Ice melt in part of Antarctica 'appears unstoppable,' NASA says

[A-L-E-K]

 

 

The complete melting of a major section of west Antarctica's ice sheet appears inevitable, and the process could lead to higher end-of-century global sea levels than previously anticipated, researchers said Monday.

 

 

 

The United Nations' most recent climate change report estimates sea levels could rise from about 1 foot to 3 feet by 2100, levels that could displace tens of millions of people from coastal areas around the world.

Yet that estimate largely didn't take into account melting from west Antarctica, because few studies for that area had been completed, Anandakrishnan said.

"So as this paper and others come out, the (U.N.) numbers for 2100 will almost certainly" lean closer to 3 feet, he said.

 

 

http://www.cnn.com/2014/05/12/us/nasa-antarctica-ice-melt/index.html?hpt=hp_t1

 

 

[A-L-E-K]

lol @ Florida & NYC.

 

so screwed

[TerryM]

Thank God that North Carolina will be spared.

 

Terry

[chubbs]

A number of recent papers have highlighted the instability of West Antarctic Ice sheet. Message is same for many Greenland glaciers once they speed up a slowdown is unlikely 

[Jonger]

With the IPCC assessment out... It's like a clearing house for releasing everything possible right now.

[WXheights]

Yeah but its all Ok -- you know why? It does not qualify as "as the IPCC Extreme" thank goodness

[WXheights]

I hear there are some really good sales going on the North Carolina Outerbanks where they legislated no SLR in any text books - whoopie.

[AvantHiatus]

Thank God that North Carolina will be spared.

 

Terry

An early demise is more humane? The damage has been done, but 3 feet is still livable. Economically, the costs of adaptation are massive. I can see individual cities racing to build coastal protection systems like levies and dams. We might have to cut our losses and abandon some cities next century. Invest heavily in renewables now so that we have the resources to build new infrastructure later on.

 

Tbh, in the deep future we are committed to something like 82 Ft. SLR at current CO2 levels. By the deep future I mean 300-1000 years depending on feedbacks.

 

 

Atmospheric CO2 concentration as of 2011 was around 392 ppm, and based upon that and the carbon dioxide/sea level relationship revealed in their research, Foster & Rohling (2013) calculated that long-term sea level rise will reach 24 metres (+7/-15 metres at 68%confidence) above present-day sea level once the planet has fully responded to the warming. This is likely to be achieved through extensive disintegration of the West Antarctic and Greenland ice sheets, and a substantial part of the coastal sector of the East Antarctic ice sheet.

The existing land-based ice is equivalent to 60-70 metres, so the loss of 24 metres of sea level worth of ice suggests that over a third of the ice sheet volume may already be committed to disintegration. As noted in the introduction, this dramatic response represents the long-term consequences of human industrial activity and reinforces the concept that atmospheric CO2 is Earth's main temperature control knob.

 

 

 

 

I hear there are some really good sales going on the North Carolina Outerbanks where they legislated no SLR in any text books - whoopie.

Yeah, it's all governmental lobbyists. They only focus on the bottom-line and maximizing profit. 

[frosty]

I would not trust or believe a word NASA have to say after the 1986 horrific shuttle disaster.

Their lies at trying to cover up their mistakes is unforgiveable and also the American government

for not making them stand trial. utterly disgraceful.

[Jonger]

The one thing about sea level rise, its slow..... VERY slow.

 

Reminds me of the scene from Austin Powers where the security guard gets flattened with the steam roller at a half a mile an hour.

 

Not that I ultimately buy into this article, but the whole mitigation effort could be done. Sea level has been rising for hundreds of years and will probably continue to until the next ice age.

[A-L-E-K]

The one thing about sea level rise, its slow..... VERY slow.

 

Reminds me of the scene from Austin Powers where the security guard gets flattened with the steam roller at a half a mile an hour.

