Antarctic Ice Discussion

[knocker]

Antarctic sea ice variability and trends, 1979–2010

Abstract. In sharp contrast to the decreasing sea ice coverage of the Arctic, in the Antarctic the sea ice cover has,

on average, expanded since the late 1970s. More specifically, satellite passive-microwave data for the period November

1978–December 2010 reveal an overall positive trend in ice extents of 17 100 ± 2300 km2 yr−1. Much of the increase,

at 13 700 ± 1500 km2 yr−1, has occurred in the region of the Ross Sea, with lesser contributions from the Weddell Sea and Indian Ocean. One region, that of the Bellingshausen/Amundsen Seas, has (like the Arctic) instead experienced significant sea ice decreases, with an overall ice extent trend of −8200 ± 1200 km2 yr−1. When examined through the annual cycle over the 32-yr period 1979–2010, the Southern Hemisphere sea ice cover as a whole experienced positive ice extent trends in every month, ranging in magnitude from a low of 9100 ± 6300 km2 yr−1 in February to a high of 24 700 ± 10 000 km2 yr−1 in May. The

Ross Sea and Indian Ocean also had positive trends in each month, while the Bellingshausen/Amundsen Seas had negative

trends in each month, and the Weddell Sea and western Pacific Ocean had a mixture of positive and negative trends.

Comparing ice-area results to ice-extent results, in each case the ice-area trend has the same sign as the ice-extent trend,

but the magnitudes of the two trends differ, and in some cases these differences allow inferences about the corresponding

changes in sea ice concentrations. The strong pattern of decreasing ice coverage in the Bellingshausen/Amundsen Seas

region and increasing ice coverage in the Ross Sea region is suggestive of changes in atmospheric circulation. This is a

key topic for future research.

http://www.the-cryosphere.net/6/871/2012/tc-6-871-2012.pdf

[Gray-Wolf]

Hi BFTV! I'd noted a number of storms around the continent and would imagine the outer low concentration ice to be driven out into the southern ocean and melt? It may well also lead to a hike in extent though as the outer ice stretches but stays within the 15% criteria?

I note from KL's post that a portion of the continent has shown a 9cm increase in height? Didn't we have papers 3 or 4 years ago showing multimetre hikes in ice heights a sub surface lakes filled and drained? could this 'blue ice region' be displaying this type of ebb and flow as liquid water below lifts and drops the area of ice?

The number of teams doing radar surveys of the ice/surface below would lead us to believe that such areas of dynamic motion will be recognised as such over the next few years?

As for the 'methane issues' ? I'm afraid it will be the same as the rest of the ice sheets that covered over vegetated land masses. Before we started releasing long buried carbon reserves the carbon cycle had plenty of reserves to bring CO2 levels up to past 'highs' and as the ice responds to a warmer planet this carbon will be released back into the system, sadly it'll find that it's place has already been occupied by ancient buried carbon and so will just raise levels beyond past 'highs'?

[BornFromTheVoid]

Hi BFTV! I'd noted a number of storms around the continent and would imagine the outer low concentration ice to be driven out into the southern ocean and melt? It may well also lead to a hike in extent though as the outer ice stretches but stays within the 15% criteria?

I note from KL's post that a portion of the continent has shown a 9cm increase in height? Didn't we have papers 3 or 4 years ago showing multimetre hikes in ice heights a sub surface lakes filled and drained? could this 'blue ice region' be displaying this type of ebb and flow as liquid water below lifts and drops the area of ice?

The number of teams doing radar surveys of the ice/surface below would lead us to believe that such areas of dynamic motion will be recognised as such over the next few years?

As for the 'methane issues' ? I'm afraid it will be the same as the rest of the ice sheets that covered over vegetated land masses. Before we started releasing long buried carbon reserves the carbon cycle had plenty of reserves to bring CO2 levels up to past 'highs' and as the ice responds to a warmer planet this carbon will be released back into the system, sadly it'll find that it's place has already been occupied by ancient buried carbon and so will just raise levels beyond past 'highs'?

Good evening GW. The blue ice region was dropping in height from 1991 until 2008 also, so there must be something quite big going on there. The lack of snow cover wouldn't suggest precip changes in that location, but perhaps some tectonic movement could be another explanation?

The original piece by the ESA is here http://www.esa.int/e...T6UGY50H_0.html

Towards the end, it is mentioned that the data is preliminary, though I'd say we could trust it, as the validation for cryosat2 would demand some extreme accuracy.

