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Freegrass

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Atlantification
« on: March 11, 2023, 01:23:22 AM »
I have a question about Atlantification, and was surprised to find there wasn't a dedicated thread about this important process yet.

This was just posted on another thread.

Gero, I agree with you in general - but remember that the heat loss in the Barents is, to a large extent, from Atlantic waters carrying heat up from the mid latitudes and even the tropics.
It reminded me to see if I should update my ocean heat and temperatures file from NOAA data.

It is getting warmer in the North Atlantic


Is it a coincidence that this temperature increase happens at the same time of the start of the AMOC slowdown that you just posted about in the AMOC thread? (see image below)

Is the AMOC slowing down because of the temperature increase in the North Atlantic? Or is the temperature in the North Atlantic and Barents sea increasing because of the AMOC slowdown?

I've wondered about this so much before; If the Gulfstream isn't sinking properly anymore, it must keep moving forward into the Barents sea, right? Is this what's causing a warmer Barents sea and Atlantification to speed up?

I found a part of the answer on Wikipedia, but I still don't understand the entire process of Atlantification yet. I hope to get a better grasp about it here in this new thread, because it's such an important process in the Arctic. Hope someone can help me to figure it all out.

Quote
Process of Atlantification

The increasing influence of Atlantic water flowing into the Arctic Ocean and the loss of stratification causes the warm Atlantic water to mix with the fresh water at the surface. As can be seen in the figure below, the halocline weakens and therefore heat from the Atlantic water reaches the surface. This warming of the surface water causes a retreat in sea-ice in winter and a total absence of sea-ice in summer. The loss of winter sea-ice means that in summer, the colder layer of freshwater at the surface is less replenished by melting ice, lessening the temperature difference between the layers. Also, a lack of sea-ice increases the influence of wind on the sea surface, mixing the layers further.

Model predictions do not show an upward trend in volume transport into the Arctic from the North Atlantic nor an increase in the temperature of the inflowing water leading some to conclude that the Atlantification of the Arctic is not caused by a process in the Atlantic Ocean but rather by atmospheric forcing in the Arctic region, amplified by sea-ice loss.

However observations show a regime shift from winter sea ice cover to open water in the southern Barents Sea in response to the warming of the inflowing Atlantic water. Observations also reveal the increasing influence of Atlantic water heat further to the east, in the eastern Eurasian Basin, where in recent years the heat flux from the Atlantic water towards the surface has overtaken the atmospheric contribution in this region. Furthermore, an observed weakening of the halocline over this period coincided increasing wind driven upper ocean currents, pointing to increased mixing.

Consequences
At the moment, the largest part of inflowing heat from the Atlantic Ocean is lost to the atmosphere within the Barents Sea. It is expected though, that the temperature in the Barents Sea will increase due to changes in the interaction with the atmosphere. As a result, the water flowing out from the Barents Sea in between Franz Josef Land and Novaya Zemlya (Barents Sea exit) will warm significantly from -0.2° to 2.2°C in 2080. This shows that warm Atlantic water will penetrate further into the Arctic Ocean, ultimately extending throughout the Eurasian basin, leading to reduction in sea-ice thickness in this region.

Organisms
Atlantification as part of the climate changing in the Arctic has major consequences for all organisms living there. Due to the warming of Barents Sea, phytoplankton blooms are moving further into the Eurasian Basin each year. Typical species have moved 5 degrees further North compared to 1989. Also, fish communities are moving Northward at the pace of the local climate change, a process called borealization. Some predators that reach areas previously not warm enough change the ecological systems of the Arctic. As a result, Arctic shelf fish are being expelled and retract Northwards as well. For some species, depth might limit their options and this will induce changes in the biodiversity of the Arctic Ocean. This change in marine ecosystem also influences the bird and mammal species living in the Arctic region. Sea birds, seals and whales depend directly on the fish populations. Land mammals like polar bears live on seals and are also strongly dependant on the sea-ice to live on.

Tipping point
There are growing concerns that the Arctic climate might be moving to a so-called tipping point, meaning that if a critical point is reached, the system will settle around a different equilibrium state. In the Arctic this different state could be one with much less or no sea-ice.
« Last Edit: March 11, 2023, 02:03:36 AM by Freegrass »
When computers are set to evolve to be one million times faster and cheaper in ten years from now, then I think we should rule out all other predictions. Except for the one that we're all fucked...

binntho

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Re: Atlantification
« Reply #1 on: March 11, 2023, 07:09:31 AM »
I am not so sure that the AMOC is slowing down - scientists are still arguing about this.
because a thing is eloquently expressed it should not be taken to be as necessarily true
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El Cid

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Re: Atlantification
« Reply #2 on: March 11, 2023, 08:47:26 AM »
I am not so sure that the AMOC is slowing down - scientists are still arguing about this.

