Via a Euerekalert press release
Past climate of the northern Antarctic Peninsular informs global warming debate
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  IMAGE: The American icebreaker RV/IB Nathanial B. Palmer is shown off the South Shetland Islands. The drilling rig is clearly seen on the rear deck.Click here for more information. |
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The seriousness of current global warming is underlined by a reconstruction of climate at Maxwell Bay in the South Shetland Islands of the Antarctic Peninsula over approximately the last 14,000 years, which appears to show that the current warming and widespread loss of glacial ice are unprecedented.
“At no time during the last 14 thousand years was there a period of climate warming and loss of ice as large and regionally synchronous as that we are now witnessing in the Antarctic Peninsula,” says team member Dr Steve Bohaty of the National Oceanography Centre, Southampton (NOCS), home of the University of Southampton’s School of Ocean and Earth Science (SOES).”
The findings are based on a detailed analysis of the thickest Holocene sediment core yet drilled in the Antarctic Peninsula. “By studying the climate history of the past and identifying causes of these changes, we are better placed to evaluate current climate change and its impacts in the Antarctic,” says Dr Bohaty.
As part of a 2005 research cruise aboard the American icebreaker RV/IB Nathanial B. Palmer, the scientists drilled down through the sediments at Maxwell Bay, a fjord at the northwest tip of the Antarctic Peninsula. They drilled down as far as the bedrock, obtaining a nearly complete 108.3-metre sediment core.
Back in the lab, they performed a battery of detailed sedimentological and geochemical analyses on the core. Radiocarbon dating showed that the oldest sediments at the bottom of the core were deposited between 14.1 and 14.8 thousand years ago, and sedimentation rates at the site varied from 0.7 to around 30 milimetres a year through the Holocene; that is, the geological period that began around 11,700 years ago, continuing to the present.
They conclude that ice was grounded in the fjord during the Last Glacial Maximum – the height of the last ice age – and eroded older sediments from the fjord. Later, the grounded ice retreated, leaving a permanent floating ice canopy.
The evidence points to a period of rapid glacial retreat from 10.1 to 8.2 thousand years ago, followed by a period of reduced sea-ice cover and warm water conditions occurring between 8.2 and 5.9 thousand years ago. An important finding of the study is that the mid-Holocene warming interval does not appear to have occurred synchronously throughout the region, and its timing and duration was most likely influenced at different sites by local oceanographic controls, as well as physical geography.
Following the mid-Holocene warming interval, the climate gradually cooled over the next three thousand years or so, resulting in more extensive sea-ice cover in the bay. But the researchers find no evidence that the ice advanced in Maxwell Bay during the so-called Little Ice Age in the sixteenth to mid-nineteenth century.
The Antarctic Peninsula area has warmed 3 °C in the past five decades, with increased rainfall and a widespread retreat of glaciers. “Atmospheric warming trends linked to global climate change are an obvious culprit for the observed regional climate changes,” say the researchers.
The study was supported by the US National Science Foundation Office of Polar Programs.
The authors are: K. T. Milliken and J. B. Anderson (Rice University), J.S. Wellner (University of Houston), S.M. Bohaty (NOCS/SOES) and P.L. Manley (Middlebury College, Vermont).
Publication:
Milliken, K. T., et al. High-resolution Holocene climate record from Maxwell Bay, South Shetland Islands, Antarctica. Geological Society of America Bulletin 121, 1711-1725 (2009).
http://gsabulletin.gsapubs.org/content/121/11-12/1711
If my deep freeze had been operating at minus 20 deg C fifty years ago, and now was working at minus 17C, and I noted the ice was starting to melt, I do not believe I would declare that as being the reason. You see, I know the melting temperature of ice. In fact, if it emerged during my study of the situation that I had observed that my downstairs neighbour had, since way back, had a great fire burning immediately under the concrete slab on which my deep freeze stands, I might scratch my head and wonder aloud: “Could that possibly have anything to do with this most irritating melting phenomenon?”