I'd be surprised if we see any more climbs in southern ice, as the summer is quickly approaching for Antarctica. The annual rapid decline back to 2 million km2 will be under-way soon!

I think we'll be waiting a while before the ice sheets shrink back to expose those sedimentary basins, unless the hydrocarbon industry decides it time to start drilling through the ice!

[Gray-Wolf]

Agreed BFTV, just a reminder for those who see no issue in our adding part of the carbon cycle (that should have remained in it's long, deep storage) back into the mix? If CO2 lagged temps in past orbital forced warm ups it was as the ice melted back to allow the short storage carbon back into the system (as it surely must during this long buried carbon forced warm up?) leading to CO2 lagging tempature in the past orbital forced warmups?.

The issues are the easy to release carbon in the permafrosts up north that ,along with our released deep storage carbon, will warm things up nicely to allow the harder stuff (Greenland and Antarctica) to join in the fun?

[Methuselah]

In time, possibly, even more likely perhaps, probably. But, as yet, Antarctic ice-cover still appears to be expanding...

[keithlucky]

Close... but no cigar. Antarctic sea ice area has dropped by nearly 140k, so it looks doubtful that the 2007 record will be broken this year.

Last 5 days

Anomaly............ Area ............ Average....2007 Record

0.8978714.. 15.9813147.. 15.0834436.. 16.2323818

1.0512513.. 16.1204205.. 15.0691690.. 16.2323818

1.1447686.. 16.2041264.. 15.0593576.. 16.2323818

1.1654477.. 16.2217293.. 15.0562811.. 16.2323818

1.0325397.. 16.0858021.. 15.0532627.. 16.2323818

According to NOAA Antarctic ice cover record was broken http://wattsupwithth...sept-22nd-2012/

[BornFromTheVoid]

According to NOAA Antarctic ice cover record was broken http://wattsupwithth...sept-22nd-2012/

I'd been meaning to download that data set, which is the NSIDC set by the way, so I'm sure Watts and others will claim it's inaccurate like they do with the NSIDC's Arctic extent, right!?

Anyway, yep, it's correct. What's odd though, is you have to go back to 78th place to find a day from 2007, and before that year, you find days from 2012,2009,2006,2005,2004, 2000, 1998 and 1980, and that's all still within 370k of the new all time record this year!

EDIT: Record wasn't broken on the 13th, it was the 21st

Edited September 30, 2012 by BornFromTheVoid

[keithlucky]

I'd been meaning to download that data set, which is the NSIDC set by the way, so I'm sure Watts and others will claim it's inaccurate like they do with the NSIDC's Arctic extent, right!?

Anyway, yep, it's correct. Infact, the record extent was broken on the 13th, with a new record added every other day after. What's odd though, is you have to go back to 78th place to find a day from 2007, and before that year, you find days from 2012,2009,2006,2005,2004, 2000, 1998 and 1980, and that's all still within 370k of the new all time record this year!

Thanks i will use NSIDC site instead .

[Gray-Wolf]

Hi Pete! The way I imagine things (Antarctic warm up) is a slow buckling of the splendid isolation that the circumpolars have placed Antarctica in over the past 30yrs followed by a rapid collapse of the wind/currents ability to stop the planetary warmth flooding across the continent?

I think it safe to say we are already seeing the 'buckling' occurring now with upper trop temps now 'normalized' with the rest of the planet (and heading down toward the surface already near reaching the highest peaks there?) with the current undercut by the warm southern ocean via the underwater canyons.

I believe that the Arctic Amplification will introduce further heat forcing to the planet (on top of the AGW forcing) and this extra 'shove' will be enough to overcome the wind/currents around the continent.

Folk have to remember that all the ice shelfs lost have been within the period where AGW forcing has been absent from the continent and so must imagine how a sudden warm up will impact those remaining and over what time scale.

As a personal observation cryospheric science seems to be playing a game of 'catchup' over the timings of AGW impact events and I see no reason why this should not be true of the southern Continent? 20yrs ago the E.A.I.S. was thought to be safe from collapse but recent improvements in our knowledge of the mechanics of past collapses would now make this thinking redundant yet it still seems to be a common misconception across the blog-sphere (for those who seek to deny any danger to mankind from global warming?). Sadly if I am correct (even partly) about the speed at which current warming will flood into Antarctica then the facts will be as visible to all as the Arctic meltdown. Where will those in denial of the changes regroup and focus there distractions then or will they finally concede that they were far to overly optimistic about the changes and impacts now ongoing to our planet?

