Greenland 'lurched upward' in 2010 as 100bn tons of ice melted
Maybe not time to panic just yet, though
Parts of southern Greenland apparently lurched upwards by as much as 20mm as glaciers melted and ran off into the sea during 2010, according to scientists. It's thought that as much as 100 billion tons more ice than usual may have vanished from the island's ice sheet that year.
Professor Michael Bevis outlined his findings in a presentation at a conference in San Francisco on Friday. Bevis is lead boffin in charge of a network of groundbased GPS stations placed on bedrock outcrops around the Greenland coast, which were set up to measure rises in the rock as the weight of ice atop it diminishes. The stations were set up when gravity-measuring satellite measurements appeared to show colossal rates of ice loss from Greenland, in the range of 300 billion tons annually.
However the stations showed that the initial satellite calculations had failed to properly estimate the bedrock's rebound, and in fact scientists now think that losses from Greenland are probably more in the range of 100 billion tonnes a year, which might cause a worldwide sea level rise in the order of a quarter of a millimetre annually. Prof Bevis's possible extra 100 billion tonnes could thus mean that an extra quarter-mm occurred from Greenland in 2010.
“Really, there is no other explanation," he argues. "The uplift anomaly correlates with maps of the 2010 melting day anomaly. In locations where there were many extra days of melting in 2010, the uplift anomaly is highest.”
This doesn't seem to mean anything very significant for sea levels globally, however. Throughout the 20th century (about as long as consistent records have been kept) sea levels rose slowly and steadily at around 1.7mm each year, and they have been rising for tens of thousands of years since the last ice age. Like world temperatures, sea levels vary a lot year to year, so they must be measured over a long period to detect any trend.
Various global-warming models and predictions suggest that sea-level rise might accelerate massively in a runaway positive feedback loop if global temperatures climb, and so become a major problem - probably the main reason to worry about global warming, if such massive accelerations in the rate of rise actually occur. However the warming seen in the latter half of the 20th century in fact produced no such acceleration. Indeed recent research indicates that the normal rise of the seas may be slowing down somewhat. Even the reliably alarmist IPCC acknowledges that "no long-term acceleration of sea level has been identified using 20th-century data alone".
Against such a background a possible extra quarter-mm of sea level rise in 2010 doesn't mean a whole lot, then. But a major land mass surging upwards (well, parts of it - "stations in the North of Greenland barely moved at all", says Bevis) as gigatons of ice runs off into the sea makes for a good exciting press release, anyway. ®
Well, it's the climate researcher's own data that showed that previous estimates of volume of ice melt were 3 X the actual melt.
I can only speak for myself not for el Reg, and I do believe that the earth is warming and that human activity is to some extent responsible. I also believe that the extent of our responsibilty is less than it is made out to be, that the earth will be just fine if it warms by a couple of degrees, and that extreme environmentalists / scaremongering press / politicians / NGOs routinely emphasise worst-case scenarios and apocalyptic visions over the more likely middle-of-the-road scenarios. I also know enough about computer modelling to know that when modelling highly complicated systems, some parts of which are not properly understood, predictions 10 or 20 years into the future are suspect (let alone 50 or 100 years).
I get enough doom and gloom from the rest of the press combined, and while I know that el Reg pull a bit too much towards scepticism, I am thankful to them for publicising 'out-of-the-mainstream' articles and ideas that would not be published in most mainstream media
Whether global warmining exists or not....
...that's a metric fuckton of ice.
Nyergh... must comment
'The Earth is a big molten ball with scum floating on it, some parts thickier than others, as slow magma currents cause it to crinkle, not unlike the skin on boiled milk.'
As S-waves show, the Mantle is solid. If you drill a hole down through the Crust from almost anywhere on the Earth's surface the first liquid you will hit is in the Outer Core - and then you'll hit a geyser of molten iron.
It's much better to think of the Earth as being similar to a cold Mars Bar. The outside chocolate shell (the Crust) is brittle, below that is a caramel which is technically solid yet highly plastic layer (the Asthenosphere), below that is a solid layer of fudge which is still plastic (the Mantle proper). Bend the Mars Bar slowly and the Crust cracks, but the Asthenosphere and Mantle bend gradually. Hit it hard and they fracture.
Likewise the Mantle undergoes flow over the long term, but remains entirely solid.
Where this theory breaks down is that the Earth is much less delicious than a Mars Bar.
If you really want to see isostatic rebound in action, drive along Route 1 in Southern Iceland between Hveragerði and Vík í Mýrdal. The enormous cliffs on the left of the car are the old sea cliffs from about 10kya; the strip of land you're driving on is the old beach and the sea is anything up to 10km away on the right. Towards Reykjavik the calculations are that rebounds were anything up to 7cm PER YEAR in the immediate postglacial period which would put them amongst the fastest known.