Tuesday, 17 April 2012

Making it up (1) - "Study finds Greenland's ice cover is sliding into the ocean"

This is the start of a new series to run in parallel with "Disconnects in Logic". Both have and will be a source of amusement and debunking hyperbole, unjustified conclusions and predictions, and plain outright lies at the same time.

"Click Green" (you're ahead of me, I can tell) trumpets the apocalyptic headline "Study finds Greenland's ice cover is sliding into the ocean" . The contradiction between headline and article is striking - it's becoming common when the environment, wildlife, "climate change" or "global warming" are discussed, or new research summarised. Apart from the fact that most of the Greenland ice sheet covers the depressed interior of the landmass, and has as much chance of "sliding into the ocean" as a pool ball in a pocket has of "sliding onto the table", what does the first paragraph actually say?
Like snow sliding off a roof on a sunny day, the Greenland Ice Sheet may be sliding faster into the ocean due to massive releases of meltwater from surface lakes, according to a new study by the University of Colorado Boulder-based Cooperative Institute for Research in Environmental Sciences.
As usual, the caveat is "may be", which as so often is the case in alarmist articles, becomes "is" in the headline.
During a typical catastrophic lake drainage, about 1 million cubic meters of meltwater - which is equivalent to the volume of about 4,000 Olympic swimming pools - funnels to the ice sheet's underside within a day or two. Once the water reaches the ice sheet's belly that abuts underlying rock, it may turn the ice-bed surface into a Slip 'N Slide, lubricating the ice sheet's glide into the ocean. This would accelerate the sea-level rise associated with climate change.
Alternatively, however, the lake drainages may carve out sub-glacial "sewers" to efficiently route water to the ocean. "This would drain the ice sheet's water, making less water available for ice-sheet sliding," Colgan said. That would slow the ice sheet's migration into the ocean and decelerate sea-level rise.
"Alternatively, however..." means they don't know, and what's more, the researchers openly admit it.
"Lake drainages are a wild card in terms of whether they enhance or decrease the ice sheet's slide," Colgan said. Finding out which scenario is correct is a pressing question for climate models and for communities preparing for sea-level change, he said.
So they, we, (and the "Click Green" author) don't actually know what's happening. All that is known is that the meltwater "lakes" suddenly disappear, and it's assumed they've drained away. I say assumed, because
For the study, the researchers developed new feature-recognition software capable of identifying supraglacial lakes in satellite images and determining their size and when they appear and disappear. "Previously, much of this had to be double-checked manually," Colgan said. "Now we feed the images into the code, and the program can recognize whether a feature is a lake or not, with high confidence and no manual intervention."
If such a lake "disappears" then, it might be because the water's drained away, as postulated, or possibly it's refrozen, and wouldn't be recognised by the software. First they don't know what the drainage mechanism is, whether meltwater is actually "lubricating" the base of the ice, and the real "sceptic in the room", don't even know if the lake hasn't simply refrozen. Headline fail, alarmism alert, interesting study, shame about the lack of any firm conclusions.

I really aught to start a third new series "Displaying Your Ignorance", 'cos I LOL when I saw this "schoolboy howler" on redOrbit - "Greenland Slipping Away"
Massive releases of meltwater from surface lakes may be causing Greenland to slide ever faster into the ocean, according to a new study by the University of Colorado Boulder-based Cooperative Institute for Research in Environmental Sciences (CIRES).
What's Greenland sliding on I wonder, Santa's Sleigh? Hold on tight, Greenlanders! Wheeee!

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