Please select your home edition
Edition
Sailing Holidays 2019 - TOP

Fingerprint of ancient abrupt climate change found in Arctic

by The Woods Hole Oceanographic Institution 15 Jul 2018 17:28 UTC
In 2013, a team of researchers set sail to the eastern Beaufort Sea in search of evidence for the flood near where the Mackenzie River enters the Arctic Ocean, forming the border between Canada's Yukon and Northwest territories. © Lloyd Keigwin, Woods Hole Oceanographic Institution

A research team led by Woods Hole Oceanographic Institution (WHOI) found the fingerprint of a massive flood of fresh water in the western Arctic, thought to be the cause of an ancient cold snap that began around 13,000 years ago.

"This abrupt climate change—known as the Younger Dryas—ended more than 1,000 years of warming," explains Lloyd Keigwin, an oceanographer at WHOI and lead author of the paper published online July 9, 2018, in the journal Nature Geoscience.

The cause of the cooling event, which is named after a flower (Dryas octopetala) that flourished in the cold conditions in Europe throughout the time, has remained a mystery and a source of debate for decades.

Many researchers believed the source was a huge influx of freshwater from melting ice sheets and glaciers that gushed into the North Atlantic, disrupting the deep-water circulation system—Atlantic Meridional Overturning Circulation (AMOC)— that transports warmer waters and releases heat to the atmosphere. However, geologic evidence tracing its exact path had been lacking.

In 2013, a team of researchers from WHOI, Scripps Institution of Oceanography at the University of California San Diego, and Oregon State University, set sail to the eastern Beaufort Sea in search of evidence for the flood near where the Mackenzie River enters the Arctic Ocean, forming the border between Canada's Yukon and Northwest territories. From aboard the U.S. Coast Guard Cutter Healy, the team gathered sediment cores from along the continental slope east of the Mackenzie River. After analyzing the shells of fossil plankton found in the sediment cores, they found the long sought-after geochemical signal from the flood.

"The signature of oxygen isotopes recorded in foraminifera shells preserved in the sediment allowed us to fingerprint the source of the glacial lake discharge down the MacKenzie River 13,000 years ago," said co-principal investigator Neal Driscoll, a professor of geology and geophysics at Scripps Oceanography. "Radiocarbon dating on the shells provided the age constraints. Circulation models for the Arctic Ocean reveal that low-salinity surface water is efficiently transported to the North Atlantic. How exciting it is when the pieces of a more than 100-year puzzle come together."

Next steps in future research, Keigwin says, will be for scientists to answer remaining questions about the quantity of fresh water delivered to the North Atlantic preceding the Younger Dryas event and over how long of a period of time.

"Events like this are really important, and we have to understand them better," adds Keigwin. "In the long run, I think the findings from this paper will stimulate more research on how much fresh water is really necessary to cause a change in the system and weakening of the AMOC. It certainly calls further attention to the warming we're seeing in the Arctic today, and the accelerated melting of Greenland ice."

Earlier this year, a paper by researchers at the University College London and WHOI found evidence that the AMOC hasn't been running at peak strength since the mid-1800s and is currently at its weakest point in the past 1,600 years. Continued weakening could disrupt weather patterns from the U.S. and Europe to the African Sahel.

Additional co-authors of the paper published in Nature Geoscience are: Ning Zhao and Liviu Giosan of WHOI; Shannon Klotsko of Scripps Oceanography; and Brendan Reilly of Oregon State University.

This work was supported by a grant from the National Science Foundation, Office of Polar Programs.

For more information, please visit www.whoi.edu.

This article has been provided by the courtesy of Woods Hole Oceanographic Institution.

Related Articles

For now, river deltas gain land worldwide
Delta areas worldwide have actually gained land in the past 30 years Researchers from Utrecht University in the Netherlands, Woods Hole Oceanographic Institution (WHOI), and colleagues found that delta areas worldwide have actually gained land in the past 30 years, despite river damming. Posted on 26 Jan
How microbes reflect the health of coral reefs
Microorganisms play important roles in the health and protection of coral reefs Microorganisms play important roles in the health and protection of coral reefs, yet exploring these connections can be difficult due to the lack of unspoiled reef systems throughout the global ocean. Posted on 22 Dec 2019
DISCO allows scientists to measure superoxide
Superoxide is a reactive chemical that is a byproduct within all photosynthesizing organisms Researchers at Woods Hole Oceanographic Institution (WHOI) successfully conceived and tested a portable device, DISCO, that performed the first in situ measurements of a highly reactive type of oxygen, known as superoxide Posted on 13 Dec 2019
Sunlight degrades polystyrene faster than expected
Sunlight can transform the polystyrene into CO2 A study published by researchers at WHOI shows that polystyrene, one of the world's most ubiquitous plastics, may degrade in decades or centuries when exposed to sunlight, rather than thousands of years as previously thought. Posted on 13 Oct 2019
How much of corals' nutrition comes from hunting?
Most of their nutrients come from microscopic algae living inside of them When it comes to feeding, corals have a few tricks up their sleeve. Most of their nutrients come from microscopic algae living inside of them, but if those algae aren't creating enough sustenance, corals can use their tentacles to grab and eat Posted on 19 Sep 2019
No direct link between currents & sea level
Study into North Atlantic currents and sea level along New England coast A new study by the Woods Hole Oceanographic Institution (WHOI) clarifies what influence major currents in the North Atlantic have on sea level along the northeastern United States. Posted on 17 Jun 2019
Construction begins on regional research vessel
WHOI takes part in keel-laying ceremony for ECOC new vessel Officials from the WHOI took part in a keel-laying ceremony this week to mark the start of construction of the R/V Resolution, a new $125 million Regional Class Research Vessel (RCRV) funded by the National Science Foundation (NSF). Posted on 13 May 2019
Microbes may act as gatekeepers of deep carbon
Microbes consume, and crucially help trap, a small amount of sinking carbon Two years ago an international team of scientists visited Costa Rica's subduction zone, where the ocean floor sinks beneath the continent and volcanoes tower above the surface. Posted on 28 Apr 2019
New deep-sea coral species discovered in Atlantic
By Woods Hole Oceanographic Institution scientists in Atlantic Marine Monument DNA analysis recently confirmed that Woods Hole Oceanographic Institution (WHOI) scientists and their collaborators at OceanX, the University of Connecticut (UConn), and NASA's Jet Propulsion Laboratory (JPL) discovered two new species of deep-sea corals. Posted on 13 Apr 2019
New report explores threats impacting right whales
The North Atlantic right whale is a critically endangered whale species The North Atlantic right whale is a critically endangered whale species that is protected under the U.S. Endangered Species Act, the Marine Mammal Protection Act, and Canada's Species at Risk Act. Posted on 31 Mar 2019
Sailing Holidays 2019 - BOTTOMMarine Resources 2019 - FooterVaikobi 2019AUG - Footer 1