 

Not that I ultimately buy into this article, but the whole mitigation effort could be done. Sea level has been rising for hundreds of years and will probably continue to until the next ice age.

 

 

 

you say a version of this in every thread

[Jonger]

you say a version of this in every thread

 

Well, its true in every thread I say it in.

 

 

[A-L-E-K]

really glad i don't live on the coast, we're so boned

 

http://www.newyorker.com/online/blogs/elements/2014/05/the-west-antarctica-ice-sheet-melt-defending-the-drama.html

 

 

 

 

But the unfortunate fact about uncertainty is that the error bars always go in both directions. While it is possible that the problem could turn out to be less serious than the consensus forecast, it is equally likely to turn out to be more serious. In fact, it increasingly appears that, if there is any systemic bias in the climate models, it’s that they understate the gravity of the situation. In an interesting paper that appeared in the journal Global Environmental Change, a group of scholars, including Naomi Oreskes, a historian of science at Harvard, and Michael Oppenheimer, a geoscientist at Princeton, note that so-called climate skeptics frequently accuse climate scientists of “alarmism” and “overreacting to evidence of human impacts on the climate system.” But, when you actually measure the predictions that climate scientists have made against observations of how the climate has already changed, you find the exact opposite: a pattern “of under- rather than over-prediction” emerges. The scholars attribute this bias to the norms of scientific discourse: “The scientific values of rationality, dispassion, and self-restraint tend to lead scientists to demand greater levels of evidence in support of surprising, dramatic, or alarming conclusions.” They call this tendency “erring on the side of least drama,” or E.S.L.D. for short.

 

 

 

“Scary,” Stefan Rahmstorf, a professor of physics of the oceans at Potsdam University, who was not involved in either paper, tweeted. “One of the feared tipping points of the climate system appears to have been crossed.”

[ORH_wxman]

That link sounds really scary.

 

 

We're already screwed.

[A-L-E-K]

ORH is the king of ESLD

[Jonger]

Sounds like another paper trying to attribute a natural process into a new "unprecedented" finding.... "Unprecedented", the new favorite word from the alarmist side of the debate.

[ORH_wxman]

Sounds like another paper trying to attribute a natural process into a new "unprecedented" finding.... "Unprecedented", the new favorite word from the alarmist side of the debate.

 

 

The SLR debate is funny...there's always a new finding in either side of the coin. We've been locked into a sizeable SLR for like a century now. Its not all natural though...that is incorrect too. But a significant portion of it is.

 

When it comes to Antarctica studies though, its easy to be skeptical since it is the least understood climate system of any region on the planet. Claims of huge accelerations in the short term are usually small probability. If you actually read the papers that are linked in some of these news releases, you'll see that it takes thousands of years to reach the end game.

 

Media press releases on papers are usually pretty bad sources for the paper's findings. It also depends on which press release you read too.

[chubbs]

15 years ago Greenland and Antarctica were thought to contribute only modestly to sea level rise this century under a range of AGW scenarios. Now it is understood that both ice sheets are losing mass at an increasing rate. There is still considerable uncertainty but the trend is to shift the cone of expected SLR this century to higher values and to expand the upper tail. This is a particularly difficult area for future projections because a shift in the buttressing of key glaciers can have a dramatic non-linear impact.

[The_Global_Warmer]

Who  cares how many meters the sea level rises by 2100, 2150, 2200....

 

Who cares if hundreds of millions of humans are displaced from their home lands.

 

Who cares if millions of animals go extinct or lose their habitat.

 

Who cares if billions of humans no longer have access to fresh water with no more land ice.

 

 

As long as I get my snow.

 

 

Oh look a backdoor cold front in MAY = YAY. 

 

Proof AGW is made up.

 

YAY

[Jonger]

Who  cares how many meters the sea level rises by 2100, 2150, 2200....

 

Who cares if hundreds of millions of humans are displaced from their home lands.

 

Who cares if millions of animals go extinct or lose their habitat.

