Subscribe to our free daily newsletters
. Earth Science News .




Subscribe to our free daily newsletters



WATER WORLD
Atlantic Ocean's slowdown tied to changes in the Southern Hemisphere
by Staff Writers
Seattle WA (SPX) Oct 10, 2016


This is a depiction of the global ocean circulation. In the Atlantic Ocean, warm water travels north at the surface, while cooler water travels south at depth. Researchers are studying what controls the strength of this circulation. Image courtesy NASA. For a larger version of this image please go here.

The ocean circulation that is responsible for England's mild climate appears to be slowing down. The shift is not sudden or dramatic, as in the 2004 sci-fi movie "The Day After Tomorrow," but it is a real effect that has consequences for the climates of eastern North America and Western Europe.

Also unlike in that movie, and in theories of long-term climate change, these recent trends are not connected with the melting of the Arctic sea ice and buildup of freshwater near the North Pole. Instead, they seem to be connected to shifts at the southern end of the planet, according to a recent University of Washington study in the journal Geophysical Research Letters.

"It doesn't work like in the movie, of course," said Kathryn Kelly, an oceanographer at the UW's Applied Physics Laboratory. "The slowdown is actually happening very gradually, but it seems to be happening like predicted: It does seem to be spinning down."

The study looked at data from satellites and ocean sensors off Miami that have tracked what's known as the Atlantic overturning circulation for more than a decade. Together they show a definite slowdown since 2004, confirming a trend suspected before then from spottier data.

Looking at other observations to determine the cause, the researchers ruled out what had been the prime suspect until now: that massive melting and freshening in the North Atlantic could stop water from sinking and put the brakes on the overturning circulation, which moves warmer water north along the ocean's surface and sends cold water southward at depths.

"It appears that this 10-year slowdown is not related to salinity," Kelly said. In fact, despite more ice melt, surface water in the Arctic is getting saltier and therefore denser, she said, because of less precipitation. "That means the slowdown could not possibly be due to salinity - it's just backwards. The North Atlantic has actually been getting saltier."

Instead, the authors saw a surprising connection with a current around the southern tip of South Africa. In what's known as the Agulhas Current, warm Indian Ocean water flows south along the African coast and around the continent's tip toward the Atlantic, but then makes a sharp turn back to join the stormy southern circumpolar current. Warm water that escapes into the Atlantic around the cape of South Africa is known as the Agulhas Leakage. The new research shows the amount of leakage changes with the quantity of heat transported northward by the overturning circulation.

"We've found that the two are connected, but I don't think we've found that one causes the other," Kelly said. "It's more likely that whatever changed the Agulhas changed the whole system."

She believes atmospheric changes may be affecting both currents simultaneously.

"Most people have thought this current should be driven by a salinity change, but maybe it's the [Southern Ocean] winds," Kelly said.

The finding could have implications for northern European and eastern U.S. climates, and for understanding how the world's oceans carry heat from the tropics toward the poles.

"I think it changes how we think about the whole Atlantic overturning circulation, of which the Gulf Stream is a part," said co-author LuAnne Thompson, a UW professor of oceanography. "It brings back the role of the atmosphere into what's controlling the climate in the high latitudes, that it's not all driven by what's happening in the oceans."

And while a slowdown of the Gulf Stream and broader overturning circulation, for whatever reason, would bring less warm water to eastern North America and Western Europe, any effects are overwhelmed by the overall warming due to global climate change.

"So that whole concept in the movie of New York harbor freezing doesn't make any sense," Kelly said. "If the Gulf Stream doesn't carry as much heat from the tropics, it just means that the North Atlantic is not going to warm up as fast as the rest of the ocean - it's not going to cool down."

The study was funded by NASA and the U.K.'s Natural Environment Research Council. Other co-authors are Kyla Drushka at the UW Applied Physics Laboratory, Dewi Le Bars at the Royal Netherlands Meteorological Institute and Elaine McDonagh at the U.K.'s University of Southampton.


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only

.


Related Links
University of Washington
Water News - Science, Technology and Politics






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

Previous Report
WATER WORLD
Clever fish keep cool
Port Aransas TX (SPX) Oct 06, 2016
Ocean warming is occurring at such a rapid rate that fish are searching for cooler waters to call home. A group of international scientists has new evidence that coral reef fish - which struggle to adapt to the warmer ocean temperatures brought about by global climate change - may instead opt to relocate to cooler parts of the ocean. In experiments using a common coral reef fish, the blue- ... read more


WATER WORLD
Haiti in pain as hurricane toll soars, aid sought

Agencies warn of fresh disaster as winter looms in flood-hit N. Korea

Haiti's hurricane survivors plead for aid

Haiti devastation slows aid effort

WATER WORLD
Study eyes radiation of everyday objects

French-Japanese laboratory to study materials under extreme conditions

Solving a cryptic puzzle with a little help from a hologram

Large volumes of data from ITER transferred to Japan at unprecedented speeds

WATER WORLD
Atlantic Ocean's slowdown tied to changes in the Southern Hemisphere

Vietnam court rejects fishermen lawsuits against Taiwan's Formosa

Ocean conditions contributed to unprecedented 2015 toxic algal bloom

Reservoirs are a major source of greenhouse gases

WATER WORLD
Ice cores reveal slow decline in oxygen over past 800K years

All polar bears across the Arctic face shorter sea ice season

Northern Lights trump street lights in Iceland

Global cooling yielded modern ecosystems 7 million years ago

WATER WORLD
As arable land disappears, here come the vertical farmers

Australian-Chinese bid for massive cattle estate

Madagascar hillsides stripped bare as locals seek land

Flower attracts pollinating flies by mimicking smell of attacked bee

WATER WORLD
Magma movements foretell future eruptions

Exhaling Earth: Scientists closer to forecasting volcanic eruptions

New fault discovered in earthquake-prone Southern California region

Japan's Mount Aso volcano erupts

WATER WORLD
Madagascar protests halt activity at Chinese gold mine

22 soldiers killed in attack on Niger refugee camp

Zimbabwe, Namibia to push for ivory trade

Ivory trade vote exposes divisions on saving elephant

WATER WORLD
Mapping the 'dark matter' of human DNA

Reading literary fiction doesn't boost social cognition

Why Does Dying Cost More for People of Color

World's first baby born from 3-parent technique: report




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News






The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement