Can the slight weakening of the Gulf Stream expected over the next century actually help to offset the effects of global warming in northern Europe?

Story continues below ↓
advertisement | your ad here

Some scientists think so.

“We will benefit a little bit from this,” said Helge Drange, of the Nansen Environmental and Remote Sensing Center in Bergen, Norway, a researcher who builds climate models. “Instead of warming of 3-4 degrees C (5-7 F), we may get 2-3 degrees C (4-5 F) in northwestern Europe.”

The U.N.-sponsored Intergovernmental Panel on Climate Change said this year that the global ocean circulation powering the Gulf Stream is likely to slow, but is “very unlikely” to suffer an abrupt change.

No climate models project a complete shutdown of the Gulf Stream, which feeds warm water up the east coast of North America and across the Atlantic Ocean to Europe.

“It’s one of the good news things in the climate story,” said Andrew Weaver, a Canadian researcher and lead author of a chapter dealing with ocean currents in the IPCC report. “To be perfectly honest, it’s difficult to fathom a mechanism that could cause its collapse.”

Hansen said his latest measurements on the underwater Greenland-Scotland ridge show no weakening in the North Atlantic Drift, the crucial northward branch of the Gulf Stream.

Fresh vs. salt water
Scientists expect the flow to taper off in coming decades by up to 50 percent as Greenland’s melting ice sheet releases freshwater into the north Atlantic, slowing the main pump that drives what is known as the ocean conveyor belt — the global circulation of currents. It is high salinity that causes Arctic water to sink and generate the energy for the Gulf Stream.

Hansen said current projections show that this process “would mitigate the global warming” rather than cause an abrupt and cataclysmic cooling.

Still, there are plenty of uncertainties.

While northwestern Europe, from Britain to Scandinavia, can expect continued gradual warming, the net effect of climate change and a slower Gulf Stream is harder to predict for north Atlantic islands such as Iceland or the Faeroes, a semiautonomous Danish territory with 50,000 inhabitants.

Here, right in the middle of the North Atlantic Drift, is where the warming effect is most pronounced. The average winter temperature in Torshavn is 37 F — about 22 F higher than in Anchorage, Alaska, which is on the same latitude.

“The Faeroes would be very much colder but also large areas of this region and the whole Arctic would be very much affected if this flow of heat would weaken considerably,” Hansen said.

Even a slight cooling could mean the difference between green and white winters for places like the Faeroes where average winter temperatures are just above freezing.

A slowdown in the circulation could also affect marine life, because it transports oxygen and other substances to the deep ocean.


Sponsored LinksGet listed here
Online College Courses
Boost your career with an online Degree. Pick from Leading Colleges!
www.EarnMyDegree.com

Sponsored links

Resource guide