 

Who cares if billions of humans no longer have access to fresh water with no more land ice.

 

 

As long as I get my snow.

 

 

Oh look a backdoor cold front in MAY = YAY. 

 

Proof AGW is made up.

 

YAY

 

Here's how SLR could sneak up on us.

 

[bluewave]

http://dotearth.blogs.nytimes.com/2014/05/12/keep-in-mind-scientific-and-societal-meanings-of-collapse-when-reading-antarctic-ice-news/

 

 

Take the Science paper: “Marine Ice Sheet Collapse Potentially Under Way for the Thwaites Glacier Basin, West Antarctica.” Using ice-flow models and observations, the researchers, led by Ian Joughin of the University of Washington, concluded: 

Except possibly for the lowest-melt scenario, the simulations indicate that early-stage collapse has begun. Less certain is the time scale, with the onset of rapid (>1 mm per year of sea-level rise) collapse in the different simulations within the range of 200 to 900 years.

To translate a bit, that means sometime between 200 and 900 years from now the rate of ice loss from this glacier could reach a volume sufficient to raise sea levels about 4 inches (100 millimeters) a century. At that point, according to the paper, ice loss could pick up steam, with big losses over a period of decades.* But in a phone conversation, Joughin said the modeling was not reliable enough to say how much, how soon.

“Collapse is a good scientific word,” he told me, “but maybe it’s kind of a bad word” in the context of news. There’s more on this work in a well-written news release from Joughin’s university.

[Insert, May 14, 12:00 p.m. | Joughin sent this followup thought today: In defense of collapse, if I say, "The collapse of the Roman Empire," you all pretty much understand what I mean and am talking about about a timescale similar to that for the WAIS. And I think most members of the public would too. If collapse can't refer to extended periods such as decades to centuries, someone should contact Jared Diamond and ask him to change the title of his bestseller.

And someone should also talk to the astronomers: "The collapse to a white dwarf takes place over tens of thousands of years, (Wikipage on gravitational collapse)". I think if we are clear about the time scales, the public is smart enough to figure out what we mean (that doesn't mean we shouldn't be cautious with how we word things).]

NASA has posted a heap of helpful context and description of the Geophysical Research Letters paper, written by Eric Rignot at the University of California, Irvine, and collaborators. In a NASA recording of a telephone conference call with reporters, Rignot tried to emphasize why the most familiar definition of “collapse” was inappropriate in this case:

Collapse in the imagination of most people sounds like a catastrophic event that is going to happen in the next few years. We are talking about a retreat that is unstoppable because we think we have enough evidence to say that these glaciers will keep retreating for decades and even centuries to come…. We’re talking about a slow degradation of ice in this part of Antarctica.

[The_Global_Warmer]

I hear there are some really good sales going on the North Carolina Outerbanks where they legislated no SLR in any text books - whoopie.

 

 

That is when people deserve what is coming to them.

 

I emphasize with the folks who live there and know how horribly screwed they are because they have to deal with that level of ignorance.

 

What is more sad is that those officials will be dead when their horrible ignorance costs so many other people.

 

In fact those officials who are responsible for these terrible choices get well compensated now to fuc* others later.

 

If only they lived long enuf to be held accountable for doing this.

[Jonger]

That is when people deserve what is coming to them.

 

I emphasize with the folks who live there and know how horrible screwed they are but they have to deal with that level of ignorance.

 

What is more sad is that those officials will be dead when their horrible ignorance costs so many other people.

 

In fact those officials who are responsible for these terrible choices get well compensated now to fuc* others later.

 

If only they lived long enuf to be held accountable for doing this.

 

Their children and their grand children as well. 