With their promised 'recovery/rebound' of Arctic ice in disarray a skeptic might think that their next target would obviously be the continent that has suffered worse from human forced climate shift in the hope that those forcings will hold up to the warming the rest of the planet is seeing.

I think that this is a risky endevour for the exact same reasons with no sure knowledge as to how the Ozone hole will react to the scale of the forcings now brought to bare on it?

Will it be the upcoming summer that see's the first major upswing in warming across the coastal regions of Antarctica? who knows?. We do know that there is a lot of warming of the planet occured since we forced Antarctica into it's 'splendid isolation' and that nature will do it's best to 'even out' such marked differences over time.

[pottyprof]

Hi Pete! The way I imagine things (Antarctic warm up) is a slow buckling of the splendid isolation that the circumpolars have placed Antarctica in over the past 30yrs followed by a rapid collapse of the wind/currents ability to stop the planetary warmth flooding across the continent?

etc.

No disrespect Ian but 'my thoughts' and 'my opinion' aren't fact. The fact is the we have the largest extent on record. Maybe it will pan out like you say but at the minute there is no proof to back up what you claim. Diversion tactics won't cover that up.

[Gray-Wolf]

Sorry P.P. but we've just witnessed what the changing globe has done to the Arctic why then , in the long run, will Antarctica not follow suit?

I favour a much faster start to this process (as I did with the Arctic 'warm-up/collapse') but it is a process that is underway and unstoppable? As things stand we have plenty of forcing available for the forseeable future even if all our outputs were stopped tomorrow. During that time we have no full understanding of how the carbon ,currently under ice or in permafrost, will react to the current conditions.

All in all it is surely not an 'if' but a when?

Edited September 30, 2012 by Gray-Wolf

[Methuselah]

Sorry P.P. but we've just witnessed what the changing globe has done to the Arctic why then , in the long run, will Antarctica not follow suit?

I favour a much faster start to this process (as I did with the Arctic 'warm-up/collapse') but it is a process that is underway and unstoppable? As things stand we have plenty of forcing available for the forseeable future even if all our outputs were stopped tomorrow. During that time we have no full understanding of how the carbon ,currently under ice or in permafrost, will react to the current conditions.

All in all it is surely not an 'if' but a when?

It probably is 'not an "if" but a when', Ian; I suspect that you and I are in full-agreement on that one...But, as of now, it ain't happening. So, please, can we keep the speculation to a minimum?

[BornFromTheVoid]

When sceptics spout baseless, fact devoid rants about how unimportant CO2 is and how global warming is a scam, then have their right to express those opinions openly and frequently backed up by a moderator here, I think it only fair that GW should be free to speculate about the possible goings on with Antarctica.

[Methuselah]

When sceptics spout baseless, fact devoid rants about how unimportant CO2 is and how global warming is a scam, then have their right to express those opinions openly and frequently backed up by a moderator here, I think it only fair that GW should be free to speculate about the possible goings on with Antarctica.

Hold on a minute, Sam?

Of course we should be able to speculate; I would never suggest otherwise. But, there need be limits to it, otherwise the entire thread will get bogged-down with speculation (and equally speculative refutations of speculation) until we find ourselves in a absurd situation: where we all lose track of where we are...

All I'm asking, is that we (for the sake of comprehensibility) try to keep speculation to a minimum...

Or...start another thread dedicated to the purpose!

[BornFromTheVoid]

Hold on a minute, Sam?

Of course we should be able to speculate; I would never suggest otherwise. But, there need be limits to it, otherwise the entire thread will get bogged-down with speculation (and equally speculative refutations of speculation) until we find ourselves in a absurd situation: where we all lose track of where we are...

All I'm asking, is that we (for the sake of comprehensibility) try to keep speculation to a minimum...

Or...start another thread dedicated to the purpose!

At a time when many are using the high levels of sea ice as a method to dismiss global warming and the Arctic ice loss I think the speculation is ok? A large proportion of comments in this area is speculation of one kind or another.

Is it the length of GWs posts that are the issue? Or is it the drifting on to the ice sheet and methane aspects that are the problem?