As the Economist reported in this week's issue in the Science section:

"So when, in 2005, a paper in Nature reported, on the basis of the five pertinent shipborne surveys which had been made since 1957, a 30% drop in the volume of AMOC between 1992 and 2004, there was serious concern… As it happened, though, 2004 was a turning-point in observations of what is going on, for it saw the beginning of the deployment of a set of recording instruments which are now known as RAPID AMOC. These monitor the Atlantic a couple of degrees north of the Tropic of Cancer, the part of the world where the surveys reported in the Nature paper had been conducted. RAPID AMOC was joined in 2014 by an Arctic counterpart, OSNAP, the Overturning in the Subpolar North Atlantic Programme.
The upshot has been the discovery that the rate of overturning can vary, apparently at random, as much as six-fold during the course of a year. The fall described in the Nature paper was an artefact of an impoverished data set."


binntho

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Re: Atlantification
« Reply #3 on: March 11, 2023, 09:14:56 AM »
Thanks for that El Cid. Also note that we are talking about the tropic of cancer here, and not the tiny part of the Atlantic that stretches north of Iceland and is the one we should be worrying about in the context of Arctic Sea Ice and possible Atlantification of parts of the Actic Ocean.

The surface heat distribution charts over the last decade or so have shown a consistent "cold blob" south of Greenland, while the Atlantic north of Iceland has been consistently warm.
because a thing is eloquently expressed it should not be taken to be as necessarily true
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HapHazard

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Re: Atlantification
« Reply #4 on: March 12, 2023, 06:38:51 AM »
Quote
This probably needs editing I'll check in the morning.
Well, it could probably use a paragraph break or two, at least. haha :)
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johnm33

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Re: Atlantification
« Reply #5 on: March 12, 2023, 10:05:32 AM »
Quote
This probably needs editing I'll check in the morning.
Well, it could probably use a paragraph break or two, at least. haha :)
Needs a rewrite too incoherent at the end, mustn't drink and drivel.

vox_mundi

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Re: Atlantification
« Reply #6 on: September 02, 2023, 02:36:20 AM »
New Research Explains 'Atlantification' of the Arctic Ocean
https://phys.org/news/2023-09-atlantification-arctic-ocean.html

New research by an international team of scientists explains what's behind a stalled trend in Arctic Ocean sea ice loss since 2007. The findings indicate that stronger declines in sea ice will occur when an atmospheric feature known as the Arctic dipole reverses itself in its recurring cycle.

The many environmental responses to the Arctic dipole are described in a paper published online today in the journal Science. This analysis helps explain how North Atlantic water influences Arctic Ocean climate. Scientists call it Atlantification.

... "This is a multidisciplinary view on what's going on in the Arctic and beyond," Polyakov said of the new research. "Our analysis covered the atmosphere, ocean, ice, changing continents and changing biology in response to climate change."

A wealth of data, including direct instrumental observations, reanalysis products and satellite information going back several decades, shows that the Arctic dipole alternates in an approximately 15-year cycle and that the system is probably at the end of the present regime.

In the Arctic dipole's present "positive" regime, which scientists say has been in place since 2007, high pressure is centered over the Canadian sector of the Arctic and produces clockwise winds. Low pressure is centered over the Siberian Arctic and features counterclockwise winds.

This wind pattern drives upper ocean currents, with year-round effects on regional air temperatures, atmosphere-ice-ocean heat exchanges, sea-ice drift and exports, and ecological consequences.

The authors write that, "Water exchanges between the Nordic seas and the Arctic Ocean are critically important for the state of the Arctic climate system" and that sea ice decline is "a true indicator of climate change."



In analyzing oceanic responses to the wind pattern since 2007, the researchers found decreased flow from the Atlantic Ocean into the Arctic Ocean through the Fram Strait east of Greenland, along with increased Atlantic flow into the Barents Sea, located north of Norway and western Russia.

The new research refers to these alternating changes in the Fram Strait and the Barents Sea as a "switchgear mechanism" caused by the Arctic dipole regimes.

The researchers also found that counterclockwise winds from the low-pressure region under the current positive Arctic dipole regime drive freshwater from Siberian rivers into the Canadian sector of the Arctic Ocean.

