Loss of big Antarctic glaciers inevitable

[Carrikature]

No I am not. Arctic sea ice has increased since 2007, regardless of Tiggy's stupid graph gif. If the planet is truly warming like he says it is, then it should not be able to recover 50% of its lost volume over that time. It should continue to lose ice like it did in the Holocene. Antarctic sea ice has increased over the past 60 years, which again should not be possible if temperatures are rising at "an alarming rate".

Bill, you made a claim and presented a link to support it. The link does not support it, and I showed as much. In response, you basically said, "yeah but what about...". That's moving goalposts.

"Should not be able to recover 50% of its lost volume" is an unsupported assertion. You've followed that up with another assertion of "should not be possible". Nothing you've said, or shown, yet counters the pretty obvious fact that the trend has continued to be downward. Your graph does not counter this, as it's still pretty easy to see that global ice is lower than it was, and has continued to be that way.

[Bill the Cat]

Like I said, there are always clueless morons who don't understand regression towards the mean.

And there are childish hacks like you who parrot cherry picked data and starting points that favor their interpretation. Well, two can play at that game, Tiggy.

Holocene fluctuations in Arctic sea-ice cover: dinocyst-based reconstructions for the eastern Chukchi Sea
J.L. McKay, A. de Vernal, C. Hillaire-Marcel, C. Not, L. Polyak, and D. Darby

Superimposed on these long-term trends are millennial-scale fluctuations characterized by periods of low sea-ice and high sea-surface temperature and salinity
that appear quasi-cyclic with a frequency of about one every 2500–3000 years... More importantly, there have been times when sea-ice cover was less extensive than at the end of the 20th century.

And guess where we are today in that observed quasi-cycle?

[Bill the Cat]

... as it's still pretty easy to see that global ice is lower than it was,

With what starting point? That's the key that Tiggy will never admit. One can skew the results with a shifted starting point. When we look at a broader sampling, it becomes less "easy" to claim that sea ice is lower, and in fact, the study I cited to him states that there were time in the past 9000 years where Arctic sea ice was significantly lower than the last 2 decades. If we use the quasi-cycle's low point as our reference point, then we can say that it is much more extensive.

And with that, I will drop out before I say something to Tiggy that I will regret.

[HMS_Beagle]

And there are childish hacks like you who parrot cherry picked data and starting points that favor their interpretation. Well, two can play at that game, Tiggy.

Holocene fluctuations in Arctic sea-ice cover: dinocyst-based reconstructions for the eastern Chukchi Sea
J.L. McKay, A. de Vernal, C. Hillaire-Marcel, C. Not, L. Polyak, and D. Darby

Superimposed on these long-term trends are millennial-scale fluctuations characterized by periods of low sea-ice and high sea-surface temperature and salinity
that appear quasi-cyclic with a frequency of about one every 2500–3000 years... More importantly, there have been times when sea-ice cover was less extensive than at the end of the 20th century.

And guess where we are today in that observed quasi-cycle?

LOL! Clueless moron C&Ps part of the abstract from a paper he never read and which has zero significance for the overall Arctic ice data of the last 35 years.

Here's the whole paper that you were too lazy / dishonest / clueless to post

Holocene fluctuations in Arctic sea-ice cover: dinocyst-based reconstructions for the eastern Chukchi Sea
McKay et al
Canadian Journal of Earth Sciences, Vol 45, No. 11, 2008, pp. 1377-1397(21)

Abstract: Cores from site HLY0501-05 on the Alaskan margin in the eastern Chukchi Sea were analyzed for their geochemical (organic carbon, δ13Corg, Corg/N, and CaCO3) and palynological (dinocyst, pollen, and spores) content to document oceanographic changes during the Holocene. The chronology of the cores was established from 210Pb dating of near-surface sediments and 14C dating of bivalve shells. The sediments span the last 9000 years, possibly more, but with a gap between the base of the trigger core and top of the piston core. Sedimentation rates are very high (∼156 cm/ka), allowing analyses with a decadal to centennial resolution. The data suggest a shift from a dominantly terrigenous to marine input from the early to late Holocene. Dinocyst assemblages are characterized by relatively high concentrations (600–7200 cysts/cm3) and high species diversity, allowing the use of the modern analogue technique for the reconstruction of sea-ice cover, summer temperature, and salinity. Results indicate a decrease in sea-ice cover and a corresponding, albeit much smaller, increase in summer sea-surface temperature over the past 9000 years. Superimposed on these long-term trends are millennial-scale fluctuations characterized by periods of low sea-ice and high sea-surface temperature and salinity that appear quasi-cyclic with a frequency of about one every 2500–3000 years. The results of this study clearly show that sea-ice cover in the western Arctic Ocean has varied throughout the Holocene. More importantly, there have been times when sea-ice cover was less extensive than at the end of the 20th century.

