Melting glaciers diminished Gulf Stream, cooled Western Europe, during last Ice Age

November 19, 2001

At the end of the last Ice Age --11.5 to 13 thousand years ago -- the north Atlantic deep water circulation system that drives the Gulf Stream may have shut down because of melting glaciers that added freshwater into the north Atlantic Ocean over several hundred years, confirm researchers funded by the National Science Foundation (NSF)'s paleoclimate program.

"For the first time, we have shown that realistic additions of glacial meltwater into the north Atlantic would have shut down north Atlantic deep water production over a period of a few hundred years, if the initial ocean circulation was somewhat weaker than that of today," said David Rind, lead author of the study and a senior climate researcher at the NASA Goddard Institute for Space Studies. The study appears in the current issue of Journal of Geophysical Research - Atmospheres.

While the study finds that freshwater input could slow the Gulf Stream, it would not stop it entirely. That's because the stream is partially pushed by winds. As a result, the model shows the reduced Gulf Stream would transport only about half as much heat northward, thereby cooling western Europe.

"This discovery illustrates the importance of a systems approach to research-studying the interactions among land, ocean, and atmospheric processes-to understand the complex behavior of Earth's climate," said James Yoder, director of NSF's division of ocean sciences. "But we still have much to learn before we can explain the rapid climate changes that have apparently occurred over the past few thousand years, and what those changes can tell us about what may happen in the future."

The computer model simulations of ocean and atmosphere processes used in this study imply that a similar phenomenon has the potential to occur in the future due to freshwater additions from increased rain and snow caused by global climate change.

When Rind and his colleagues entered into their model realistic estimates of freshwater from melting glaciers, they found the north Atlantic circulation stopped completely after some 300 years. When the model was adjusted to make the circulation weaker than it is today, cessation of the Gulf Stream took only 150-200 years, matching current estimates based on paleo-climate records.

When the Gulf Stream moves warm surface water from the equator north through the Atlantic, the water cools, gets saltier due to evaporation and becomes very dense. By the time it approaches the coast of Newfoundland, or further northeast in the Norwegian Sea, it becomes dense enough to sink. This process is called overturning. The dense water then slowly travels through the deep water southward into the Southern Hemisphere, with the return flow to the north occurring at the surface.

But when freshwater gets mixed with the salty water in the north Atlantic, it makes the water less dense and slows the overturning process and the ocean circulation.
Note: For related graphic, see

National Science Foundation

Related Ice Age Articles from Brightsurf:

Ice discharge in the North Pacific set off series of climate events during last ice age
Repeated catastrophic ice discharges from western North America into the North Pacific contributed to, and perhaps triggered, hemispheric-scale changes in the Earth's climate during the last ice age.

Ice Age manatees may have called Texas home
Manatees don't live year-round in Texas, but these gentle sea cows are known to occasionally visit, swimming in for a 'summer vacation' and returning to warmer waters for the winter.

Sea ice triggered the Little Ice Age, finds a new study
A new study finds a trigger for the Little Ice Age that cooled Europe from the 1300s through mid-1800s, and supports surprising model results suggesting that under the right conditions sudden climate changes can occur spontaneously, without external forcing.

How cold was the ice age? Researchers now know
A University of Arizona-led team has nailed down the temperature of the last ice age -- the Last Glacial Maximum of 20,000 years ago - to about 46 degrees Fahrenheit.

What causes an ice age to end?
Research by an international team helps to resolve some of the mystery of why ice ages end by establishing when they end.

New study results consistent with dog domestication during ice age
Analysis of Paleolithic-era teeth from a 28,500-year-old fossil site in the Czech Republic provides supporting evidence for two groups of canids -- one dog-like and the other wolf-like - with differing diets, which is consistent with the early domestication of dogs.

Did an extraterrestrial impact trigger the extinction of ice-age animals?
Based on research at White Pond near Elgin, South Carolina, University of South Carolina archaeologist Christopher Moore and 16 colleagues present new evidence of a controversial theory that suggests an extraterrestrial body crashing to Earth almost 13,000 years ago caused the extinction of many large animals and a probable population decline in early humans.

Dust in ice cores leads to new knowledge on the advancement of the ice before the ice age
Working with the ice core ReCap, drilled close to the coast in East Greenland, postdoc Marius Simonsen wondered why the dust particles from the interglacial period -- the warmer period of time between the ice ages -- were several times bigger than the dust particles from the ice age.

Ice-sheet variability during the last ice age from the perspective of marine sediment
By using marine sediment cores from Northwestern Australia, a Japanese team led by National Institute of Polar Research (NIPR) and the University of Tokyo revealed that the global ice sheet during the last ice age had changed in shorter time scale than previously thought.

What triggered the 100,000-year Ice Age cycle?
A slowing of ocean circulation in the waters surrounding Antarctica drastically altered the strength and more than doubled the length of global ice ages following the mid-Pleistocene transition, a new study finds.

Read More: Ice Age News and Ice Age Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to