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Paleo Study: CO2 Risk To Antarctica Worse Than Thought

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  Paleo Study: CO2 Risk To Antarctica Worse Than Thought Sam Wormley <swormley1@gmail.com> - 2016-02-26 16:33 -0600
    Re: Paleo Study: CO2 Risk To Antarctica Worse Than Thought jimp@specsol.spam.sux.com - 2016-02-26 22:52 +0000
      Re: Paleo Study: CO2 Risk To Antarctica Worse Than Thought Wally W. <ww84wa@aim.com> - 2016-02-27 13:49 -0500

#557043 — Paleo Study: CO2 Risk To Antarctica Worse Than Thought

Paleo Study: CO2 Risk To Antarctica Worse Than Thought
> http://www.reportingclimatescience.com/news-stories/article/paleo-study-co2-risk-to-antarctica-worse-than-thought.html


> Atmospheric carbon dioxide concentrations 16 million years ago were
> similar to those seen today but temperatures were warmer and ocean
> levels were much higher. Two new studies of conditions in Antarctica
> at that time using data from the ANDRILL project suggest that today's
> Antarctic ice sheets could be more vulnerable to carbon dioxide than
> thought

> Abstracts
>
> Antarctic ice sheet sensitivity to atmospheric CO2 variations in the
> early to mid-Miocene
>
> Geological records from the Antarctic margin offer direct evidence of
> environmental variability at high southern latitudes and provide
> insight regarding ice sheet sensitivity to past climate change. The
> early to mid-Miocene (23–14 Mya) is a compelling interval to study as
> global temperatures and atmospheric CO2 concentrations were similar
> to those projected for coming centuries. Importantly, this time
> interval includes the Miocene Climatic Optimum, a period of global
> warmth during which average surface temperatures were 3–4 °C higher
> than today. Miocene sediments in the ANDRILL-2A drill core from the
> Western Ross Sea, Antarctica, indicate that the Antarctic ice sheet
> (AIS) was highly variable through this key time interval. A
> multiproxy dataset derived from the core identifies four distinct
> environmental motifs based on changes in sedimentary facies, fossil
> assemblages, geochemistry, and paleotemperature. Four major
> disconformities in the drill core coincide with regional seismic
> discontinuities and reflect transient expansion of grounded ice
> across the Ross Sea. They correlate with major positive shifts in
> benthic oxygen isotope records and generally coincide with intervals
> when atmospheric CO2 concentrations were at or below preindustrial
> levels (∼280 ppm). Five intervals reflect ice sheet minima and air
> temperatures warm enough for substantial ice mass loss during
> episodes of high (∼500 ppm) atmospheric CO2. These new drill core
> data and associated ice sheet modeling experiments indicate that
> polar climate and the AIS were highly sensitive to relatively small
> changes in atmospheric CO2 during the early to mid-Miocene.
>
> Dynamic Antarctic ice sheet during the early to mid-Miocene
>
> Geological data indicate that there were major variations in
> Antarctic ice sheet volume and extent during the early to
> mid-Miocene. Simulating such large-scale changes is problematic
> because of a strong hysteresis effect, which results in stability
> once the ice sheets have reached continental size. A relatively
> narrow range of atmospheric CO2 concentrations indicated by proxy
> records exacerbates this problem. Here, we are able to simulate
> large-scale variability of the early to mid-Miocene Antarctic ice
> sheet because of three developments in our modeling approach. (i) We
> use a climate–ice sheet coupling method utilizing a high-resolution
> atmospheric component to account for ice sheet–climate feedbacks.
> (ii) The ice sheet model includes recently proposed mechanisms for
> retreat into deep subglacial basins caused by ice-cliff failure and
> ice-shelf hydrofracture. (iii) We account for changes in the oxygen
> isotopic composition of the ice sheet by using isotope-enabled
> climate and ice sheet models. We compare our modeling results with
> ice-proximal records emerging from a sedimentological drill core from
> the Ross Sea (Andrill-2A) that is presented in a companion article.
> The variability in Antarctic ice volume that we simulate is
> equivalent to a seawater oxygen isotope signal of 0.52–0.66‰, or a
> sea level equivalent change of 30–36 m, for a range of atmospheric
> CO2 between 280 and 500 ppm and a changing astronomical
> configuration. This result represents a substantial advance in
> resolving the long-standing model data conflict of Miocene Antarctic
> ice sheet and sea level variability.
>
> Citations
>
> Antarctic ice sheet sensitivity to atmospheric CO2 variations in the
> early to mid-Miocene by Richard Levy, David Harwood, Fabio Florindo,
> Francesca Sangiorgi, Robert Tripati, Hilmar von Eynatten, Edward
> Gasson, Gerhard Kuhn, Aradhna Tripati, Robert DeConto, Christopher
> Fielding, Brad Field, Nicholas Golledge, Robert McKay, Timothy Naish,
> Matthew Olney, David Pollard, Stefan Schouten, Franco Talarico,
> Sophie Warny, Veronica Willmott, Gary Acton, Kurt Panter, Timothy
> Paulsen, Marco Taviani and the SMS Science Team published in the
> Proceedings of the National Academy of Sciences, doi:
> 10.1073/pnas.1516030113




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#557052

Sam Wormley <swormley1@gmail.com> wrote:
> Paleo Study: CO2 Risk To Antarctica Worse Than Thought

Copy this crap to someplace it might be appropriate.


-- 
Jim Pennino

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#557288

On Fri, 26 Feb 2016 22:52:40 -0000, jimp@specsol.spam.sux.com wrote:

>Sam Wormley <swormley1@gmail.com> wrote:
>> Paleo Study: CO2 Risk To Antarctica Worse Than Thought
>
>Copy this crap to someplace it might be appropriate.

... to his blog.

He should start one ... 

"The Shiny Things Sam Found Today"

... and count the visitors.

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