Arguments
Skeptical Logic Can't Save Greenland Ice - for that you need to stop climate change
Posted on 15 October 2010 by gpwayne
Climate change skeptics like Marc Morano employ gross exaggeration to dismiss or diminish the potential disruption that climate change is likely to bring about. In the Inhofe EWP press blog, Morano made much of this statement:
“...evidence that suggests the frozen shield covering the immense island survived the Earth’s last period of global warming”
Irrespective of what it means to claim the ice sheet ‘survived’ (a rather unqualified claim since survival could be taken to mean that 99% or 1% of the ice was left), it is generally recognised that a complete melt-down of the Greenland ice sheet is far less likely than partial melting. The time-scales over which such a dramatic and complete failure could occur must also be reckoned in centuries rather than decades. Given how much uncertainty surrounds even the accurate measurement of negative mass balance (how much the ice is reducing per year), projections on the century scale are too speculative to be helpful when considering the current problem, which is sea level rise.
Sea level rise will depend on how much water is currently held in the Greenland ice sheet, because the sheer volume of water is so immense that even a small loss of ice will produce considerable rises in sea level – and concerns about loss of mass from ice sheets focuses on sea level rise because this is one of the most serious threats climate change may invoke.
So let’s consider the ice sheets, individually and collectively. Estimates suggest that if the Greenland ice sheet was to melt away to nothing, sea levels would rise around 7 metres. To put that a different way, a loss of just one percent of the ice cap would result in a sea level rise of 7cm. Consider this in context: if the West Antarctic Ice Sheet (WAIS) were to melt, this would add around 6 metres to sea levels. If the East Antarctic Ice Sheet (EAIS) were to melt, seas would rise by around 70 metres. So a mere 1% loss of ice from these three sources would produce a likely increase in sea levels of around 83cm - from these ice formations alone.
It is important when considering the impact of ice sheet mass balance to bear in mind that a global phenomenon like climate change will produce negative mass balance at both poles, and the shrinking glaciers will also contribute to sea level increases.
While the complete disappearance of Greenland’s ice sheet is hard to predict and the probability lower than a partial collapse, it is clear that even a relatively small loss of ice through melting will produce considerable, and very disruptive, increases in sea levels.
This post is the Basic Version (written by Graham Wayne) of the skeptic argument "Greenland ice sheet won't collapse".
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Modeled configuration of the Greenland Ice Sheet today (left) and in MIS 5e (right), from Otto-Bliesner (2006).
The reduction in size of the ice sheet during MIS 5e probably added 3-4 m to global sea levels, which accounts for about half of the 6+ m total rise in sea levels during that interglacial (Alley 2010).
For what it's worth, the Greenland ice sheet appears to mostly or entirely have disappeared during an earlier interglacial (MIS-11, around 400,000 years ago) that is considered to be the best analog for our current interglacial.
I'm not sure whether the different extents of the ice sheet in MIS-11 vs MIS-5e was due to its longer duration (MIS-11 was a particularly long interglacial), warmer summers in Greenland, a combination of both, or something else.
"The Arctic is experiencing faster melting. If this were to go [points to map of East Antarctica], sea level worldwide would go up twenty feet. This is what would happen in Florida. Around Shanghai home to forty million people, the area around Calcutta sixty million. Here is Manhattan. The Word Trade Center Memorial would be under water. Think of the impact of a couple of hundred thousand refugees and then imagine a hundred million. [caption: NOTHING IS SCARIER THAN THE TRUTH]"
One should ask Is Al Gore's An Inconvenient Truth accurate?
Dr Stott, the Defendant's expert, is right when he says that:
"Al Gore's presentation of the causes and likely effects of climate change in the film was broadly accurate."
(Rebuttal written by gpwayne. Last updated on 7 October 2010)
Yes, twenty feet is broadly accurate. If a strawman says so, it must be true.
It is substantially founded upon scientific research and fact, albeit that the science is used, in the hands of a talented politician and communicator, to make a political statement and to support a political programme.
Al Gore is a successful politician who presented a film, his training and experience suitable to the task. To invoke Gore is a way to obfuscate about climate science, for which Gore has neither responsibility, claim nor blame.
Instrumental record removed, spaghetti graphs are awful.
Hiding the incline was not a good job, Péter, and not much deconstruction can be seen.
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