Tuesday, August 7, 2012

Greenland meltdown could happen in only 67,000 years!

A 'Scientific' American article, Greenland Meltdown Driven by Collapse of Glaciers at Ocean Outlets, begins with the scary proclamation, “the ice sheet as a whole has lost some 36 billion metric tons of ice each year in recent years.” However, the New Zealand Climate Conversation Group calculates this amounts to an annual loss of only 0.00148% of the Greenland ice cap and would require only 67,222 years to meltdown at that rate [if an ice age doesn't occur beforehand].

Furthermore, 'Scientific' American conveniently fails to point out

1. The authors of the study said in the abstract:

“Our results suggest that the ice mass changes in this sector were primarily caused by short-lived dynamic ice loss events rather than changes in the surface mass balance. This finding challenges predictions about the future response of the Greenland Ice Sheet to increasing global temperatures.”

2. This is normal behavior for ice caps since the last ice age

3. Meanwhile, the interior of Greenland is growing by 5.4 cm/yr

4. In Antarctica, home of 90% of the world's ice, sea ice extent is growing and the ice cap is projected to gain ice despite possible warming.


Ice cap scare – just 67 millenia left
Richard Treadgold | August 6, 2012
Inside the Greenland ice cap
Yes, that’s right, only 67,000 years to go.
David Biello wrote an unlovely piece of non-science a few days ago which Scientific American was happy to publish.
It seems the once-reliable journal doesn’t care about standards now. The headline was uncompromising:Greenland Meltdown Driven by Collapse of Glaciers at Ocean Outlets.
To call what follows a “meltdown” is a hoax, a fraud, a betrayal, a cheat, a perfidy, a sham and a swindle. Not to mention several dozen other words in the thesaurus which all mean deceit.
The subheading gives voice to the first prevarication:The interactions between the island’s glaciers and the surrounding seas may be driving ice loss, according to aerial photographs.

Global weirding

But the opening paragraph got down to brass tacks:“the ice sheet as a whole has lost some 36 billion metric tons of ice each year in recent years.” We shall look at what that means. First, though, consider the next comment: “Thanks to weird weather, nearly the entire ice-covered surface of the world’s largest island melted for a period this year.”
The word “weather” is a hyperlink, as though they have some scientific explanation of weird weather, but they mislead us again. You end up on a general weather page that doesn’t mention weird weather. I’ve learned that the strange melting episode affected only the very surface of the ice cap, which re-froze within hours. The melt was caused by a warm weather system which is not unusual – it occurs about every 150 years.
But “global weirding” is the new codeword for global warming, and it’s applied to any slightly unusual weather event. Try it yourself the next time it rains when you hoped for sun, or fog appears just when you wanted rain. Call it global weirding and notice how people listen to you. Magic!

But it is shrinking

Anyway, this slight mid-summer melting is not because of anything we’ve done and there is no need for alarm.
But the ice cap has lost about 36 billion metric tons of ice a year recently. It sounds a lot, but let’s put it into perspective. The first question in my mind is: how does the loss compare to the mass of the whole ice cap? It’s easy to find out.
Wikipedia tells us that the volume of the Greenland ice cap is 2,850,000 cubic kilometres, or 2.85 × 106 km3. It gives values for the density of glacial ice from which I chose 850 kg/m3 (less than liquid water at 1000 kg/m3. Finally, there are 109 cubic metres in one cubic kilometre.

Caution: raw maths ahead

So:
Density of one cubic km of ice cap = 850 × 109 kg/km3
Total ice cap volume = 2.85 × 106 km3
Multiply = 2.42 × 1018 kg
Convert to tonnes = 2.42 × 1015 T
Or 2420 trillion tonnes.
It’s currently losing 36 billion tonnes per year.
Or, a 2,420,000,000,000,000 kg ice cap is losing 36,000,000,000 kg per year.
I calculate that to be an annual loss of 0.00148% of the ice cap.
That’s not very much at all, Winifred. Quite trivial, in fact.

How long will the ice last?

Correct me if I’m wrong, but it seems that at that rate there are only 67,222 years of ice cap left.

67,222 years

Oh dear. I wonder if we could get the mainstream media to publish this alarming news?
Possibly not.
What if we just mentioned that it’s melting, without pointing out how slowly?
They’d probably fall for it – their reporters don’t know any maths.


Future Greenland doom

Richard Treadgold | August 7, 2012
The author of the paper that prompted Scientific American’s alarming claim of a “meltdown” sounds caution over predicting the demise of the Greenland ice sheet.
Is it a turnaround? No, because in the abstract we read:
“Our results suggest that the ice mass changes in this sector were primarily caused by short-lived dynamic ice loss events rather than changes in the surface mass balance. This finding challenges predictions about the future response of the Greenland Ice Sheet to increasing global temperatures.”
It’s just that “Scientific” American didn’t mention it. I wonder why not?
Now, at Voice of America, geologist and co-author, Kurt Kjaer, of the Denmark Natural History Museum, says: “It is too early to proclaim the ice sheet’s future doom.”
The researchers say a longer and more detailed record of Greenland’s past is needed to better predict the future of the glacier-covered landmass.
That sounds reasonable. It should give scientists who have been predicting more drastic near-term futures pause for thought.
So that’s another peer-reviewed paper by a proper scientist refuting claims of ice-borne peril and disastrous sea level rise. A paper that’s based on observations, not modelling.
Remember this when the alarmists yet again cry wolf.


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