Antarctic Ice Discussion

[Gray-Wolf]

I wonder just how many 'extensions' to the NASA study ( ending in 2008) on ice gain we are treated too before Paris???

 

I'm either an old cynic or we might just find how disastrous the years since 08' have proven to West Antarctica ( and Greenland?)?? 

[knocker]

Some comments and links here might be of interest GW.

 

http://scienceblogs.com/stoat/2015/11/02/mass-gains-of-the-antarctic-ice-sheet-exceed-losses/

[knocker]

Q&A: Is Antarctica gaining or losing ice?
A new study from scientists at NASA has whipped up a storm in the media by claiming that gains in East Antarctica ice have been outweighing losses in the West Antarctic and the Antarctic Peninsula. Carbon Brief's Q&A sets the study in the context of more recent satellite data, which shows Antarctica is losing ice overall.

[knocker]

West Antarctic coastal snow accumulation rose 30 percent during 20th century, new study finds

 

WASHINGTON, DC — Annual snow accumulation on West Antarctica’s coastal ice sheet increased dramatically during the 20^th century, according to a new study published in the American Geophysical Union journal Geophysical Research Letters.

 

The research gives scientists new insight into Antarctica’s blanket of ice. Understanding how the ice sheet grows and shrinks over time enhances scientists’ understanding of the processes that impact global sea levels, according to the study’s authors.

 

http://news.agu.org/press-release/west-antarctic-coastal-snow-accumulation-rose-30-percent-during-20th-century-new-study-finds/

 

And

 

Possible that winds driving West Antarctic melt are in part radiative forcing.

http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-15-0091.1 â€¦

 

Eric Steig

cf our work: https://www.sciencemag.org/content/343/6167/174.abstract â€¦

Edited November 4, 2015 by knocker

[knocker]

So what is really happening in Antarctica?

 

Filed under:10 November 2015

 

The recent paper by Zwally et al. in the Journal of Glaciology has been widely reported as evidence that Antarctic is gaining mass, and hence lowering sea level. Is it? Expert Jonathan Bamber weighs in.

 

- See more at: http://www.realclimate.org/index.php/archives/2015/11/so-what-is-really-happening-in-antarctica/#sthash.RzSrewzh.dpuf

Edited November 10, 2015 by knocker

[knocker]

Potential sea-level rise from Antarctic ice-sheet instability constrained by observations

 

Large parts of the Antarctic ice sheet lying on bedrock below sea level may be vulnerable to marine-ice-sheet instability (MISI)¹, a self-sustaining retreat of the grounding line triggered by oceanic or atmospheric changes. There is growing evidence^{2, 3, 4} that MISI may be underway throughout the Amundsen Sea embayment (ASE), which contains ice equivalent to more than a metre of global sea-level rise. If triggered in other regions^{5, 6, 7, 8}, the centennial to millennial contribution could be several metres. Physically plausible projections are challenging⁹: numerical models with sufficient spatial resolution to simulate grounding-line processes have been too computationally expensive^{2, 3, 10} to generate large ensembles for uncertainty assessment, and lower-resolution model projections¹¹ rely on parameterizations that are only loosely constrained by present day changes. Here we project that the Antarctic ice sheet will contribute up to 30 cm sea-level equivalent by 2100 and 72 cm by 2200 (95% quantiles) where the ASE dominates. Our process-based, statistical approach gives skewed and complex probability distributions (single mode, 10 cm, at 2100; two modes, 49 cm and 6 cm, at 2200). The dependence of sliding on basal friction is a key unknown: nonlinear relationships favour higher contributions. Results are conditional on assessments of MISI risk on the basis of projected triggers under the climate scenario A1B (ref. 9), although sensitivity to these is limited by theoretical and topographical constraints on the rate and extent of ice loss. We find that contributions are restricted by a combination of these constraints, calibration with success in simulating observed ASE losses, and low assessed risk in some basins. Our assessment suggests that upper-bound estimates from low-resolution models and physical arguments⁹ (up to a metre by 2100 and around one and a half by 2200) are implausible under current understanding of physical mechanisms and potential triggers.

 

http://www.nature.com/nature/journal/vaop/ncurrent/full/nature16147.html

 

Discussion

 

https://www.bas.ac.uk/media-post/news-story-sea-level-rise-from-antarctic-collapse/

[knocker]

Further to the above

 

Antarctic Ice Sheet Deterioration Study Left Out Important Factors

 

 

A few days ago a team of climate scientists (Catherine Ritz, Tamsin Edwards, Gaël Durand, Antony Payne, Vincent Peyaud, and Richard Hindmarsh) published a study of “Potential sea-level rise from Antarctic ice-sheet instability constrained by observations.â€

 

The study asked how much Antarctic ice sheets might contribute to global sea level by 2100 and 2200 AD. The results contradicted some earlier estimates which are on the high end, but conformed very closely to the current IPCC estimate, raising that number by a negligible amount.