[Methuselah]

So, here we go: a brand-new thread entirely dedicated to speculation: http://forum.netweather.tv/topic/74595-antarctic-ice-where-are-we-heading/

[Gray-Wolf]

Why have the folk posting up the Antarctic ice extent/Area data suddenly stopped now we have seen area plummet by 500k over the past few days?

Surely the mechanism enabling F.Y. ice to be so variable is just as interesting as it's extent/area?

Like the Million losses over a week a couple of years back it really does show us just how fragile such 'extensions' are once the storms sweep in. As it is we look to have a number of systems around the continent so just how much ice will we lose over the coming weeks?

Should ice fall below the average for the time of year will it be a sign of Antarctic ice collapse?

If the southern hemisphere does have a warm spring then I'd imagine it will induce quite a number of storms around the continent and we may well enter this melt season below average?

Edited October 1, 2012 by jethro
Be careful of libel/slander laws.

[pottyprof]

Why have the folk posting up the Antarctic ice extent/Area data suddenly stopped now we have seen area plummet by 500k over the past few days?

It doesn't prove anything Ian. It's a day where it's been reduced by 500k. This thread is usually quiet regardless of the time of year.

[songster]

Yes, but if the 500k decrease doesn't prove anything, neither does the preceding increase and record, surely? What matters is the long-term trend: <i>slightly</i> up, but mainly during the winter, with near-complete seasonal melt-out.

[Gray-Wolf]

Yes, but if the 500k decrease doesn't prove anything, neither does the preceding increase and record, surely? What matters is the long-term trend: <i>slightly</i> up, but mainly during the winter, with near-complete seasonal melt-out.

indeed songster. when i was pointing out the continued volume decreases of the Arctic ice ,post 07', i was cried down because of the extent/area figures being more variable. All this meant , to me ,was thinner ,more fragile ice.

to see the same silliness occurring again make me concerned that folk have gained little understanding from witnessing the current rapid Arctic changes?

i have no problems in accepting what the scientific consensus tells us as to why we see a slow increase in the extent winter ice is making over the past 30 yrs around Antarctica. The important thing is we see all of that ice gone by ice min? Were we seeing increases year round (as we see decreases in Arctic ice year round) then you might be asking questions but the fact of ice min being constant and the explanation scientific observation brings us as to why we see this small increase at ice max has me wondering at the validity of the 'fuss' some would appear to wish to cause?

The bigger picture shows us a warming planet and a damaged Ozone hole that is beginning to heal. To me we should be looking for signs that the warm up of the continent is beginning and not hope-casting for some un-natural cool-down?

[BornFromTheVoid]

An good overview of the summer (Arctic) and winter (Antarctic) sea ice min and max from the NSIDC

Poles apart: A record-breaking summer and winter

The sun has set over the central Arctic Ocean and sea ice extent is now increasing. While much attention has been paid to the record minimum Arctic ice extent set on September 16, 2012, winter sea ice extent in Antarctica has reached a record high. The Antarctic extent increase is an interesting response to changes in circulation patterns in the Southern Hemisphere.

http://nsidc.org/arcticseaicenews/2012/10/poles-apart-a-record-breaking-summer-and-winter/

[knocker]

Antarctic Sea Ice—A Polar Opposite? I've a feeling I've posted this before.

As the world’s ice diminishes in the face of climate change—from the

dramatic decline in Arctic sea ice, to thinning at the margins of both the Greenland

and Antarctic ice sheets, to retreating mountain glaciers the world over—Antarctic

sea ice presents something of a paradox. The trend in total sea ice extent in the

Antarctic has remained steady, or even increased slightly, over the past three decades,

confounding climate model predictions showing moderate to strong declines. This

apparent intransigence masks dramatic regional trends; declines in sea ice in the

Bellingshausen Sea region that rival the high-profile decline in the Arctic have been

matched by opposing increases in the Ross Sea. Much of the explanation lies in the

unique nature of the Antarctic sea ice zone. Its position surrounding the continent

and exposure to the high-energy wind and wave fields of the open Southern Ocean

shape both its properties and its connection to the atmosphere and ocean in ways

very different from the Arctic. Sea ice extent and variability are strongly driven by

large-scale climate variability patterns such as the El Niño-Southern Oscillation and

the Southern Annular Mode. Because many of these patterns have opposing effects in

different regions around the continent, decreases in one region are often accompanied

by similar, opposing increases in another. Yet, the failure of climate models to capture

either the overall or regional behavior also reflects, in part, a poor understanding

of sea ice processes. Considerable insight has been gained into the nature of these

processes over the past several decades through field expeditions aboard icebreakers.