No one says or thinks sea ice coverage didn't vary in the last 9000 years. You're running from the evidence of rapid Arctic ice decline associated with AGW over the last 35 years. That includes your idiotic claim that Arctic sea ice has recovered 50% of its lost volume since 2007.

You're the same kind of clueless boob who would claim since forest fires have occurred naturally over the last 9000 years that it's impossible for a fire today to be arson.

[HMS_Beagle]

BTW Bill, while you're busy playing at science by C&Ping cherry-picked crap from crank science denier websites you may want to actually read over the stuff you're mindlessly regurgitating.

From the McKay paper you referenced:

Introduction

There is clear evidence that over the last 30 years the Arctic has been experiencing dramatic environmental changes (e.g., Serreze et al. 2000; Comiso and Parkinson 2004). Most notably, there has been a rapid decline in the extent and thickness of sea-ice in summer and more recently in winter as well (e.g., Parkinson et al. 1999; Comiso 2002; Serreze et al. 2003; Rigor and Wallace 2004; Meier et al. 2005; Comiso 2006; Comiso et al. 2008; Stroeve et al. 2008). It has been suggested that if the present trend continues the Arctic could experience ice-free summers within 30 years (Stroeve et al. 2008). There is, however, debate on the relative influence of natural versus anthropogenic forcing on these recent changes. The decline in sea-ice, which began in the late 1970s, occurred contemporaneously with a major shift in Arctic atmospheric and oceanic circulation (Walsh et al. 1996), hence referred to as the Arctic Oscillation (Thompson and Wallace 1998). At this time, there was a weakening of the Arctic High that is situated over the Beaufort Sea and intensification of the Icelandic Low, conditions characteristic of the positive phase of the Arctic Oscillation (+AO). In response, the Beaufort Gyre contracted and the Transpolar Drift shifted away from Siberia to a more central position in the Arctic Ocean. The decline in Arctic sea ice associated with the +AO results primarily from the rapid removal of older, thicker ice from Arctic through Fram Strait and intensified cyclonic atmospheric circulation that brings warm air into Arctic, thus increasing sea-ice melt (Meier et al. 2005). However, sea ice has continued its rapid decline, since the AO returned to a more neutral state in the late 1990s, suggesting that anthropogenic warming of surface air temperatures is playing a role in the loss (Overland and Wang 2005), as now recognized by the Intergovernmental Panel on Climate Change (IPCC 2007).

Even your own paper contradicts your clueless claims.

[klaus54]

With what starting point? That's the key that Tiggy will never admit. One can skew the results with a shifted starting point. When we look at a broader sampling, it becomes less "easy" to claim that sea ice is lower, and in fact, the study I cited to him states that there were time in the past 9000 years where Arctic sea ice was significantly lower than the last 2 decades. If we use the quasi-cycle's low point as our reference point, then we can say that it is much more extensive.

And with that, I will drop out before I say something to Tiggy that I will regret.

I guess you mean the Holocene climatic optimum?

K54

http://en.wikipedia.org/wiki/Holocene_climatic_optimum

[klaus54]

The big news from yesterday seems worth a comment. Two takes, one an overview, one with some more technical details:
http://www.nature.com/news/key-west-...ppably-1.15202
http://arstechnica.com/science/2014/...l-but-certain/

The gist:
In Western Antarctica, there's a big pile of ice that sits in a basin that's below sea level. If ocean waters invade that basin, then the entire thing is likely to disintegrate. Based on the amount of ice that's currently above sea level, the total rise in ocean levels could be between 2-4 meters.

Right now, a handful of glaciers block the ocean from getting into the basin. The new results describe how those glaciers are decaying, some retreating by nearly a kilometer a year, and with very few features like hills or ridges for them to latch on to. For the next century or so, they'll probably retreat slowly, but sometime within the next 200 years, their edges will reach the downward slope into the basin, at which point the retreat will become rapid.

Two things are confusing me about the thread title. 1) What are the "big" glaciers in Antarctica, since the continent is nearly entirely covered in glacial ice averaging 1 mile thick (up to 2 miles in places.) 2) What does "loss" mean? Total loss? If so, then we're talking thousands of years.

Both sound quite like over-the-top rhetoric. Descriptions should use unambiguous terms and avoid hyperbole. And the AGW issue sure as h-e-double toothpicks doesn't need more hyperbole.

K54

[TheLurch]

Two things are confusing me about the thread title. 1) What are the "big" glaciers in Antarctica, since the continent is nearly entirely covered in glacial ice averaging 1 mile thick (up to 2 miles in places.) 2) What does "loss" mean? Total loss? If so, then we're talking thousands of years.

Both sound quite like over-the-top rhetoric. Descriptions should use unambiguous terms and avoid hyperbole. And the AGW issue sure as h-e-double toothpicks doesn't need more hyperbole.