 

The authors note that rising seas due to global warming is a significant problem. In other words, this research could be good news on one way, in that the highest estimates were not supported. But it is bad news in another way, in that the Antarctic ice sheet will contribute enough that when added to other sources of sea level rise, coastal regions will be seriously affected.

 

One of the study’s authors, Tamsin Edwards, wrote a summary of the paper in The Guardian. That essay provides a useful summary of the history of Antarctic ice-sheet research, and places the new research in perspective. In particular, Edwards notes,

 

Edited November 23, 2015 by knocker

[stewfox]

As we enter into December the Antarctica sea ice is STILL 5,000,000 above the Arctic

 

https://ads.nipr.ac.jp/vishop/vishop-extent.html?S

 

https://ads.nipr.ac.jp/vishop/vishop-extent.html?N

 

Would be lovely to have a full set of reporting stations in the Southern Hemisphere

Edited November 25, 2015 by stewfox

[Methuselah]

What is the 'Artic'?

[stewfox]

What is the 'Artic'?

 

Its the Arctic see attached for definition 

 

https://en.wikipedia.org/wiki/Arctic

 

 

Further info here

 

https://forum.netweather.tv/topic/84034-arctic-sea-ice-discussion-2015-2016-the-refreeze/

[knocker]

How increasing CO₂ leads to an increased negative greenhouse effect in Antarctica

 

CO₂ is the strongest anthropogenic forcing agent for climate change since pre-industrial times. Like other greenhouse gases, CO₂ absorbs terrestrial surface radiation and causes emission from the atmosphere to space. As the surface is generally warmer than the atmosphere, the total long-wave emission to space is commonly less than the surface emission. However, this does not hold true for the high elevated areas of central Antarctica. For this region, the emission to space is higher than the surface emission; and the greenhouse effect of CO₂ is around zero or even negative, which has not been discussed so far. We investigated this in detail and show that for central Antarctica an increase in CO₂ concentration leads to an increased long-wave energy loss to space, which cools the Earth-atmosphere system. These findings for central Antarctica are in contrast to the general warming effect of increasing CO₂.

 

http://onlinelibrary.wiley.com/doi/10.1002/2015GL066749/abstract

[knocker]

Geophysicist Questions Stability of Antarctic Ice Sheet


Quote

A professor in the College of Arts and Sciences is joining the growing debate over the fate of the world’s largest ice sheet, whose sudden melting is sending shockwaves throughout the geophysics community.

http://news.syr.edu/geophysicist-questions-stability-of-antarctic-ice-sheet
-35922/

[knocker]

Warming ocean water undercuts Antarctic ice shelves -

Quote

This is a joint release of the National Snow and Ice Data Center, CIRES, the University of Colorado Boulder and Scripps Institution of Oceanography.

“Upside-down rivers” of warm ocean water threaten the stability of floating ice shelves in Antarctica, according to a new study led by researchers at the University of Colorado Boulder’s National Snow and Ice Data Center. The study highlights how parts of Antarctica’s ice sheet may be weakening due to contact with warm ocean water.

“We found that warm ocean water is carving these 'upside-down rivers,’ or basal channels, into the undersides of ice shelves all around the Antarctic continent. In at least some cases these channels weaken the ice shelves, making them more vulnerable to disintegration,” said Karen Alley, a Ph.D. student in CU-Boulder’s Department of Geological Sciences and lead author of an analysis published today in Nature Geoscience.

- See more at: http://www.colorado.edu/news/releases/2016/03/14/warming-ocean-water-undercuts-antarctic-ice-shelves#sthash.lvtaNt1k.dpuf

 

[knocker]

 

[stewfox]

On ‎23‎/‎03‎/‎2016 at 8:41 PM, knocker said:

On ‎23‎/‎03‎/‎2016 at 8:41 PM, knocker said:

 

 

If you start with 'Antarctica is warming' ....   Cleary that is not a given. The attached suggest some warming but in many areas not significant.

-----------------

https://en.wikipedia.org/wiki/Antarctica_cooling_controversy

As presented in page 193 of the novel : "The data show that one relatively small area called the Antarctic Peninsula is melting and calving huge icebergs. That's what gets reported year after year. But the continent as a whole is getting colder, and the ice is getting thicker".[12] Crichton's footnote source is Doran et al., 20

-----------------------

You will end up with 'we don't know' re why Antarctica ice is increasing

 

Mean while Antarctica sea ice above the long term average with a recent surge as they head towards Autumn.

 

https://ads.nipr.ac.jp/vishop/vishop-extent.html?S

Cant remove the double post above

 

 

Edited March 27, 2016 by stewfox

[BornFromTheVoid]

3 hours ago, stewfox said:

If you start with 'Antarctica is warming' ....   Cleary that is not a given. The attached suggest some warming but in many areas not significant.