However, much remains to be discovered about the nature of Antarctic sea ice; its

connections with the ocean, atmosphere, and ecosystem; and its complex response to

present and future climate change.

http://www.tos.org/o...25-3_maksym.pdf

Edited October 4, 2012 by knocker

[BornFromTheVoid]

Been keeping an eye on the PIG's "crack", and it would appear there is a lot of warm water upwelling going on, though a few days cloudy conditions make it difficult to say for sure. A combination of melting and upwelling, likely due to Ekman Transpot along the coast, has opened up a lot of water along the coast there.

5 days ago and 2 days ago, signs of compaction further north with rapid melting near the glacier mouth

I know it's likely a relatively ordinary occurrence, but with the enhanced westerlies, extra Ekman transport and upwelling, those glaciers and ice shelves are going to experience quite a bit more bottom melt.

[knocker]

Australia's Antarctic airstrip melts

Australia's airstrip in Antarctica is melting, prompting a scramble to find a new way to supply its research bases on the icy continent.

http://www.telegraph.co.uk/news/worldnews/antarctica/9630314/Australias-Antarctic-airstrip-melts.html

[knocker]

Thinning at Hektoria and Green Glaciers

When a large section of the Larsen B ice shelf crumbled into a melange of floating icebergs and drifted away in 2002, glaciologists suspected they would see even more changes to the ice in the Antarctic Peninsula during the coming years.

The nearby Larsen A ice shelf collapsed in a similar fashion in 1995, and in the aftermath the tributary glaciers that fed that floating platform of ice continued to thin and stretch for years. Rather than stabilizing after the breakup, many of Larsen A’s tributary glaciers actually accelerated their slide toward the Weddell Sea.

There is now little doubt that similar changes have affected Larsen B’s tributary glaciers. Chris Shuman—a University of Maryland at Baltimore County glaciologist based at NASA’s Goddard Space Flight Center—and colleagues at the National Snow and Ice Data Center and the University of Toulouse have scrutinized observations from numerous satellites and aircraft instruments over the past decade, and the trend is clear. “Ice loss has continued unabated since the collapse,†Shuman said. “In recent years, the rate of elevation change has slowed a bit for some glaciers, but for others we are seeing more thinning and ice loss.â€

Some of the most dramatic changes in recent years have occurred at Hektoria and Green glaciers, tributaries on the northern edge of Larsen B drainage basin. Between 2002 and 2006, the two glaciers lost an average of 4.2 gigatons of ice per year; between 2006 and 2011, they lost 5.6 gigatons per year. In their lower reaches, the two glaciers have lost about 220 meters (720 feet) of vertical thickness since 2002.

The colorful visualization above is a digital elevation model (DEM) difference map based on satellite images acquired in 2002 (top) and 2012 (middle) by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite. The elevation model shows the dramatic thinning that has occurred since 2002. Red areas signify changes (drops) in the height of the ice. Gray indicates a lack of data, due primarily to cloud cover. ASTER creates DEMs by capturing several views of the same scene from slightly different angles, providing a stereoscopic view that can be used to reveal changes.

While changes are most evident in the elevation map, signs of the ice shelf loss are also visible by comparing the 2002 and 2012 images. Notice, for instance, how much more of the mountain ridges are visible above the ice in the 2012 image. Also, the lower edge of the Green and Hektoria glaciers—the terminus—is not visible in the 2002 image. It is visible amidst the melange of floating icebergs on the lower right side of the 2012 image. The crevasses covering the ice surfaces in the 2012 image are another sign of rapid thinning and stretching.

The Hektoria and Green glaciers are not the only glaciers in the Larsen B basin that have thinned over the past decade. The Evans, Punchbowl, and Jorum glaciers have also thinned, though not as much. A bit farther to the south, the Crane Glacier underwent 90 meters of thinning in 2004-2005, and its total elevation change—180 meters—rivals that which has occurred at Hektoria and Green in recent years.

NASA Earth Observatory image by Jesse Allen, using data from NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team. Caption by Adam Voiland.

http://earthobservatory.nasa.gov/IOTD/view.php?id=79493&src=twitter-iotd