Just like Archimedes discovered millennia ago, it is well known today that the Arctic ice cap displaces it’s own weight in the water so that when it melts it will not cause a rise in global sea level.
Surprisingly, the National Science Foundation has just figured this out (thanks to someone complaining about it) and has issued a correction to their sea ice page.
The error was first pointed out by commenter Steven Skinner on WUWT on March 25th 2010, who wrote:
The NSF, the U.S. Office of Naval Research, and the Japanese government cooperated in funding a research project called SHEBA (Surface Heat Budget of the Arctic) back in 1997. Considering the big names in funding I was surprised they allowed the conclusion in the last sentence past scientific proof reading before publication. The bit from ‘melting sea ice…’
It’s fixed now, see the BEFORE and AFTER.
WUWT reader Dave Burton, who called NSF on the error and asked for a correction writes in an email to them:
Since the error was on your site for over 6.5 years, misleading readers into believing that melting sea ice contributes to coastal sea level rise, I think it is important that you identify the error on your site, with a footnote which explains what was wrong with it.
I always wondered why I’d get the occasional angry email claiming melting Arctic sea ice would raise sea levels dramatically and “why don’t you get it?” …to which I’d reply “look up the principle of buoyancy”. Now I know.
Further suggested reading: 10 Scientific Laws and Theories You Really Should Know
@Kev-in-Uk – Slow? Unless the lava of the lava sea is so viscous as to be nearly rigid, the rebound would be immediate. That stuff coming out of volcanoes is not anywhere near that viscous. The isostatic rebound might appear slow in the area close to the melt because of the fair rigidity of the crust over short distances, but at some distance away, the effect would be immediate.
But I also realize now that the rise and fall of the lava sea would be proportionately less than the height of the ice melt due to the lava sea having a higher density than the ice and water. So, for example, if 4 meters of ice on top of Antarctica melted, and the lava sea is four times denser than the ice, then the lava sea under Antarctica would only rise 1 meter. The subsidence under the sea bed would also be proportionately less. Cut this in half again, accounting for the subsidence of the land of the continents with tide gauges not under the ice, and it doesn’t appear this effect will do much to save us from the sea level rise of melting land ice.
FrankSW says:
October 10, 2011 at 9:49 am
You can see the effect with simple experiment that can be carried out at home, just pour a gin and tonic, add ice and watch……
———————
Frank, I tried that and found as the ice melted the glass got emptier. Must mean something.
The maximum density of water is about 4 degrees C. Cooling water at 4 degrees causes expansion but melting it and warming it to 4 degrees C actually causes contraction. I would suspect that is the more common in the arctic melt to go from zero to maybe 4 degrees than the other way around. I doubt it gets much warmer. The tiny correction that Frank suggests is probably that melting sea ice actually lowers sea level a tiny bit but that is just an educated guess.
Mindbuilder says:
October 10, 2011 at 11:22 am
Yes – SLOW ! – just think of a super viscous liquid. an analogy might be glass which is a supercooled liquid and think of very old glass panes, they are thicker at the bottom than the top due to gradual ‘slumping’ downwards due to gravity over many years.
Isostatic pressure downwards displaces the viscous mantle – which then has to work its way back. another analogy might be a jug of treacle. stick your finger in, then pull it out – the depression your finger made takes some time to fill back up – it is not instantaneous. same principle – just much much much slower!
Much has been made of the reduction in multi-year ice in the Arctic. The ice that is present at any one time is a snap-shot of the hydrological cycle. Averaged out over a few years the salinity will be effectively constant and therefore Archimedes rules.
“I always wondered why I’d get the occasional angry email claiming melting Arctic sea ice would raise sea levels dramatically and “why don’t you get it?””
Exactly why dont you get it? This is/was the consensus view of the NSF and peer reviewed by many top scientists.
Dr Roy Spencer “oh, and if you read his new paper, he seems to have a typo early in the paper…he claims we do NOT believe cloud radiative forcing causes temperature change. Of course, the opposite is the case. I have no idea how such a statement could have made it through 2 peer reviews.”
http://www.drroyspencer.com/2011/10/ive-looked-at-clouds-from-both-sides-now-and-before/
It aint a typo – its a fact if its been peer reviewed.
