Loss of Arctic sea ice impacting Atlantic Ocean water circulation system

July 31, 2017

New Haven, Conn. - Arctic sea ice is not merely a passive responder to the climate changes occurring around the world, according to new research.

Scientists at Yale University and the University of Southampton say the ongoing Arctic ice loss can play an active role in altering one of the planet's largest water circulation systems: the Atlantic Meridional Overturning Circulation (AMOC).

AMOC has a lower limb of dense, cold water that flows south from the north Atlantic, and an upper limb of warm, salty water that flows north from the south Atlantic as part of the Gulf Stream. AMOC plays a major role in regional and global climate, affecting the Atlantic rim countries -- particularly those in Europe -- and far beyond. It was featured in the movie "The Day After Tomorrow."

"Conventional thinking has been that if ocean circulation weakens, reducing the transport of heat from low to high latitudes, then it should lead to sea ice growth. But we have found another, overlooked, mechanism by which sea ice actively affects AMOC on multi-decadal time scales," said professor Alexey Fedorov, climate scientist at the Yale Department of Geology and Geophysics and co-author of a study detailing the findings in the journal Nature Climate Change.

The first author of the paper is Florian Sévellec, a former Yale postdoctoral researcher in Fedorov's lab who is now an associate professor at the University of Southampton. Wei Liu, a Yale postdoctoral associate, is another co-author of the study.

Earlier this year, a different Yale-led study cautioned that the AMOC system was not as stable as previously thought. That study said the possibility of a collapsed AMOC under global warming conditions is being significantly underestimated.

"We've now found this new connection between sea ice and AMOC," Liu said. "Sea ice loss is clearly important among the mechanisms that could potentially contribute to AMOC collapse."

The researchers based their findings on a combination of comprehensive climate model simulations and novel computations of the sensitivity of ocean circulation to fluctuations in temperature and salinity at the ocean's surface over time.

"In our experiments we saw a potential loss of 30% to 50% of AMOC's strength due to Arctic sea ice loss. That is a significant amount, and it would accelerate the collapse of AMOC if it were to occur," Fedorov said.

In the short-term, changes in the subpolar North Atlantic have the greatest impact on AMOC, the researchers found; but over the course of multiple decades, it was changes in the Arctic that became most important to AMOC, they said.

"We suggest that Arctic changes on a multi-decadal timescale, such as the decline in sea ice cover that we are currently experiencing, is the most efficient way to weaken the large-scale ocean circulation of the North Atlantic, which is responsible for the oceanic transport of heat from the equator to high latitudes," Sévellec said.
-end-
Grants from the U.S. Department of Energy Office of Science, the National Oceanic and Atmospheric Administration, and the Natural and Environmental Research Council UK supported the research.

Yale University

Related Sea Ice Articles from Brightsurf:

2020 Arctic sea ice minimum at second lowest on record
NASA and the National Snow and Ice Data Center (NSIDC) at the University of Colorado Boulder shows that the 2020 minimum extent, which was likely reached on Sept.

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 much will polar ice sheets add to sea level rise?
Over 99% of terrestrial ice is bound up in the ice sheets covering Antarctic and Greenland.

A snapshot of melting Arctic sea ice during the summer of 2018
A study appearing July 29 in the journal Heliyon details the changes that occurred in the Arctic in September of 2018, a year when nearly 10 million kilometers of sea ice were lost throughout the summer.

Antarctic penguins happier with less sea ice
Researchers have been surprised to find that Adélie penguins in Antarctica prefer reduced sea-ice conditions, not just a little bit, but a lot.

Seasonal sea ice changes hold clues to controlling CO2 levels, ancient ice shows
New research has shed light on the role sea ice plays in managing atmospheric carbon dioxide levels.

Artificial intelligence could revolutionize sea ice warnings
Today, large resources are used to provide vessels in the polar seas with warnings about the spread of sea ice.

Antarctic sea ice loss explained in new study
Scientists have discovered that the summer sea ice in the Weddell Sea sector of Antarctica has decreased by one million square kilometres -- an area twice the size of Spain -- in the last five years, with implications for the marine ecosystem.

Antarctic sea-ice models improve for the next IPCC report
All the new coupled climate models project that the area of sea ice around Antarctica will decline by 2100, but the amount of loss varies considerably between the emissions scenarios.

Earth's glacial cycles enhanced by Antarctic sea-ice
A 784,000 year climate simulation suggests that Southern Ocean sea ice significantly reduces deep ocean ventilation to the atmosphere during glacial periods by reducing both atmospheric exposure of surface waters and vertical mixing of deep ocean waters; in a global carbon cycle model, these effects led to a 40 ppm reduction in atmospheric CO2 during glacial periods relative to pre-industrial level, suggesting how sea ice can drive carbon sequestration early within a glacial cycle.

Read More: Sea Ice News and Sea Ice Current Events
Brightsurf.com 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 Amazon.com.