Global meltdown

[Barrett808]

Global meltdown
Fred Pearce
Wednesday August 30, 2006
The Guardian

Richard Alley's eyes glint as we sit in his office in the University of Pennsylvania discussing how fast global warming could cause sea levels to rise. The scientist sums up the state of knowledge: "We used to think that it would take 10,000 years for melting at the surface of an ice sheet to penetrate down to the bottom. Now we know it doesn't take 10,000 years; it takes 10 seconds."

That quote highlights most vividly why scientists are getting panicky about the sheer speed and violence with which climate change could take hold. They are realising that their old ideas about gradual change - the smooth lines on graphs showing warming and sea level rise and gradually shifting weather patterns - simply do not represent how the world's climate system works.
Dozens of scientists told me the same thing while I was researching my book The Last Generation. Climate change did not happen gradually in the past, and it will not happen that way in the future. Planet Earth does not do gradual change. It does big jumps; it works by tipping points.

The story of research into sea level rise is typical of how perceptions have changed in the past five years. The conventional view - you can still read it in reports from the UN's Intergovernmental Panel on Climate Change - holds that sea levels will start to rise as a pulse of warming works its way gradually from the surface through the 2km- and 3km-thick ice sheets on Greenland and Antarctica, melting them. The ice is thick and the heat will penetrate only slowly. So we have hundreds, probably thousands, of years to make our retreat to higher ground.

Recent research, however, shows that idea is wholly wrong. Glaciologists forgot about crevasses. What is actually happening is that ice is melting at the surface and forming lakes that drain down into the crevasses. In 10 seconds, the water is at the base of the ice sheet, where it lubricates the join between ice and rock. Then the whole ice sheet starts to float downhill towards the ocean.

"These flows completely change our understanding of the dynamics of ice sheet destruction," says Alley. "Even five years ago, we didn't know about this."

(more)

http://environment.guardian.co.uk/climatechange/story/0,,1860560,00.html

[Boomer]

1. K&R

This should be headline news, but it seems the JonBenet murder case is more enthralling to the masses.

[Dogmudgeon]

2. Now THAT'S some "Abrupt Climate Change"

And here, I was thinking in terms of a couple decades.

Excellent find, Barrett! :thumbsup:

--p!

[Buzz Clik]

3. No one is going to challenge this ruse?

"We used to think that it would take 10,000 years for melting at the surface of an ice sheet to penetrate down to the bottom. Now we know it doesn't take 10,000 years; it takes 10 seconds."

He is not saying that the ice sheet will melt in ten seconds. He's saying that warm water that manages to penetrate a deep crevasse could potentially break off a single chunk of ice in ten seconds. That depends on many assumptions -- and still applies to small portions of the sheet.

good lord.

[Boomer]

4. And your point is what,?

>> He is not saying that the ice sheet will melt in ten seconds.

No, he's not. And?

What "ruse" is involved in stating a scientific fact? At no point does anyone, in the article or in this thread, claim that glaciers are going to melt in 10 seconds. It's hardly fair to be indignant over a implication that was never made. The only person who mentioned this absurd claim was you.

But the fact remains -- the mechanics of melting are happening MUCH faster than anticipated. Which means that the melting of the ice sheet is happening much faster than originally predicted. Not ten seconds, not even ten years, but much, much faster than 10,000 years.

So we're now down to contemplating the possibility of a few hundred years or less for the melting of the ice sheets. Not soon enough for me to worry about myself in this landscape, but anyone with young children might have a small twinge of dread about the world they'll face in the last half of this century.

[Buzz Clik]

6. Your analysis is correct, but the Guardian stated it differently.

Your comment is correct: "So we're now down to contemplating the possibility of a few hundred years or less for the melting of the ice sheets. Not soon enough for me to worry about myself in this landscape, but anyone with young children might have a small twinge of dread about the world they'll face in the last half of this century."

But here's the context created by the Guardian:

"We used to think that it would take 10,000 years for melting at the surface of an ice sheet to penetrate down to the bottom. Now we know it doesn't take 10,000 years; it takes 10 seconds."

That quote highlights most vividly why scientists are getting panicky about the sheer speed and violence with which climate change could take hold. They are realising that their old ideas about gradual change - the smooth lines on graphs showing warming and sea level rise and gradually shifting weather patterns - simply do not represent how the world's climate system works.
Dozens of scientists told me the same thing while I was researching my book The Last Generation. Climate change did not happen gradually in the past, and it will not happen that way in the future. Planet Earth does not do gradual change. It does big jumps; it works by tipping points.


