Melting Greenland ice sheet may affect global ocean circulation, future climate

January 22, 2016
Isua Supracrustal Belt Isua, south-west Greenland. Credit: University of Washington.

Scientists from the University of South Florida, along with colleagues in Canada and the Netherlands, have determined that the influx of fresh water from the Greenland ice sheet is "freshening" the North Atlantic Ocean and could disrupt the Atlantic Meridional Overturning Circulation (AMOC), an important component of global ocean circulation that could have a global effect. Researchers say it could impact the future climate in places such as portions of Europe and North America.

Their study on the influence of freshwater influx on Labrador Sea convection and Atlantic circulation is published in a new issue of the journal Nature Communications.

"We derived a new estimate of recent freshwater flux from Greenland using updated GRACE satellite data," said USF professor Tim Dixon. "The data suggest that the influx of freshwater from Greenland is accelerating, and has changed the Labrador Sea in ways that could lead to a weakening of the AMOC."

Freshwater flux from Greenland is composed of melt runoff from ice and tundra runoff as well as ice discharge ("calving" of icebergs). The amount of freshwater flux from Greenland was relatively stable from the late 1970's to the mid 1990's, and then began to increase. Increased freshwater flux could weaken the AMOC, resulting in a number of consequences, both local and global, said the researchers.

"Focused freshwater flux into the Labrador Sea has the potential to increase the buoyancy of surface waters and reduce formation of dense, deep water that helps drive the overturning circulation," said co-author Don Chambers , USF College of Marine Science associate professor.

How much of the enhanced freshwater flux actually winds up in the Labrador Sea?

Because of the clockwise nature of around Greenland, most of the freshwater increase, up to 70 percent, is being driven toward the Labrador Sea, magnifying its impact and increasing the possibility of significant effects on the AMOC, said Qian Yang, the paper's first author and a PhD student at USF whose dissertation, in part, includes this research.

According to the researchers, not only are changes in the AMOC difficult to measure, it's also difficult to separate natural climatic variation from climate changes induced by human activity.

The potential consequences of a weakened AMOC include changes in climate.

"The AMOC transports a large amount of heat into the North Atlantic where it is given up to the atmosphere and helps regulate the climate in Europe and North America. The major effect of a slowing AMOC is expected to be cooler winters and summers around the North Atlantic, and small regional increases in sea level on the North American coast," explained Chambers.

According to Dixon, the global impacts are less certain, but potentially more consequential.

"The AMOC and Gulf Stream are part of a complex system that is still not completely understood," said Dixon. "If human activities are starting to impact this system, it is a worrying sign that the scale of human impacts on the climate system may be reaching a critical point."

Continued long-term observation is required to understand the impact of the freshwater influx.

"This shows the need to continue to look at different components of the climate system, including the ice sheets and oceans, in an integrated sense," concluded Paul Myers, study co-author and Professor of Oceanography at the University of Alberta.

Explore further: Agulhas Current leakage could stabilize Atlantic overturning circulation

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HannesAlfven
1.4 / 5 (10) Jan 22, 2016
The key point to realize about this idea is that scientists have been TRYING to make this claim for many years now. They tried to insert it into the Firestone narrative about a recent large-scale cosmic event, as well, and I'm sure it's popped up in many other places as well.

This speaks more to the idea's palatability for the mainstream and its marketing than anything else. Just as likely -- but less palatable, since it involves questioning the framework itself -- is that the ocean circulation is affected by the Earth's plasma environment. After all, salt water is conductive, and the plasma nature of the Earth's environment was the most significant observation of the Space Age made when we first started sending rockets into space.
Scroofinator
1.8 / 5 (5) Jan 22, 2016
Just wait until a huge iceberg breaks off and floats into the current, then the real changes will begin.
jeffensley
2 / 5 (8) Jan 22, 2016
According to the researchers, not only are changes in the AMOC difficult to measure, it's also difficult to separate natural climatic variation from climate changes induced by human activity.


That's really all that needs to be said. Observe and adapt... our prognostications just aren't that valuable.

