Taxonomy term

circulation

How the Arctic became salty

The Arctic Ocean hasn’t always been as salty as other oceans. In the Eocene, between 56 million and 34 million years ago, the water surrounding the North Pole — freshened by melt from sea ice and river runoff — was cut off from the Atlantic and Pacific oceans by land bridges. At some point, plate tectonic processes opened the North Atlantic, submerging the land bridges and allowing saltwater to pour into the Arctic, but the timing and details of these events are largely unknown. New research suggests a tipping point may have been reached as one particular land bridge submerged far enough below the ocean surface.

25 Sep 2017

Ice (Re)Cap: May 2017

From Antarctica to the Arctic; from polar caps, permafrost and glaciers to ocean-rafted sea ice; and from burly bears to cold-loving microbes, fascinating science is found in every nook and crevasse of Earth’s cryosphere, and new findings are announced often. Here are a few of the latest updates.

12 May 2017

A new — and more toxic — normal? Harmful algal blooms find new habitats in changing oceans

A massive and deadly algal bloom along the West Coast of North America in 2015 is just one example of the growing number of severe algal blooms that are occurring throughout the world's oceans. Scientists are studying how toxic species are adjusting to a warming climate. 

16 Jan 2017

Atmosphere, more than ocean, might drive Atlantic climate variation

Atmospheric, not oceanic, circulation may be the main driver of climate variations over the North Atlantic Ocean, potentially complicating future hurricane and drought predictions, according to the authors of a new study.
 
01 Feb 2016

Southbound icebergs off the hook for ice-age cooling

During the Late Pleistocene, changes in North Atlantic Ocean circulation triggered abrupt changes in global climate: In some locations in the Northern Hemisphere, average temperatures dropped by as much as 10 degrees Celsius within a few decades. Scientists have long thought that freshwater from melting icebergs traveling south from the Arctic may have instigated the circulation shifts that contributed to cooling feedback loops. But now, scientists looking at seafloor sediments collected near Iceland have found that pulses of icebergs typically arrived after the onset of cooling episodes, too late to be primary drivers of climate change.
 
11 Aug 2015

Hydrogen chloride on the rise in Northern Hemisphere skies

Levels of the atmospheric pollutant hydrogen chloride have increased substantially in the lower stratosphere over the Northern Hemisphere since 2007, according to a new study. The increase, however, is not due to an influx of chlorine, but rather to a side effect of the recent slowing of stratospheric circulation that was first reported in 2005.
 
02 Jul 2015

Ocean waves explain which La Niña events will linger

Cattle scavenging parched landscapes in search of tufts of crispy grass were the iconic image of the Texas drought in the winter of 2011. Record dry conditions inflicted nearly $8 billion in economic losses on the state’s agricultural sector before April showers brought a scant dose of relief. By fall, however, it became clear that warm, dry weather would return the following winter thanks to a persistent weather pattern in the tropical Pacific known as La Niña.

21 Jul 2014

Voyage to the plastic vortex

Out in the middle of the northern Pacific Ocean, a giant floating mess of plastic debris is drifting and bobbing among the waves. Scientists call this expanse of litter, which stretches for hundreds of kilometers across open sea, the Great Pacific Garbage Patch. But before last summer, there was little information about how large the patch really is, what types of debris are out there and what kind of impact it is having on ocean life.

03 Sep 2009