Another day, another melting glacier scare
Burn the words, "Pine Island Glacier" into your list of Gonzo Climate Reports.
For the Climatoides are at it again. We have another fairy tale about another glacier, on a continent far, far away, (too far for you to check on) that is about to suffer a mental breakdown and spill it's guts into oceans, yours and mine. And the fact that no studies have ever found evidence of a glacier actually having had a nervous breakdown and gutspill, has not deterred these intrepid scaremongers from their increasingly shrill speculative excesses. Any natural feature so far from proper scrutiny as this one is certain to merit inclusion within the territorial boundaries of the new, expanding empire of "Bull$hitistan".
Today's "scarenario" is brought to you by the BBC in, "Antarctic glaciers surge to ocean" through the gullible reporting of Martin Redfern. http://news.bbc.co.uk/2/hi/science/nature/7261171.stm And true to form for this entertainment genre, it takes ten paragraphs of spin before we get to any semblance of specific, verifiable facts.
The first piece of infotainment is pure speculation. After the obligatory hint of "new evidence" it leaps onto a giant "IF", and rides off to battle climate demons. "If the trend continues, they say, it could lead to a significant rise in global sea level." This is then massaged through the phobias with, "the "rivers of ice" have surged", and the kind of Churchillian reference to "the weak underbelly of the West Antarctic Ice Sheet" that would enrage every ghost at Gallipolli.
When we finally get to some facts we are told that satellite measurements show three large glaciers have speeded up and the largest one is called the Pine Island Glacier. And being the largest, it is supposedly of the greatest concern. Well, it would really be a crap story if the smallest one was causing most concern now, wouldn't it? I wonder if smaller glaciers are just as prone to mental breakdowns as the big ones?
Meanwhile back at the few facts in this "Beeblical excess", this volume of ice is reported as being, "a couple of kilometres thick, its 30km wide and it's moving at 3.5km per year, so it's putting a lot of ice into the ocean." Note the ambiguity of "a couple" of kilometres. We know that in human terms a "couple" may include an extra person or two on the sly but in this instance we are left to assume that the thickness of this ice is 2.0km, not 1.8km, and not 2.2km in parts. And at 2km thick by 30km wide and 3.5km distance each year we are left to conclude that there must have been 210km3 of ice falling into the ocean this past year.
It takes another ten paragraphs of guff before we are given the most rudimentary map possible, and as usual, no scale. And we are then told that throughout the 1990s the glaciers increased speed at 1% a year. We are not told what the rate of increase was between 2000 and 2006 or indeed, if the speed increased at all. It may well have slowed down prior to 2006 because that is what glaciers do. They have periods of surge followed by periods of relative stasis.
But we did get to hear that the speed in 2007 was 7% faster than what it was in the 1990s, whatever that means. For they were increasing by 1% each year in the 1990s, remember, so which of these ten speeds was used as the benchmark? The first or the last? We know from the guff that Vaughan, Scott and Bingham spent 97 days there and they "also placed recorders linked to the global positioning system (GPS) satellites on the ice to track the glacier's motion, recording its position every 10 seconds."
Now lets see, 3.5km/year is 9.59m/day, 399.6mm/hour, 6.66mm/minute and 1.11mm every 10 seconds. And this tells us that they are going out of their way to try and appear credible because only the most accurate GPS instruments have an error margin less than a metre so hourly records over time would still yield greater accuracy than the "couple of km" in height we were given above.
Working back from the numbers, we find that if 210km3 is 7% faster, then the comparison volume (be it 1999 or 2006) was 196.26km3. And if we assume that 1999 was the comparison year and there was no change from 2000 to 2006 then the discharge volume in 1990 was still 179km3. We are talking about a total increase in discharge of only 31km3/year.
But wait, we are also informed that they, "left a GPS there over winter to see if it is going to continue this trend." Yes, they have extrapolated from about 90 days worth of data and we can be reasonably certain that the 1990s data was obtained without the benefit of onground markers. In fact, the last people in that area before them were back in 1961.
They also inform us that if most of the volume in the Pine Island Glacier were to suddenly melt then global sea levels would rise by 25cm. And as we know that there is 361 million km2 of ocean surface, they are telling us that they think there is more than 90,000km3 of water, and therefore 100,000km3 of ice in the glacier. The problem is that when I try to transpose the area on their rudimentary map onto a decent one with a scale I get an area that is approximately 300km long and about 100km wide. And this 30,000km2 would need to be 3.3km thick to give that volume, not just "a couple" of km.
This would mean that the glacier discharged only 0.21 of 1% of its volume last year, assuming the rate for the 90 days of mid summer measurement was the same for the whole year. It means that the rate of discharge has increased from 0.18 of 1% since 1990. And if there really is 100,000km3 of ice in the glacier and it continues to discharge at the rate of 210km3/year, and assuming there is no new ice deposition at all, then it will take 476 years to go away. At the 1990 rate it would take 558 years. This is quite a bit different to the "nervous breakdown gut spill" scarenario that Scott claims, "might take decades or a century".