Read more at: http://phys.org/n...html#jCp
gkam
2.5 / 5 (19) Jan 22, 2016
jeff is unaware of the scale of the consequences.
jeffensley
2.3 / 5 (9) Jan 22, 2016
The consequences could range from dire to beneficial, with everything in between. We are likely to see all of these things. It's just not that much different from daily life. You seem unaware of our inability to effect any measurable changes to such large-scale forces nor the folly in our attempts.
Paulw789
1.9 / 5 (9) Jan 22, 2016
Because of this additional fresh water influx, the salinity of the ocean in the area has changed by exactly Zero. That is a huge impact.
HeloMenelo
2.2 / 5 (13) Jan 22, 2016
aaaahhh looki here antisciencegorilla's sockpuppets jeffey and uncle screwed in all their big furry jimbo glory....mmmmm.....i'm up for a good game of ping pong, and you gonna be our bouncy ball for the weekend yes... :D actually i see u already have been bouncing back and forth quite a lot on the other sections this week with all your sockpuppets, (but that's your standard reputation throughout the years eh..) aaaa what can we say, we like them shiny noses, so we'll keep adding that special shine on it for you, it's a win win for us. unfortunately can't say ther same for you and your puppets... ;) :D :D
rhugh1066
2.3 / 5 (3) Jan 22, 2016
With all the manmade heat absorbing into the top and the cold glacial meltwater sinking to the bottom, the AMOC should flow better than ever, right? =)
runrig
5 / 5 (11) Jan 22, 2016
With all the manmade heat absorbing into the top and the cold glacial meltwater sinking to the bottom, the AMOC should flow better than ever, right? =)


No, the driver is the salty southern waters cooling and sinking. An overlying layer of fresh water prevents that. Can't flow over it to get further north - salty water denser, yes?
Whydening Gyre
4.6 / 5 (14) Jan 22, 2016
With all the manmade heat absorbing into the top and the cold glacial meltwater sinking to the bottom, the AMOC should flow better than ever, right? =)

The fresh water probly isn't as cold as the salinated layers underneath it...

No, the driver is the salty southern waters cooling and sinking. An overlying layer of fresh water prevents that. Can't flow over it to get further north - salty water denser, yes?

A question - is there possibly a current flow of the colder water UNDER the less dense freshwater?

BTW - COULD seems to be the operative word in the first paragraph of the article...
philstacy9
1.6 / 5 (7) Jan 22, 2016
This hypothesis can be tested by waiting to see if it really happens. It would be unscientific to try to alter climate while waiting for this experiment to complete.
gkam
1.8 / 5 (15) Jan 22, 2016
I contend that if philstacy9 puts a six-shot revolver to his head with one bullet in it and pulls the trigger, there is about a 17% chance it can kill him.

"This hypothesis can be tested by waiting to see if it really happens. It would be unscientific to try to alter anything while waiting for this experiment to complete."
greenonions
4.6 / 5 (10) Jan 22, 2016
It would be unscientific to try to alter climate while waiting for this experiment to complete.

Oooops - we better stop burning them fossil fuels right?
runrig
5 / 5 (6) Jan 23, 2016
A question - is there possibly a current flow of the colder water UNDER the less dense freshwater?


Yes, i suppose it could, depending on the depth of lower salinity water at the surface.
Point is though that the salty southern water loses it's heat via radiation to space and not mixing. So it needs to stay at the surface and travel as far north a possible unimpeded.
Scroofinator
3.4 / 5 (5) Jan 23, 2016
I contend that if philstacy9 puts a six-shot revolver to his head with one bullet in it and pulls the trigger, there is about a 17% chance it can kill him.

Weird gkam, weird.....

How does a comment such as this get allowed?
gkam
1.3 / 5 (13) Jan 23, 2016
Scroof, there was no malice in that statement of odds and the ability to predict based on history. The lesson is, we cannot take the chance on AGW being valid, no matter the perceived odds.

gkam
1.3 / 5 (14) Jan 23, 2016
"How does a comment such as this get allowed?"
---------------------------------------------

It was an elucidation of circumstances where one choice is unthinkable. This guy suggested we wait to see if AGW really does kill us.