What is actually happening is that ice is melting at the surface and forming lakes that drain down into the crevasses. In 10 seconds, the water is at the base of the ice sheet, where it lubricates the join between ice and rock. Then the whole ice sheet starts to float downhill towards the ocean.

Speed and violence? The whole ice sheet floats downhill to the ocean? We all know better. This kind of hysterical bullshit helps nothing.

[Nihil]

7. "Hysterical bullshit"? Apart from YHO?

> Speed and violence?

Yep. Speed and violence. Both are relative terms. Both are valid.
Taken in the context of the original quote it is exactly correct:

>> That quote highlights most vividly why scientists are getting
>> panicky about the sheer speed and violence with which climate
>> change could take hold. They are realising that their old ideas
>> about gradual change - the smooth lines on graphs showing warming
>> and sea level rise and gradually shifting weather patterns - simply
>> do not represent how the world's climate system works.

(My emphasis)
The "speed" is not "speed" in relation to a cheetah or sports car
but it is "speed" in comparison to geological processes (uplift,
continental drift, erosion).

The "violence" isn't "violence" in the sense of being mugged in
Central Park or the subtle treatment being issued to random Iraqi
civilians but it is "violence" in comparison to the gradual melting
and freezing cycle that had previously been assumed.


> The whole ice sheet floats downhill to the ocean?

Where do you think the ice sheet is going to go? Uphill to the sky?
Climb back into the mountains? Every coastal ice sheet has been
floating downhill to the ocean since it began. The difference now
is that the rate of "floating" has increased significantly.

> We all know better.

You obviously don't.


To repeat from the article:
>> Planet Earth does not do gradual change.
>> It does big jumps; it works by tipping points.

And when the Earth does "big jumps", the energy involved totally
trivialises everything humanity has done to date.

[Buzz Clik]

11. We'll see how it plays out, ok?

We have several posters here who are adamant that claiming that every warm day should and must be declared a potential disaster due to global warming. Others of us recommend a suspension of the hysteria and sticking only to facts. No fear-inducing words like "melting ice sheets in ten seconds", "rapid, violent climate change". State only that which can be supported.

The attempts to induce world wide fear about global warming with the tactics playing out here and in other threads will undoubtedly backfire. It is the consensus of nearly every notable scientist involved in climate change research that we are not seeing any of the strong impacts of anthropogenic global warming, nor will we for at least twenty years. In the mean time, natural warming and cooling cycles will play out. If we continue this nonsense of screaming "global warming -- run for you lives!" in the middle of this natural warming cycle, what will you say when we enter a cooling period?

Take a deep breath, stay informed, and settle down.

[Dead_Parrot]

13. I agree...

The phrase "melting ice sheets in ten seconds" has no place in a rational discussion. I can't think why you invented it.

for at least twenty years... natural warming and cooling cycles will play out... what will you say when we enter a cooling period?

I'll say "Wow, we've managed to re-define climatology to the point where 20 years is now a significant period of time". :eyes:

[Buzz Clik]

15. LOL! Now you're arguing for the sake of argument. Nevermind.

Have it your way. I said my peace.

[Boomer]

9. What Nihil said

I see nothing "hysterical" about that article or its description of possible future scenarios.

[Buzz Clik]

10. See what you want to see. I called it correctly.

[skids]

5. No that's not what he's saying.

He's saying the water can reach the bottom of the glacier in ten seconds. By falling. Not that an ice break would be caused. The reason it is a matter of concern is because said water lubricates the join between land and ice, which allows the glacier to slide into the sea faster.

There's no ruse. It's all been verified by measurement.

[NickB79]

8. Glaciers don't have to melt to raise sea levels

The water lubricates the bottom of the glaciers, allowing them to slide towards the sea rapidly. Once there, they calve into icebergs. Since we're talking about glaciers over solid land and not ice sheets, this calving will raise sea levels much more rapidly than previously thought.

The primary concern, IMO, is not that sea levels will jump feet in a matter of years, but that the massive influx of fresh water will disrupt the thermohaline cycle.

[Buzz Clik]

12. Right. And there's projections to the contrary.

A recent article in Nature projects that even in the event of global warming the amount of snowfall in the interior of the Antarctic will increase dramatically, completely offsetting the impact of the breaking off of the ice sheets.