[ORH_wxman]

 

http://dotearth.blogs.nytimes.com/2014/05/12/keep-in-mind-scientific-and-societal-meanings-of-collapse-when-reading-antarctic-ice-news/

 

 

Take the Science paper: “Marine Ice Sheet Collapse Potentially Under Way for the Thwaites Glacier Basin, West Antarctica.” Using ice-flow models and observations, the researchers, led by Ian Joughin of the University of Washington, concluded: 

Except possibly for the lowest-melt scenario, the simulations indicate that early-stage collapse has begun. Less certain is the time scale, with the onset of rapid (>1 mm per year of sea-level rise) collapse in the different simulations within the range of 200 to 900 years.

To translate a bit, that means sometime between 200 and 900 years from now the rate of ice loss from this glacier could reach a volume sufficient to raise sea levels about 4 inches (100 millimeters) a century. At that point, according to the paper, ice loss could pick up steam, with big losses over a period of decades.* But in a phone conversation, Joughin said the modeling was not reliable enough to say how much, how soon.

“Collapse is a good scientific word,” he told me, “but maybe it’s kind of a bad word” in the context of news. There’s more on this work in a well-written news release from Joughin’s university.

[Insert, May 14, 12:00 p.m. | Joughin sent this followup thought today: In defense of collapse, if I say, "The collapse of the Roman Empire," you all pretty much understand what I mean and am talking about about a timescale similar to that for the WAIS. And I think most members of the public would too. If collapse can't refer to extended periods such as decades to centuries, someone should contact Jared Diamond and ask him to change the title of his bestseller.

And someone should also talk to the astronomers: "The collapse to a white dwarf takes place over tens of thousands of years, (Wikipage on gravitational collapse)". I think if we are clear about the time scales, the public is smart enough to figure out what we mean (that doesn't mean we shouldn't be cautious with how we word things).]

NASA has posted a heap of helpful context and description of the Geophysical Research Letters paper, written by Eric Rignot at the University of California, Irvine, and collaborators. In a NASA recording of a telephone conference call with reporters, Rignot tried to emphasize why the most familiar definition of “collapse” was inappropriate in this case:

Collapse in the imagination of most people sounds like a catastrophic event that is going to happen in the next few years. We are talking about a retreat that is unstoppable because we think we have enough evidence to say that these glaciers will keep retreating for decades and even centuries to come…. We’re talking about a slow degradation of ice in this part of Antarctica.

 

 

 

Yep, but don't let the science of it get in the way of a nice scare story.

[chubbs]

Below is another quote from Dr. Joughin. It is a slow process until a threshold has been crossed. This is one of those uncertain low probability high risk scenarios that is very difficult to deal with

http://www.science20.com/news_articles/west_antarctic_ice_sheet_collapse_is_only_a_few_centuries_away-136386

UW researchers combined that data with their own satellite measurements of ice surface speeds. Their computer model was able to reproduce the glacier's ice loss during the past 18 years, and they ran the model forward under different amounts of ocean-driven melting.

The place where the glacier meets land, the grounding line, now sits on a shallower ridge with a depth of about 2,000 feet (600 meters). Results show that as the ice edge retreats into the deeper part of the bay, the ice face will become steeper and, like a towering pile of sand, the fluid glacier will become less stable and collapse out toward the sea.

"Once it really gets past this shallow part, it's going to start to lose ice very rapidly," Joughin said.

The study considered future scenarios using faster or slower melt rates depending on the amount of future warming. The fastest melt rate led to the early stages lasting 200 years, after which the rapid-stage collapse began. The slowest melt rate kept most of the ice for more than a millennium before the onset of rapid collapse. The most likely scenarios may be between 200 and 500 years, Joughin said.

"All of our simulations show it will retreat at less than a millimeter of sea level rise per year for a couple of hundred years, and then, boom, it just starts to really go," Joughin said.

Researchers did not model the more chaotic rapid collapse, but the remaining ice is expected to disappear within a few decades.

[csnavywx]

Below is another quote from Dr. Joughin. It is a slow process until a threshold has been crossed. This is one of those uncertain low probability high risk scenarios that is very difficult to deal with

http://www.science20.com/news_articles/west_antarctic_ice_sheet_collapse_is_only_a_few_centuries_away-136386

UW researchers combined that data with their own satellite measurements of ice surface speeds. Their computer model was able to reproduce the glacier's ice loss during the past 18 years, and they ran the model forward under different amounts of ocean-driven melting.