But wait, there is much, much more. A quick google of "Pine Island Glacier" suggests that there is quite a bit left unsaid in the BBC report, and some very serious garbled messages to say the least. First, the Antarctic Sun ran an article in the lead up to the above expedition on 22 November 2007 by Editor Peter Rejcek http://antarcticsun.usap.gov/science/contenthandler.cfm?id=1277
The article dealt with the research to be undertaken by the above mentioned team and made reference to the interface of ice with ocean currents. The natural focus of that interface was on the "grounding line", the point at the base of the ice where the bedrock, ice and water intersect. The article stated, "If all goes as planned, work would begin in earnest the next two field seasons to use a hot water drill to bore through the 500-meter-thick ice and lower instruments into the ocean cavity below". Yes, the grounding line is the point, some 35km back from the ice shelf "calving line", where the volume of ice discharge is best measured and in this case the height of that ice column is 500 metres, half a kilometre, NOT "A COUPLE OF KM" as the BBC reported.
We also went to the Scott Polar Research Institute (at Cambridge) site where we found "Inland thinning of Pine Island Glacier, West Antarctica, A.Shepherd, D.J. Wingham, J.A.D. Mansley, H.F.J. Corr, Science, February 2nd, 2001 see
Where we found a neat map showing the region, at the glacial mouth, where the rate of fastest flow was outlined and clearly stated as being only 200 metres per year. It stated that, "The trunk is bounded laterally by the 200 m yr-1 velocity contour, and streamwise by the grounding line (lower black line) located by Rignot (13) and the intersection of the easternmost tributaries, which coincides roughly with a deep bedrock trough (see Fig. 4A). The greatest elevation change is adjacent to the grounding line, and the thinning is concentrated over fast-flowing ice. Changes beyond the region of fast flow were much smaller".
Yes folks, the rate of flow in 2001 was 0.2km/year, not the 3.5km/year as reported by the poor old Beeb-bogans. And it is this flow that has "surged" by 7% to 0.214km/year. One explanation for this is that a classic bit of garbled reporting has taken place that the research team do not appear to have corrected. For when we multiply the 30km cross section by 0.5km depth and 0.214km/year speed we get a total of 3.21km3 of annual ice discharge. And when we divide their 100,000km3 of ice by this 3.21km3 of annual ice discharge we find that it will take 31,152 years for the glacier to depart this mortal coil (give or take an ice age).
And given that annual precipitation and ice deposition in Antarctica ranges from 200mm on the coast to 50mm in the interior, then new ice deposition on the glacier will be some where between 1.5km3 and 6km3 each year. If we use the most conservative figure of 1.5km3 we get a net annual loss of only 1.71km3 and a massive 58,479 years left in the glacier.
It is possible that Scott has rounded the original 3.21km3 up to state the rate of discharge as 3.5km, but meaning 3.5 cubic km, to which the reporter has assumed was the annual speed of discharge. But this slant on the situation would seem naive to experienced climate spin monitors. There is, for example, no evidence in any of the statements made by the team, of a serious commitment to providing verifiable factual information. There is, in contrast, a serious oversupply of speculative opinion and sensational extrapolation. A grumpy old climate sceptic might reflect that the credibility of this body of the teams opinions would not be well served by any exposure to the actual facts on the ground. Rather, those opinions are much better served by the absence of those facts in a context of vagueary. I leave that for others to judge.
But even more curious is the insight into the way the insidious cancer of apocalyptic speculation has taken root in the collective scientific mind. Note that this rapid surge in flow has been attributed to possible volcanic activity under the ice mass. We are informed that an eruption took place some 2,200 years ago so this has a ring of plausibility about it. But lets just hold on, now. This surge in glacial speed may be a product of volcanic lubrication but for the ice discharge to continue for the many, many decades needed to make any dint on the ice mass, it would also need the volcanic activity to continue for just as long. And for any molten lava to continue over a long duration, there must be a capacity for lava to move away from the vent, thus enabling more lava to escape. And once the outer layer of lava has been cooled by either ice or ice water, it solidifies and becomes much harder to move. Lava only moves rapidly when it is ultimately being discharged into freely flowing gas or liquid. But when that discharge is into a cold stream beneath an ice mass, it becomes its own impediment to further lava discharge at the vent. Thus blocking the source of heat, reducing the volume of basal melt water and returning glacial flows to normal.
And even if this was not the case, there are few natural phenomena that are more intermittent than major volcanic activity. Those that are continuous are generally of smaller scale with unimpeded venting. So why would otherwise intelligent people like the research team bother to assume that volcanic activity under the Pine Island Glacier would be persistent enough and large enough to produce a complete glacial collapse? It is the equivalent of extrapolating from the Mt St Helens eruption that Seattle and Vancouver will be buried under lava and ash by 2030. It is an extremely low probability event.
But if you still fear for your waterfront property then, please, give me a call. Maybe we could swap your block for this bridge I have to sell.
27 Feb. 2008