Go ahead, take his side.
philstacy9
1.7 / 5 (6) Jan 23, 2016
Why not have two versions of this site, one for real scientists and one for communist lite progressives who prefer a wishful thinking world.
gkam
1.3 / 5 (13) Jan 23, 2016
philstacy, I got my opinion by earning a degree in the subject. How did you get yours?
philstacy9
2.8 / 5 (9) Jan 23, 2016
A degree in suicide? An imaginary gun will not harm me even if all the imaginary chambers are loaded with imaginary bullets like nudged data leans into your tinfoil hat disaster scenario but will not harm the earth. Nobody knows how to control climate because there are no experiments showing this can be done. You are trying to compel everyone to live according to your fears which are only supported by predictive models that fail to agree. I have seen hurricane tracks from predictive models that wildly disagree over a time span of a few days but such models extended to decades and used to guide global economics only proves a degree does not track common sense.
gkam
1.3 / 5 (13) Jan 23, 2016
No, the Degree is a Master of Science in Environmental Management, centered on
Energy and the Environment. I have watched as the problems we identified in 1980 have gotten to be serious much faster than we originally feared.

None if us expected the Deniers, fed and driven by Big Money using political prejudice dressed up as skeptical science to manipulate those who want to believe others are wrong, no matter the discussion.
philstacy9
1.7 / 5 (6) Jan 23, 2016
I am glad you brought up money because science is seriously underfunded these days. There is no moon colony or mission to mars and budgets are cut every year to fund EBT cards. Scientists are less in demand in this recession prone economic climate. Some scientists such as climate scientists are worth relatively less to society and can only work in academic settings where they occasionally get a grant to study ice cores or tree rings. However, if climate scientists can convince the public of imminent climate disaster suddenly they are valuable employees doing important work and money flows to them. The agreement on climate change is agreement on bigger paychecks. They know which way the wind blows.
gkam
1.5 / 5 (15) Jan 23, 2016
We could have had it all for the cost of the Bush/Blair Mass Killings for Mass Corporate Profit and Political Advantage.
philstacy9
3 / 5 (6) Jan 23, 2016
I am glad you brought up mass killings. Imagine how this is going to impact carbon sequestration:

http://www.washin...page=all
gkam
1.4 / 5 (11) Jan 23, 2016
It will slow it down.

EMP is not new. We worried about it in the late 1970's when out official policy was "In case of nuclear attack, get out of town". I worked on Crisis Relocation and the protection of industrial assets in nuclear war back then.

Most folk do not understand the dual nature of EM, and think their electrostatic shielding will save them, but it will not.
Scroofinator
5 / 5 (1) Jan 24, 2016
I'm not taking sides gkam, I agree with both of you to a point.

The comment is just unnecessary
Mike_Massen
1.7 / 5 (11) Jan 25, 2016
philstacy9 suggested
This hypothesis can be tested by waiting to see if it really happens
Please try to get a grip, for >100yrs humans have developed keen understanding of heat, one aspect radiative transfer (so far) never refuted despite very best attempts of the anti-AGW deniers as its clearly soundly at core of AGW
https://en.wikipe...transfer
which again irrefutably leads to
https://en.wikipe..._forcing
well illustrated
http://cbc.arizon.../sim/gh/

Look at relationship of CO2 ppm re radiative forcing, now ~1.6W/m^2 & RISING & all WHILE the Sun's output has been declining
http://www.skepti...asic.gif

AND
You want to WAIT so Sun's output inevitably rises & we get a double Whammy, that SANE ?

philstacy9 claims
.. unscientific to try to alter climate while waiting for this experiment..
FFS So, much smarter stop adding more CO2 !

gkam most abrupt but, correctly comparable !
MikPetter
2.7 / 5 (7) Jan 26, 2016
For those interested in science a good article about links between AMOC collapse and warming trends
http://www.nature...shared=0

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