Tuesday, August 10, 2021

Are We Nearing A Disruption Of The Atlantic Meridional Overturning Circulation

If you have been following Suspicious Observers, you know that last week he discussed some new findings regarding the Atlantic Meridional Overturning Circulation (AMOC) by researchers at the Potsdam Institute For Climate Impact Research and published in Nature Climate Change. The news release concerning the research indicates that "[t]he major Atlantic ocean current, to which also the Gulf stream belongs, may have been losing stability in the course of the last century," and adds: 

The Atlantic Meridional Overturning Circulation, or AMOC, transports warm water masses from the tropics northward at the ocean surface and cold water southward at the ocean bottom, which is most relevant for the relatively mild temperatures in Europe. Further, it influences weather systems worldwide. A potential collapse of this ocean current system could therefore have severe consequences.

Also:

    It has been shown previously that the AMOC is currently at its weakest in more than a 1000 years. However, so far it has remained an open question whether the observed weakening corresponds to a change in the mean circulation state, or whether it is associated with an actual loss of dynamical stability. “The difference is crucial”, says Niklas Boers, “because the loss of dynamical stability would imply that the AMOC has approached its critical threshold, beyond which a substantial and in practice likely irreversible transition to the weak mode could occur.”

    Long-term observational data of the strength of the AMOC does unfortunately not exist, but the AMOC leaves so-called fingerprints in sea-surface temperature and salinity patterns of the Atlantic ocean. “A detailed analysis of these fingerprints in eight independent indices now suggests that the AMOC weakening during the last century is indeed likely to be associated with a loss of stability,” says Boers. ”The findings support the assessment that the AMOC decline is not just a fluctuation or a linear response to increasing temperatures but likely means the approaching of a critical threshold beyond which the circulation system could collapse.” 

(See also "Major Atlantic ocean current system might be approaching critical threshold"--Science Daily (h/t Marcus Wynne)).The major impacts on causing the AMOC to collapse is an influx of fresh water, such as from melting of the icecap, glacial melting, and outflows from rivers. "Freshwater is lighter than saltwater and reduces the tendency of the water to sink from the surface to greater depths, which is one of the drivers of the overturning."

    Of course the article throws out global warming as a potential driver of the production of ice water. Yet, as Ben Davidson of Suspicious Observers has indicated (backed up by scientific papers on the subject), the weakening of the Earth's magnetic field lets more cosmic rays travel deep into the atmosphere, and this is most seen at the magnetic poles. These cosmic rays increase atmospheric temperatures at the poles as well as drive the production of clouds.

    In any event, if the AMOC stops, the result will be global cooling. The Gulf Stream will no longer transport warm water into the North Atlantic, resulting in cooling of northern North America as well as Europe. It will obviously also alter weather patterns in the mid-latitudes. One recent article indicates:

If the AMOC collapsed, it would increase cooling in the Northern Hemisphere, contribute to rising sea levels in the Atlantic, an overall fall in precipitation over Europe and North America and a shift in monsoons in South America and Africa, Britain’s Meteorological or Met Office warned.

 A USA Today article similarly indicates:

    If this circulation shuts down, it could bring extreme cold to Europe and parts of North America, raise sea levels along the U.S. East Coast and disrupt seasonal monsoons that provide water to much of the world, the Washington Post said. 

    It would also further endanger the Amazon rainforest and Antarctic ice sheets, according to the Guardian. 

 A Washington Post article notes that it is believed that the Younger Dryas was the result of a collapse of the AMOC (obviously this ignores a possible impactor or, as Davidson contends, micro-nova event being the cause).

It’s happened before. Studies suggest that toward the end of the last ice age, a massive glacial lake burst through a declining North American ice sheet. The flood of freshwater spilled into the Atlantic, halting the AMOC and plunging much of the Northern Hemisphere — especially Europe — into deep cold. Gas bubbles trapped in polar ice indicate the cold spell lasted 1,000 years. Analyses of plant fossils and ancient artifacts suggest that the climate shift transformed ecosystems and threw human societies into upheaval.

The same article adds:

And the apparent consequences of the AMOC slowing are already being felt. A persistent “cold blob” in the ocean south of Greenland is thought to result from less warm water reaching that region. The lagging Gulf Stream has caused exceptionally high sea level rise along the U.S. East Coast. Key fisheries have been upended by the rapid temperature swings, and beloved species are struggling to cope with the changes.

3 comments:

  1. That's why I kept my Alaska gear. Might have to lose a few pounds, but if that happened, it shouldn't be an issue.

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    Replies
    1. I'm just glad my house came with an efficient fireplace.

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    2. It all depends on perspective I guess. As it is currenty in the low 90's with high humidity where I live - "air you can wear" - TBH I'm hoping and praying that AMOC collapses. To illustrate the point, there is an old tale about Christian missionaries visiting the Inuit and trying to scare them with stories of Hell...lakes of fire and all. The Inuit eagerly asked "How do we get there?"

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A New Defensive Pistolcraft Post ...

  ... from Jon Low . There is a lot of good stuff in this post, and Jon seems (at least to me) to have included much more of his own comment...