Major Study Rewrites the Driving Source of Atlantic Ocean Circulation – Discover Magazine

By Roni Dengler

Massive volumes of water circulate throughout the Atlantic Ocean and serve as the central drivers of Earth’s climate. Now researchers have discovered that the heart of this circulation is not where they suspected.

“The general understanding has been [that it’s] in the Labrador Sea, which sits between the Canadian coast and the west side of Greenland,” said Susan Lozier, a physical oceanographer at Duke University in Durham, North Carolina, who led the new research. “What we found instead was that … the bulk [of it] is taking place from the east side of Greenland all the way over to the Scottish shelf.”

The discovery will help improve global climate models.

Read full article: http://blogs.discovermagazine.com/d-brief/2019/02/01/amoc-ocean-current-driving-cause/#.XFm3Iy2ZNp_

Ocean mixing that drives climate found in surprise location – AP

By Seth Borenstein

WASHINGTON (AP) — One of the key drivers of the world’s climate is an area in the North Atlantic Ocean where warmer and colder water mix and swirl. When scientists went for their first close look at this critical underwater dynamo, they found they were looking in the wrong place.

By hundreds of miles.

The consequences are not quite yet understood, but eventually it could change forecasts of one of the worst-case global warming scenarios — still considered unlikely this century — in which the mixing stops and climate chaos ensues.

It’s called the Atlantic Meridional Overturning Circulation , and scientists describe it as a giant ocean conveyor belt that moves water from Greenland south to beyond the tip of Africa and into the Indian Ocean.

Warm, salty water near the surface moves north and mixes with cold, fresher water near Greenland. As that water cools and sinks it drives a slow circulation of the oceans that is critical to global climate, affecting the location of droughts and frequency of hurricanes. It also stores heat-trapping carbon dioxide deep in the ocean. The faster it moves, the more warm water gets sent into the depths to cool.

The area where warm water turns over in the North Atlantic is considered to be the engine of the conveyor belt. Scientists thought it was in the Labrador Sea west of Greenland.

But then a new international science team measured temperature, saltiness and the speed of ocean currents throughout the North Atlantic to try to better understand the conveyor belt. The preliminary results after hundreds of measurements in 21 months found that engine was several hundreds of miles east of where they figured, said study lead author Susan Lozier, an ocean sciences professor at Duke University. The study, published in Thursday’s journal Science, puts it east of Greenland, closer to Scotland.

Read full article: https://www.apnews.com/595bfe2060ef46d49d2417082e3cbd18

A surprising new picture of ocean circulation could have major consequences for climate science – Washington Post

It may be the biggest wild card in the climate system. Scientists have long feared that the so-called “overturning” circulation in the Atlantic Ocean could slow down or even halt due to climate change — a change that would have enormous planetary consequences.

But at the same time, researchers have a limited understanding of how the circulation actually works, since taking measurements of its vast and remote currents is exceedingly difficult. And now, a major new research endeavor aimed at doing just that has suggested a dramatic revision of our understanding of the circulation itself.

A new 21-month series of observations in the frigid waters off Greenland has led to the discovery that most of the overturning — in which water not only sinks but returns southward again in the ocean depths — occurs to the east, rather than to the west, of the enormous ice island. If that’s correct, then climate models that suggest the circulation will slow as the climate warms may have to be revised to take this into account.

The magnitude of the scientific surprise, on a scale of 1 to 10, is pretty large, said Susan Lozier, an oceanographer at Duke University who was lead author of the research published Thursday in Science.

“For me personally, maybe a 7,” she said. “But I think for the community, it might have been more like a 9.”

Read full articlehttps://www.washingtonpost.com/climate-environment/2019/01/31/surprising-new-picture-ocean-circulation-could-have-major-consequences-climate-science/?utm_term=.a6d7bc06d6e6