You're conflating ice sheets, which are largely stationary and where most of the ice is, with glaciers, which sit around the periphery of the ice sheets and drain them. By most reasonable standards, these glaciers are large. The Wikipedia entry on Thwaites, for example, starts by noting it is "unusually broad".

And yes, loss means total loss. Once they lose their existing grounding line (again, almost certainly not for more than a century), most of them see downward slopes to the basin in the continent's interior. The one exception seems to be Thwaites, which has a couple of ridges further to the interior where it's likely to form new grounding lines.

The Universe is a big place. Sometimes reality is a bit (as you put it) over the top. But if you'd read the linked articles, you'd probably have a sense that I wasn't exaggerating.

[klaus54]

You're conflating ice sheets, which are largely stationary and where most of the ice is, with glaciers, which sit around the periphery of the ice sheets and drain them. By most reasonable standards, these glaciers are large. The Wikipedia entry on Thwaites, for example, starts by noting it is "unusually broad".

And yes, loss means total loss. Once they lose their existing grounding line (again, almost certainly not for more than a century), most of them see downward slopes to the basin in the continent's interior. The one exception seems to be Thwaites, which has a couple of ridges further to the interior where it's likely to form new grounding lines.

The Universe is a big place. Sometimes reality is a bit (as you put it) over the top. But if you'd read the linked articles, you'd probably have a sense that I wasn't exaggerating.

"Ice sheet" is often applied to continental glaciers, which is the geomorphically correct term.

It appears you're referring to "valley glaciers".

And how long is "inevitable"?

K54

[seer]

Ok, here is a question. Where I live in southern New England it was once covered with ice/glaciers about 28,000 years ago. As was most of the northern hemisphere as I understand it. The glaciers have been receding and ice melting ever since. Isn't what's presently happening just a continuation of that long process?

[TheLurch]

"Ice sheet" is often applied to continental glaciers, which is the geomorphically correct term.

It appears you're referring to "valley glaciers".

I'm referring to it using the terms that everyone in the scientific community refers to it by:
http://en.wikipedia.org/wiki/Antarctic_ice_sheet

And how long is "inevitable"?

Depends on the trajectory of the melting. Which in turn depends in large part on the trajectory of the future emissions.

[TheLurch]

Ok, here is a question. Where I live in southern New England it was once covered with ice/glaciers about 28,000 years ago. As was most of the northern hemisphere as I understand it. The glaciers have been receding and ice melting ever since. Isn't what's presently happening just a continuation of that long process?

No. The end of glacial periods is triggered by changes in the details of the Earth's orbit and polar wobble - collectively called orbital forcings. The orbital forcings peaked over 5,000 years ago, and there's been a trend towards cooling since. See the graph at this link:
http://www.realclimate.org/index.php...-the-holocene/

[seer]

No. The end of glacial periods is triggered by changes in the details of the Earth's orbit and polar wobble - collectively called orbital forcings. The orbital forcings peaked over 5,000 years ago, and there's been a trend towards cooling since. See the graph at this link:
http://www.realclimate.org/index.php...-the-holocene/

So the warming in the last 150 years or so is only caused by man? No other natural forces involved?

[sylas]

Ok, here is a question. Where I live in southern New England it was once covered with ice/glaciers about 28,000 years ago. As was most of the northern hemisphere as I understand it. The glaciers have been receding and ice melting ever since. Isn't what's presently happening just a continuation of that long process?

No, it isn't. Not even close.

28,000 years ago is the time to the last glacial maximum; the maximum extent of ice in the last "ice age". The ice age (or glacial) ended about 11,000 years ago, with a sharp rise in temperature and retreat of the large ice caps over North America and Eurasia. Temperatures peaked about 8000 years ago, and have generally been in a very slow decline since then. There has been a sharp upturn in temperatures in the last hundred years, driven by atmospheric changes.

That is, the retreat of the ice caps in New England occurred thousands of years ago, in a geologically short period of dramatic warming, long since finished.

The recently measured strong increased in temperature are not continuous with the retreat of ice at the end of the ice age. Between those two times of rapid temperature increase were thousands of years of slow gradual cooling.

Hence the recent ice retreat really is new. It is also completely out of character for the climate cycles Earth has experienced moving in and out of many ice ages over the last couple of million years; the natural processes at work in the present would normally tend to continue that slow cooling. What's different this time is a dramatic change in the atmosphere driven by human activities.

Cheers -- sylas

[seer]

The recently measured strong increased in temperature are not continuous with the retreat of ice at the end of the ice age. Between those two times of rapid temperature increase were thousands of years of slow gradual cooling.

Hence the recent ice retreat really is new. It is also completely out of character for the climate cycles Earth has experienced moving in and out of many ice ages over the last couple of million years; the natural processes at work in the present would normally tend to continue that slow cooling. What's different this time is a dramatic change in the atmosphere driven by human activities.

Cheers -- sylas

Ok, I'll ask again. Is the warming we have seen in the last 150 years or so only caused by man? No other natural forces involved?