This westward movement of freshwater from 2007 to 2021 helped slow the overall loss of sea ice in the Arctic compared to 1992 through 2006. The freshwater layer's depth increased, making it too thick and stable to mix with the heavier saltwater below. The thick layer of freshwater prevents the warmer saltwater from melting sea ice from the bottom.

The authors write that the switchgear mechanism regulating inflows of sub-Arctic waters has "profound" impacts on marine life. It can lead to potentially more suitable living conditions for sub-Arctic boreal species near the eastern part of the Eurasian Basin, relative to its western part.

Quote
... "We are beyond the peak of the currently positive Arctic dipole regime, and at any moment it could switch back again," ... "This could have significant climatological repercussions, including a potentially faster pace of sea-ice loss across the entire Arctic and sub-Arctic climate systems."

Igor V. Polyakov et al, Fluctuating Atlantic inflows modulate Arctic atlantification, Science (2023).
https://www.science.org/doi/10.1126/science.adh5158

Sheldon Bacon, Arctic sea ice, ocean, and climate evolution, Science (2023)
https://www.science.org/doi/10.1126/science.adj8469

Abstract

Enhanced warm, salty subarctic inflows drive high-latitude atlantification, which weakens oceanic stratification, amplifies heat fluxes, and reduces sea ice. In this work, we show that the atmospheric Arctic Dipole (AD) associated with anticyclonic winds over North America and cyclonic winds over Eurasia modulates inflows from the North Atlantic across the Nordic Seas. The alternating AD phases create a “switchgear mechanism.” From 2007 to 2021, this switchgear mechanism weakened northward inflows and enhanced sea-ice export across Fram Strait and increased inflows throughout the Barents Sea. By favoring stronger Arctic Ocean circulation, transferring freshwater into the Amerasian Basin, boosting stratification, and lowering oceanic heat fluxes there after 2007, AD+ contributed to slowing sea-ice loss. A transition to an AD− phase may accelerate the Arctic sea-ice decline, which would further change the Arctic climate system.
« Last Edit: September 02, 2023, 02:42:31 AM by vox_mundi »
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Freegrass

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Re: Atlantification
« Reply #7 on: September 02, 2023, 05:51:54 AM »
Excellent post Vox! Now we finally have an explanation for the stepped graph we have been talking so much about. Next year could be very interesting with a possible shift in this pattern and El Niño.

I'm curious if the cloudy weather that we've had for the last 3 years is a signal that this change is about to happen.
When computers are set to evolve to be one million times faster and cheaper in ten years from now, then I think we should rule out all other predictions. Except for the one that we're all fucked...

Freegrass

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Re: Atlantification
« Reply #8 on: December 25, 2023, 04:57:52 PM »
I am not so sure that the AMOC is slowing down - scientists are still arguing about this.

Apparently it is, and we need to understand this better if we want to understand Atlantification better...

Quote
Arctic sea ice extent would have been even lower, had the Atlantic meridional overturning circulation (AMOC) not been slowing down. As a result of AMOC's slowing down, less ocean heat is reaching the Arctic Ocean. Instead, a huge amount of ocean heat has been accumulating in the North Atlantic and much of this heat could soon be pushed abruptly into the Arctic Ocean as storms temporarily speed up currents that carry ocean heat into the Arctic Ocean.
https://arctic-news.blogspot.com/2023/12/double-blue-ocean-event-2024.html
When computers are set to evolve to be one million times faster and cheaper in ten years from now, then I think we should rule out all other predictions. Except for the one that we're all fucked...

binntho

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Re: Atlantification
« Reply #9 on: December 26, 2023, 06:43:54 AM »
I am not so sure that the AMOC is slowing down - scientists are still arguing about this.

Apparently it is, and we need to understand this better if we want to understand Atlantification better...

Quote
Arctic sea ice extent would have been even lower, had the Atlantic meridional overturning circulation (AMOC) not been slowing down. As a result of AMOC's slowing down, less ocean heat is reaching the Arctic Ocean. Instead, a huge amount of ocean heat has been accumulating in the North Atlantic and much of this heat could soon be pushed abruptly into the Arctic Ocean as storms temporarily speed up currents that carry ocean heat into the Arctic Ocean.
https://arctic-news.blogspot.com/2023/12/double-blue-ocean-event-2024.html

The linked site is not really very trustworthy. I used to look at it regularly, but their over-the-top doom mongering just gets tiring, and their scientific credibility is not very high.

There is still no consensus on whether the Gulf stream is slowing down, particularly the part that extends past Scotland and Iceland towards Norway and eventually into the Arctic (the Norwegian current).
because a thing is eloquently expressed it should not be taken to be as necessarily true
St. Augustine, Confessions V, 6