-----------------

https://en.wikipedia.org/wiki/Antarctica_cooling_controversy

As presented in page 193 of the novel : "The data show that one relatively small area called the Antarctic Peninsula is melting and calving huge icebergs. That's what gets reported year after year. But the continent as a whole is getting colder, and the ice is getting thicker".[12] Crichton's footnote source is Doran et al., 20

-----------------------

You will end up with 'we don't know' re why Antarctica ice is increasing

 

Mean while Antarctica sea ice above the long term average with a recent surge as they head towards Autumn.

 

https://ads.nipr.ac.jp/vishop/vishop-extent.html?S

Cant remove the double post above

 

 

 

The pertinent part of the wikipedia page.

"there is no evidence of a corresponding controversy in the scientific community"

[Gray-Wolf]

In the 2012 Arctic we saw the 'ice factory set up over Bering and the ice extent bloom to max proportions prior to maximum. Then what happen to 2012 in the Arctic?

So , with the Ozone hole driven Katabatic winds surging out over the icy waters around Antarctica is it really so surprising that the 'mother of all ice factories' was able to produce a stretched winter sea ice pack?

You see, in a warming world, once the ice shelfs are gone there is nothing to stop gravity slumping that, over a mile thick pile of ice, into the Southern Oceans.

So the trick , I imagine. is not to ponder seasonal ice but to keep and eye on the 'gates' that keep us from a deluge of ice melt and sea level rise.

So , how are the ice shelfs ( including the Mother of them all at Ross) doing over the past two decades?

[knocker]

An interesting article (as always) by Dr. Ricky Rood.

No Way to Slow Down: Silence Howling in Antarctica

Quote

Eight years later, I am satisfied that that was a good list. Also, I am shocked that it has been eight years, but that’s a more existential issue. Going into the Conference of the Parties in Paris, I felt that one of the most defining new science-based results was the evidence of loss of some of the West Antarctic Glaciers. (A brief mention in my September 2014 blog) Loss, here, means that we have reached a point where these glaciers will continue to melt, and there is no identified physical mechanism that will stop this melting.

https://www.wunderground.com/blog/RickyRood/no-way-to-slow-down-silence-howling-in-antarctica

[stewfox]

12 hours ago, knocker said:

An interesting article (as always) by Dr. Ricky Rood.

No Way to Slow Down: Silence Howling in Antarctica

https://www.wunderground.com/blog/RickyRood/no-way-to-slow-down-silence-howling-in-antarctica

Its a bucket list of what could happen from an alarmist nothing really new in it ? e.g

""""In this paper Hansen et al. conclude that we can see “nonlinearly growing sea level rise, reaching several meters over a timescale of 50–150 years"""

 

Meanwhile Antarctic sea ice extent remains above the averages of 1980s, 1990s , 2000s but its early days

https://ads.nipr.ac.jp/vishop/vishop-extent.html?S

[knocker]

 

[knocker]

 

[Gray-Wolf]

https://data1.geo.tu-dresden.de/ais_gmb/

A nice way to look at mass gains/losses over the past decade and a bit! Take interest in the West Antarctic Basins and what is occurring there!!!

[knocker]

More Trouble at Totten Glacier

https://climatecrocks.com/2016/05/19/more-trouble-at-totten-glacier-2/

[knocker]

Will more snow over Antarctica offset rising seas? Don’t count on it

Quote

Many factors related to warming will conspire to raise the planet’s oceans over coming decades — thermal expansion of the world’s oceans, melting of snow and ice worldwide, and the collapse of massive ice sheets.

But there are a few potential brakes. One was supposed to be heavier snowfall over the vast continent of Antarctica. Warmer air will hold more moisture and thus generate more snow to fall inland and slightly rebuild the glacier, according to climate model projections.

Not so fast, says a University of Washington study published in Geophysical Research Letters, a journal of the American Geophysical Union. The authors looked at evidence from the West Antarctic Ice Sheet Divide ice core to get a first clear look at how the continent’s snowfall has varied over 31,000 years.

http://www.washington.edu/news/2016/05/19/will-more-snow-over-antarctica-offset-rising-seas-dont-count-on-it/

[knocker]

Deep, old water explains why Antarctic Ocean hasn't warmed

Quote

The waters surrounding Antarctica may be one of the last places to experience human-driven climate change. New research from the University of Washington and the Massachusetts Institute of Technology finds that ocean currents explain why the seawater has stayed at roughly the same temperature while most of the rest of the planet has warmed.

The study resolves a scientific conundrum, and an inconsistent pattern of warming often seized on by climate deniers. Observations and climate models show that the unique currents around Antarctica continually pull deep, centuries-old water up to the surface - seawater that last touched Earth's atmosphere before the machine age, and has never experienced fossil fuel-related climate change. The paper is published May 30 in Nature Geoscience.

Read more at: http://phys.org/news/2016-05-deep-antarctic-ocean-hasnt.html#jCp