The place where the glacier meets land, the grounding line, now sits on a shallower ridge with a depth of about 2,000 feet (600 meters). Results show that as the ice edge retreats into the deeper part of the bay, the ice face will become steeper and, like a towering pile of sand, the fluid glacier will become less stable and collapse out toward the sea.

"Once it really gets past this shallow part, it's going to start to lose ice very rapidly," Joughin said.

The study considered future scenarios using faster or slower melt rates depending on the amount of future warming. The fastest melt rate led to the early stages lasting 200 years, after which the rapid-stage collapse began. The slowest melt rate kept most of the ice for more than a millennium before the onset of rapid collapse. The most likely scenarios may be between 200 and 500 years, Joughin said.

"All of our simulations show it will retreat at less than a millimeter of sea level rise per year for a couple of hundred years, and then, boom, it just starts to really go," Joughin said.

Researchers did not model the more chaotic rapid collapse, but the remaining ice is expected to disappear within a few decades.

Right, it's slow until enough CDW-driven melt has destabilized the glacier enough to cause it to fail spectacularly via gravity-driven structural collapse (massive iceberg events, not unlike Heinrich events). Paleoclimate evidence thusfar suggest that the chaotic stage is very quick (decades). The question is how long it takes. I'm in in the camp that Greenland is relatively stable and the WAIS is very vulnerable, especially the PIG/Thwaites complex, which have extensive, deeply retrograding beds and little in the way of stabilizing features (like extensive ice shelves). They are also exposed to rapidly warming circumpolar deep water, especially in El Nino years.

[bluewave]

Yep, but don't let the science of it get in the way of a nice scare story.

 

I am really glad that I don't have the job of trying to make very long range forecasts for the Southern Hemisphere.

 

 

http://www.nature.com/nclimate/journal/v4/n5/full/nclimate2219.html

For far too long the climate science community has grappled with an inconvenient truth: the vast majority of the datasets used to constrain temperature trends of the recent past come from the Northern Hemisphere. Over a dozen reconstructions of Northern Hemisphere temperature spanning the past millennium exist and have played a critical role in distinguishing natural from anthropogenic climate change. However, the extent to which recent temperature variations in the Northern Hemisphere resemble those in the Southern Hemisphere remains unclear. Such information is critical to a complete understanding of the mechanisms of global, rather than hemispheric, climate change. Although the new reconstruction resembles the Northern Hemisphere reconstructions in some key aspects — the anomalous nature of twentieth century warming being one of them — it also suggests that temperatures in the two hemispheres may have differed more than they have agreed over the past millennium.

However, the new reconstruction of Southern Hemisphere temperature1 suggests that the climate model simulations of past climate systematically underestimate the magnitude of natural climate variability in the Southern Hemisphere. At first glance, the reconstruction contains the same basic features of the Northern Hemisphere family of reconstructions — a centuries-long cooling into the seventeenth century, and a twentieth-century warming of unprecedented duration and magnitude. But a close comparison between the Northern and Southern Hemisphere reconstructions reveals many intervals when the two series diverge for decades at a time. Notably, some of these differences occur following large volcanic eruptions, when the Northern Hemisphere cools significantly but the Southern Hemisphere does not, at least according to the new reconstruction1. The fact that many of these differences occur within the past 400 years, when the data networks from both hemispheres are most robust, makes it less likely that such temperature differences are artifacts of poor data coverage. That said, it is possible that small but cumulative age errors in single palaeoclimate records may smear out interannual variability in large-scale temperature reconstructions — currently the topic of vigorous debate.