Geoff Alder
Antarctic sea ice is increasing, East Antarctica ice sheet is increasing, West Antarctica sheet is decreasing. By cherry-picking indicators, you may “prove” almost whatever you like, but here is, at least, a fairly recent assessment:
Citation: Velicogna, I. (2009), Increasing rates of ice mass loss from the Greenland and Antarctic ice sheets revealed by GRACE, Geophys. Res. Lett., 36, L19503, doi:10.1029/2009GL040222.
Received 28 July 2009; accepted 3 September 2009; published 13 October 2009.
“We use monthly measurements of time-variable gravity from the GRACE (Gravity Recovery and Climate Experiment) satellite gravity mission to determine the ice mass-loss for the Greenland and Antarctic Ice Sheets during the period between April 2002 and February 2009. We find that during this time period the mass loss of the ice sheets is not a constant, but accelerating with time, i.e., that the GRACE observations are better represented by a quadratic trend than by a linear one, implying that the ice sheets contribution to sea level becomes larger with time. In Greenland, the mass loss increased from 137 Gt/yr in 2002–2003 to 286 Gt/yr in 2007–2009, i.e., an acceleration of −30 ± 11 Gt/yr2 in 2002–2009. In Antarctica the mass loss increased from 104 Gt/yr in 2002–2006 to 246 Gt/yr in 2006–2009, i.e., an acceleration of −26 ± 14 Gt/yr2 in 2002–2009. The observed acceleration in ice sheet mass loss helps reconcile GRACE ice mass estimates obtained for different time periods.”
No matter what day of the year you pick, there is always a place on Planet Earth that is very warm, and a place that is very cold. Why would Antarctica be any different? It’s still a frozen wasteland, uninhabitable, and it makes no difference whether one place there is 2 degrees warmer than the rest of it anomalously. You still can’t live there. And it makes no difference whether you freeze to death at -40 or -100, you’re still a goner.
Maybe in 10 million years hence, when Antarctica had drifted somewhat away from the South Pole, things could be different. The place is so far gone in deep cold that not even 10,000 years of Al Gore’s firey sermons is going to make it livable. The place is dead. Only buried volcanoes and ice live in it’s desolate interior.
Doesn’t look like the place is melting to me:
http://arctic.atmos.uiuc.edu/cryosphere/NEWIMAGES/antarctic.seaice.color.000.png
And speaking of the polar opposite:
http://arctic.atmos.uiuc.edu/cryosphere/NEWIMAGES/arctic.seaice.color.000.png
Who wants to write the new book “Late Interglacials for Dummies”?
Just to avoid assertions that the work cited has been “refuted”:
“Our work suggests that while West Antarctica is still losing significant amounts of ice, the loss appears to be slightly slower than some recent estimates,” said Ian Dalziel, lead principal investigator for WAGN. “So the take home message is that Antarctica is contributing to rising sea levels. It is the rate that is unclear.”
Geodetic measurements of vertical crustal velocity in West Antarctica and the implications for ice mass balance
Received 20 May 2009; accepted 28 August 2009; published 13 October 2009.
Citation: Bevis, M., et al. (2009), Geodetic measurements of vertical crustal velocity in West Antarctica and the implications for ice mass balance, Geochem. Geophys. Geosyst., 10, Q10005, doi:10.1029/2009GC002642.
“We present preliminary geodetic estimates for vertical bedrock velocity at twelve survey GPS stations in the West Antarctic GPS Network, an additional survey station in the northern Antarctic Peninsula, and eleven continuous GPS stations distributed across the continent. The spatial pattern of these velocities is not consistent with any postglacial rebound (PGR) model known to us. Four leading PGR models appear to be overpredicting uplift rates in the Transantarctic Mountains and West Antarctica and underpredicting them in the peninsula north of 65°. This discrepancy cannot be explained in terms of an elastic response to modern ice loss (except, perhaps, in part of the peninsula). Therefore, our initial geodetic results suggest that most GRACE ice mass rate estimates, which are critically dependent on a PGR correction, are systematically biased and are overpredicting ice loss for the continent as a whole.”