When you look at the entire picture, it gets fuzzier.

[Dead_Parrot]

14. Got a reference? nt

[Buzz Clik]

18. yes.

"Snowfall-Driven Growth in East Antarctic Ice Sheet Mitigates Recent Sea-Level Rise." Curt H. Davis, Yonghong Li, Joseph R. McConnell, Markus M. Frey,3 Edward Hanna. Science, June 24, 2005, 308:1898-1901.


And summarizing the need for reasonable research in the same issue:

"To respond appropriately to the threat of sea level rise, policy-makers urgently need accurate predictions of sea level rise as the sum of all its contributions. Davis et al. (1) provide the first observation-based estimate
of one important contribution, that of the East Antarctic ice sheet. This is a huge step forward, but to reduce our uncertainty, much work is required to determine the underlying cause and likely future of each and every contribution, both positive and negative, in Antarctica and elsewhere."
--D.G. Vaughan, Science, June 24, 2005, page 1877.

[muriel_volestrangler]

27. However, they do not say it "completely offsets" ice sheet disintegration

as you had claimed - and the title word 'mitigates' tells us that, too. Comments from the lead author in an article at the time:

"The East Antarctic ice sheet absorbed ocean mass in the form of snowfall so, as a result, it slowed sea level rise," Curt Davis, of the University of Missouri, US, told the BBC News website.

"It is a modest slowing, but it is somewhat surprising because all the other terrestrial ice masses are contributing to sea levels. This is the only one that is absorbing mass rather than contributing to it."
...
"The effect will only work for a finite period of time," Professor Davis said. "Eventually, the snow will start to melt."

Also, the overall mass of Antarctica may be decreasing, because coastal melt may be happening faster than internal ice sheet gain.

"Since sea levels are rising, that would be a reasonable assumption to make, although we don't know for sure," added Professor Davis.

http://news.bbc.co.uk/1/hi/sci/tech/4565935.stm

[Buzz Clik]

28. True. I overstated.

The impacts of increased snowfall, however, would not be trivial.

[skids]

16. That should have been hapenning already...

...but it hasn't. So now they are worried that it won't. In any case, even after it does, the permafrost melt releasing methane should quickly bring the global temperature up to the point where even that ice melts.

[Buzz Clik]

17. You really need to read up on this subject.

Your enthusiasm is admirable. Your lack of information is an impediment.

[skids]

19. I'm pretty read up.

http://www.scienceagogo.com/news/20060711004957data_trunc_sys.shtml

[Buzz Clik]

20. I see. So in the middle of all this scientific debate ...

... you stand confident in proclaiming the end of the world?

Remarkable.

From your own link: "The new study shows that current climate-change models need to be revamped if scientists are to have a more accurate representation of Antarctic weather patterns. 'The year-to-year and decadal variability of the snowfall is so large that it makes it nearly impossible to distinguish trends that might be related to climate change from even a 50-year record,' said Monaghan."

Fascinating. The scientists you're quoting are uncertain, but you are not. Care to explain?

(Here's the original reference -- your scienceagogo reference was incorrect: Monaghan et al, 2006. Science 313:827-831)

[skids]

21. Yes, I am pretty sure the crap is inches from the fan.

Like I have said many times before, it's not the sea level rise, nor the storms, that will get us. It's the shifts in the biosphere which happen much more rapidly in response to surprisingly small, by "common sense" standards, changes in the environmental system inputs.

[Buzz Clik]

22. Ah, so now you're talking about the changes in the biosphere.

Everyone else is discussing the melting of the ice sheets. Care to stay on topic?

[skids]

23. Nope. n/t

[Buzz Clik]

24. Oh. Then someone using your name must have said this:

Like I have said many times before, it's not the sea level rise, nor the storms, that will get us. It's the shifts in the biosphere which happen much more rapidly in response to surprisingly small, by "common sense" standards, changes in the environmental system inputs.

Nope. Nothing about the biosphere in that quote. (gawd)

[skids]

25. No,

...as in no I don't care to "stay on topic." Frankly I don't care to even bother with your posts at this point, for reasons obvious in this thread and others.

[Buzz Clik]

26. Indeed, the reasons are obvious:

"Frankly I don't care to even bother with your posts at this point"

When you cannot win an argument without changing the subject, be sure to blame your opponent. I agree -- your reasons are obvious.