If the new reconstruction of Southern Hemisphere temperature is accurate, then estimates of climate sensitivity — the response of global temperature change to a given amount of external radiative forcing — may be lower than those calculated based solely on Northern Hemisphere reconstructions. Indeed, instrumental temperature data suggest that warming in the Northern Hemisphere has been greater than that observed in the Southern Hemisphere over the past two decades — a feature reproduced in the current suite of climate models11. Therefore, this hemispheric asymmetry may be a fundamental feature of the climate system’s response to a change in radiative forcing, whereby the ocean-dominated Southern Hemisphere acts as a buffer of sorts to global temperature change on decadal to centennial timescales. On the other hand, Neukom et al. propose that divergent hemispheric temperatures arise from strong natural climate variability in the Southern Hemisphere, and have been a constant feature of the past millennium.

Given the new information now available from the Southern Hemisphere, climate scientists must consider a larger role for natural climate variability in contributing to global temperature changes over the past millennium. While the new reconstruction brings strong additional support to the phrase ‘anthropogenic global warming’, it also highlights the limits of our current ability to understand, and predict, global temperature variations from decade to decade. In other words, global temperatures will warm appreciably by 2100, but the road may be bumpy and full of surprises.

[The_Global_Warmer]

The way GIS is set up probably make it more stable versus a massive destabilization and collapse.

 

However GIS is is vulnerable by other means.

 

1.  Ice albedo feedback.  Including dark pollutants.

 

So far only a tiny fraction of the GIS ice sheet surface area has seen it's albedo permanently altered from this process.  The dark materials can't be flushed.  They stay embedded and pile up on each other within the mushy melting ice in Summer then are frozen in position in Fall.  Only to be there when the fresh snow is melted off.

 

Once that happens local melting/heating dramatically increases. 

 

 

 

 

 

The result is an ice sheet that looks like this below.

 

The scary part is that ice cores show this soot is embedded within the ice everywhere if enuf of the surface snow/ice was melted.  On top of that pollution from humans and natural forest fires also comes here.

 

Recently Russian forest fires were bad and impurities from those fires in Summer landed on GIS.  A lot of people first thought is that is natural.  Which is true.  Most of the dark material on GIS is natural and not man made. 

 

However the triggering of it being exposed and being a major feedback is driven by Man made warming.

 

Right now we are pretty secure.  The exposed ice layer is mostly below 1500M or 5000FT.  However the rest of the ice sheet is mostly 1501 to 2500M which a small part above that.

 

So the area that this issue has reached is not linear. But very sloped until you get into the 1700M range.

 

My point is the next 500M to succumb to this which they will are likely 10-15 times larger in surface area then the 0-1500M range that has been melted down to that level.  And not everywhere below 1500M has been exposed.  Large areas of Northern GIS have a more gentle slope that will be exposed as well in spite of their latitude.

 

However the big change will be over the Southern 1/3rd when it warms up enuf to expose larger surface areas to this.

 

 

 

 

In some areas of the ice sheet, by the time winter snow cover melt away, bare glacier ice is exposed. Where impurities congregate, the surface albedo drops below 30%.

 

 

 

 

 

[The_Global_Warmer]

For those who are interested in watching this unfold in real time.

 

This season might be a good example of it.

 

GIS melt CLIMO shows the melt percentage not really rising over 3-4% until the very end of May.  Starting tomorrow that is about to be demolished.

 

 

 

Everything below 1500M where the 0C line reaches will see direct melting from the surface temperatures.  However that doesn't include the effect the ridge(clear skies) will have with direct solar insolation which is around 425W/M2+ right now in this region.

 

 

Some areas below 1000M will see surface snow rapidly melt forming melt ponds by the end of the period below.  Regions above 1500M won't see ice melt.  But they will see snow melt and obviously no fresh snow. 

 

We can't forget either the local ssts will probably run near record warmth or above as this goes on.  That is just another feedbacking heat source that grows stronger as the Earth warms and direct solar insolation increases.

 

[Jonger]

What does your post have to do with Antarctica?