And, observational periods of less than 10 years is of course too little to reach any firm conclusions.
Let me be perfectly clear:
When the ice block melts we see floating, it will displace no more water.
When you compare it to the largest ice bergs from the Antarctic that is a trivial sliver of ice, and of absolutely no consequence.
The largest ice berg ever observed (there may have been much larger in the past but we simply have no reports) in the Antarctic was observed in 1955 by the U.S.S. Glacier, 150 miles west of Scott Island inside the Antarctic Circle. It measured 60 miles wide by 208 miles long, or about 12,000 square miles (31,000 square kilometers).
The B-15 ice berg that calved from Antarctic’s Ross Ice Shelf around March 20, 2000, measured 183 miles long (295 kilometers) and about 25 miles wide (37 kilometers). It extended about 900 feet below the surface and rises about 120 feet (30 meters) above the ocean.
If the media put these sort of events into historical perspective two things would happen. First they would realize it was a non-event and not bother to report it, and if they did need to use it as a filler article, the readers would have a clue that an antarctic ice berg of that size is not all that interesting, except for the locals who have not seen one of the large slab icebergs before.
Larry
Here is a link about the large ice bergs, and mentions that these large slab icebergs such as B-15 are a normal part of the shelf ice.
http://ecology.com/featuresarchive/largesticeberg/
Larry
Noelene (18:01:15) :
Sorry for the second post,but I found a photo
http://www.themercury.com.au/article/2009/11/07/108371_tasmania-news.html
Wow! The visible part of the iceberg is a rectangular prism. Can anybody explain how that happens?
Jeff Id (20:06:32) “It never ends. It really is worse than we thought.”
Perhaps it is unwise to underestimate the resilience of determined religion?
30 years from now new disciples, guided by old “sages” who kept the myths alive, will be “rediscovering” the “classics” [from the era when checks & balances were conveniently out-of-order].
This could be a war of attrition that drags on for generations. I hope powerful key players are planning the investments properly, rather than foolishly thinking this battle will blow-over in a favorable manner by some fluke without the need for strategic investment in troops, equipment, & information. It is time for less mouthing and more investment if the resistance is to become more intently serious about succeeding. Support our troops [with more than lip service].
And so we hear from another ‘Cherry Plucker’ even after Yamal was such a dissapointment. Maintaining altitude is difficult when your on the back side of the power curve. My condolences.
“UNPRECEDENTED” NONSENSE
Go here and scroll down to the section “Earth’s Icehouse History.”
http://www.geocraft.com/WVFossils/global_warming.html
Note the gif of the last 18,000 years of glacier loss in North America.
14,000 years ago, Canada was a solid block of ice. And these clowns want us to believe that when an icecube melts today, it’s unprecedented?! It may be premature to say that science is dead, but it’s far from healthy.
yonason (22:36:28) “It may be premature to say that science is dead, but it’s far from healthy.”
The system has been corrupted by the “shortage” of funding.
I put “shortage” in quotes because in my experience most of the money goes to fat union wages for unproductive university employees. For every one person who has a job at a university, there could easily be 3 if we did not tolerate such outrageous waste (which is rapidly destroying our society). It’s ridiculous – you get people making $25/hour or more to do tasks that you could easily get people to do for $10/hour.
If careful planning starts now, it will take 4 decades or more to fix the system …and a lot can happen in 40 years that might complicate things further.
Clarification: I’m not calling for radical change. Radical change leads to instability.
I am now an AGWer. I just found out that if the Arctic melts, the blob will come back to get us. Steve McQueen said so in 1958!
Paul Vaughan (01:28:42) :
“Radical change leads to instability.”
And that’s the biggest problem with the AGW crowd, they want radical change. They think that they will profit from it, but the golden goose is the free market, and when it’s dead, all their fantasies will come crumbling down around them, and us.
yonason (15:27:17) “And that’s the biggest problem with the AGW crowd, they want radical change.”
Agreed. Radical change is the single biggest threat to nature.
Sensible minds advocating balance will prevail.
Didn’t they drop it in the Antarctic?