North Atlantic played pivotal role in last great climate tipping point 

Posted: April 6, 2016 by oldbrew in climate, Ocean dynamics, research
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Rinks Glacier, West Greenland  [image credit: NSIDC]

Rinks Glacier, West Greenland
[image credit: NSIDC]


A new angle on glaciations perhaps, but HeritageDaily quotes one of the researchers: ‘The mechanism driving these expansions of southern sourced water into the deep Atlantic still needs working on.’

The North Atlantic Ocean played a key role in the last great tipping point in Earth’s climate system, pioneering new research has shown. An international research team has discovered ground-breaking new reasons why large continental ice-sheets first grew in North America and Scandinavia during the late Pliocene Epoch era, 2.7 millions of years ago.

The collaborative team was led by Dr Ian Bailey from the University of Exeter and Prof Paul Wilson from the University of Southampton, and also involved scientists from Woods Hole Oceanographic Institute in the USA and GEOMAR in Germany. The researchers measured the composition of isotopes of the chemical element neodymium that can be found in fish teeth preserved in a North Atlantic marine core to track the origin of deep waters bathing the bottom of the Atlantic Ocean during this climate transition.

For the past 2.7 million years Earth’s climate has switched more than 50 times between a cold glacial state and warm interglacial state much like today. Contrary to previous assertions, they found that the first of these glacial events in the northern hemisphere were associated with major expansions of carbon-rich southern-sourced deep waters into the northwestern Atlantic abyss, over one million years earlier than previously thought.

The team also found that three of the largest glacial cycles between 2.5 and 2.7 million years ago appear to be associated with southern-sourced water incursions into the deep Atlantic that were as significant as those documented for the last glacial maximum.

The research is published in leading scientific journal, Nature Geoscience, on Monday, 4 April 2016. Dr Bailey, a Geology Lecturer from the Camborne School of Mines, based at the University of Exeter’s Penryn Campus in Cornwall said: “We could not have made these new findings with confidence using only a classic method for tracing watermass origin such as carbon isotopes.

“But when we combined such data with an alternative novel proxy such as neodymium isotopes, we were able to reveal a dramatically new picture of water mass mixing in the deep North Atlantic during late Pliocene glacial intensification.”

Full report: North Atlantic played pivotal role in last great climate tipping point – HeritageDaily – Heritage & Archaeology News

Comments
  1. ren says:

    April 8 will be another attack frosty air in the eastern United States. There will be losses in orchards.

  2. ren says:

    Such a pressure distribution in the lower stratosphere will result in a further drop in temperature at the European Atlantic.

  3. ren says:

    Ice-penetrating radar1, 2, 3 and ice core drilling4 have shown that large parts of the north-central Greenland ice sheet are melting from below. It has been argued that basal ice melt is due to the anomalously high geothermal flux1, 4 that has also influenced the development of the longest ice stream in Greenland1. Here we estimate the geothermal flux beneath the Greenland ice sheet and identify a 1,200-km-long and 400-km-wide geothermal anomaly beneath the thick ice cover. We suggest that this anomaly explains the observed melting of the ice sheet’s base, which drives the vigorous subglacial hydrology3 and controls the position of the head of the enigmatic 750-km-long northeastern Greenland ice stream5. Our combined analysis of independent seismic, gravity and tectonic data6, 7, 8, 9 implies that the geothermal anomaly, which crosses Greenland from west to east, was formed by Greenland’s passage over the Iceland mantle plume between roughly 80 and 35 million years ago. We conclude that the complexity of the present-day subglacial hydrology and dynamic features of the north-central Greenland ice sheet originated in tectonic events that pre-date the onset of glaciation in Greenland by many tens of millions of years.

    http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2689.html

  4. pochas94 says:

    Is this the ice stream you’re talking about?

    “A glacier between mountains on Greenland’s Geikie Peninsula. The mountains on the Geikie Peninsula in Greenland consist mostly of flood basalts formed during the opening of the North Atlantic Ocean millions of years ago. Credit: NASA / Michael Studinger”

  5. Paul Vaughan says:

    Everyone please keep an eye out for a Bill Illis comment on this and link to it if you see it somewhere.

    My guess is that they are very seriously misinterpreting and that what they have found indicates surface conditions in the deep south (in years preceding).

    If they’re trying to suggest that North Atlantic bottom water was driving North Atlantic surface climate then someone please point to their imaginative explanation of how they think that worked and I’ll brace myself to cringe while I read it.

    The author’s appear completely ignorant of Jose Rial’s main point (about phasing). It looks like they’re confusing phasing with driving.

    All won’t be lost. The new proxy is there. And the idea that oldschool notions about freshwater affecting deep water is wrong isn’t surprising. Probably just reinterpretation is needed (after strategically gathering more background knowledge). It’s totally doable.

  6. Paul Vaughan says:

    As for the Greenland geothermal anomaly (mentioned above by ren & on Suggestions-17 by OB), the more interesting thing there is how does it vary at multidecadal timescale? Without knowing that, its existence has no bearing whatsoever on our interpretation of records for the past 150 years.

    It’s interesting that it exists and it’s really annoying that we didn’t know about it a whole lot sooner, but still we need to know how it varies at multidecadal-centennial timescale.

    So far as I could see, the article’s behind a paywall and that’s not helpful. They’re just obstructing the pursuit of deeper knowledge with such obstacles. Imagine the cumulative impacts of such delays. It’s conceivable that as a result we won’t be ready for something important when we need to be.

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