Collectively the average annual loss of ice from the Greenlandic and Antarctic ice-caps is about 770 billion tons per year. Dispersed across the 510 million square kilometres of oceans, this should cause the average sea-surface level to increase by 1.5mm per year. And indeed, this is the amount that real-world measurements show.
Coupled with this is the thermal expansion of the oceans. Water has the almost unique property of being densest at 4°C (i.e. not freezing point), in the polar regions where the oceans are warming this is causing thermal contraction but this is far outweighed by expansion in the rest of the world. The net effect is sea-levels are rising by 1.6mm per year. Again, something that can be both calculated on paper and observed in the real world.
Finally there’s a small contribution caused by isostatic or post-glacial rebound. This is adding a further 0.1mm a year to sea-levels. This value can be considered a constant (it’s changed little in thousands of years), glacial meltwater and thermal expansion are variables.
Collectively these three components are causing sea-levels to rise by 3.2mm per year. As is normal, this is not a consistent figure but is the long-term global trend. Some years it’s less, some year’s it’s more, in some parts of the world SSL is decreasing slightly, in others it’s rising 10 times as fast.
Also, as is the norm, these figures are based on overall averages and do take account of the fact that glacial mass balance is increasing in some parts of Greenland and Antarctica. You’ll often hear the deniers mention this but of course, what they don’t tell you is that these few places are the exception to the rule.
Given that equilibrium between oceans and atmosphere takes somewhere between 4,000 and 10,000 years to be achieved, we know that there is going to continue to be significant heat exchange far into the future; the net effect of the exchange being a warming of the oceans. Whilst the sea-surface layer is some 2.9°C warmer than the atmosphere, the exchange occurs due to the upwelling, overturning and general mixing of the colder sub-SSL water.
The latest Gravity Recovery And Climate Experiment data suggest that recent estimates of sea-level rises have been underestimated and that the probable sea-level rise by the end of the century will be between 800mm and 1400mm; it had previously been estimated at between 190mm and 590mm. Other research provides different values with the modals being in the 500mm to 1000mm range.
The notion of catastrophic sea-level rises and New York being underwater in the near future are yet more examples of the moronic lies from the intellectually deficient and honesty bereft deniers. As with just about everything from the deniers, these claims belong in the bin. Yes, sea-levels are rising; no, we’re not going to be underwater in the future.
As for the melting of the Arctic sea-ice – it’s irrelevant because it’s floating and therefore already displacing it’s own mass of water.
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RE: YOUR ADDED DETAILS
The Uni of Colorado don’t have GIA at 0.3mm a year, they use minus 0.3mm a year. And their calculations don’t show 2.8mm a year but 3.4mm a year, which after deducting for GIA gives 3.1mm a year, and since 2011 they’ve been using 3.2mm a year – exactly the same figure as mine.
You claim the figure is adjusted upward but you’re wrong once again, the top end figure is 3.6mm a year, bottom end is 2.8mm, 3.2mm is the mean.
As for the links – did you read them, I guess not. They’re talking about what might happen over the course of hundreds of years. For example (from 2nd link) “Such a hike in temperature could lead to a rise in sea levels of between 13 to 20ft (4 to 6 m) over hundreds of years as the ice sheets melt.” Let’s say 500 years, that means 1 metre per year; which ties in with the other links that mention figures of up to a metre in 100 years. All of which relate to the figures I gave in my original answer.
Let’s compare this to the deniers. Sagebrush for example claims that Manhattan was supposed to be under water by 1999. The only place he would have got such a notion from is fantasy land or a denier website (which is essentially the same thing). Of course, he can’t back up this claim, but that’s precisely what rational people have come to expect from the irrational deniers.
Here’s something to consider. The Thames Barrier was constructed to protect London from flooding, it’s basically a dam that can be raised into place to cut London off from the sea. In it’s first 10 years of operation (1982 to 1991) it had to be closed 10 times to protect London, in the last decade it’s needed to be closed 75 times. Why do you think this might be, if not for the fact that sea-levels are rising?
http://www.environment-agency.gov.uk/static/documents/Leisure/Long_Summary_of_Flood_Defence_Closures.pdf