Hmm, this could be a bit embarrassing for the Team. I’ve taken the liberty of drafting a quick statement that they could use should they get any press inquiries:
“Archimedes is not a peer-reviewed climate scientists and therefore is unqualified on this subject. Once again, the press is reminded that not all opinions should be given equal weight. There is consensus in the peer reviewed literature that the unprecedented melting of floating ice will lead to the death of 342,786,934.3 people by June 6th, 2027. These manufactured ‘controversies’ like we see from WUWT and other denialist screeds are the result of deliberate distortions by Big Tobacco and Big Oil who seek to distract attention from the fact that variations in surface temperature have been shown to be entirely caused by humans”
This is, of course, for floating sea ice. What about sea ice that is bottomed out and resting upon the ocean floor? Seems like it could add to sea level if melted. Does anyone know how much sea ice is in shallow enough situations to do this? Cannot float if the water is too shallow for the ice to displace its own weight. Of course it’s getting colder, not warmer, so why worry?
Six years! It took them six years to notice that… and someone had to tell them: pathetic.
FD
NSF = non-sufficient facts.
I always thought that sea ice is formed by sea-water freezing below and snow compression above. So the sea ice will have already have some salt content.
Further, doesn’t most of the Arctic sea ice melt every year anyway, from a peak of 15 million km^2 to under 5 million km^2? Why doesn’t sea level rise every summer? Or is NSF talking about some other Arctic sea ice?
Me thinks they got caught crying wolf.
@JJThoms says:
“Sea Ice (even created from the ocean) is much less salty than sea water. The density of sea water is greater than the ice. The ice will (according to archimedes) displace its own WEIGHT. The volume of sea water displaced will be less than the VOLUME of ice displacing it. QED”
JJ Thoms you have figured out that the “The volume of sea water displaced will be less than the VOLUME of ice displacing it.” ???
You maybe weak in English but it seems in logic also. If ice displaces a certain volume of water, that is the volume of water it displaces.
Scientists that can do science do do science. Those that can’t do science teach science and those that can’t teach science become NSF (NCSE, NAS, AAAS, NSTA, IPCC, etc) staff.
BravoZulu says:
October 10, 2011 at 11:27 am
“The maximum density of water is about 4 degrees C.”
That’s correct but the maximum density of SEAwater is -2C. Unlike fresh water, salt water keeps getting denser right up to the point it freezes.
http://en.wikipedia.org/wiki/Properties_of_water#Density_of_water_and_ice
he density of water is dependent on the dissolved salt content as well as the temperature of the water. Ice still floats in the oceans, otherwise they would freeze from the bottom up. However, the salt content of oceans lowers the freezing point by about 2 °C (see following paragraph for explanation) and lowers the temperature of the density maximum of water to the freezing point. This is why, in ocean water, the downward convection of colder water is not blocked by an expansion of water as it becomes colder near the freezing point.
Don’t feel bad, it’s a VERY common mistake and one I have to correct in these pages fairly often.
Ian W says:
October 10, 2011 at 10:52 am
“This expansion starts a few degrees before freezing as the clumps of crystal lattice start forming.”
Not in seawater. The salt content reduces the freezing temperature by about 2C and also causes the density to keep on increasing right up to the freezing point. It’s amazing how many people don’t know about the strange maximum density point of fresh water but don’t know the less surprising fact that seawater behaves in the intiutive way,
oops that should be “amazing how many people DO know about the strange maximum density point of fresh water” in my previous missive
If all the Arctic sea ice (27,800 km^3 from PIOMAS) melted and there was a 2.6% difference between the salty sea and the fresh water sea ice the world’s oceans would rise by 2 mm. Interestingly, annual sea level should rise by about 1.2 mm anyway so the difference would be another 0.8 mm.
Chuck Nolan says:
October 10, 2011 at 11:23 am
FrankSW says:
October 10, 2011 at 9:49 am
To be a truly scientific experiment you need to use a second control glass of ice/whiskey that is not randomly taste tested to evaluate the process of the dilution/evaporation of the alcohol. (refilling the tasted non control glass as needed to double check the mixing potential of the solution is sometimes required.)
This article on sea ice by the NSF is hopelessly out of date and poorly written.
It not just confuses sea ice with ice sheets (even after the correction on sea level) but it fails to mention a tremendous amount of new information obtaines and developments that happened since the early 2000’s when this piece was written.
A complete re-write of this article would be appropriate.
JC says:
October 10, 2011 at 11:18 am
Right! If I had to give out the research funding, I would give it to you and no one else.
Some have claimed that there is a finite rise in sea level when sea ice melts.
I can only assume that there is a finite but equal drop in sea level when it freezes.
Or does my logic fail me?
Annual sea level should also fall by 1.2 mm over the winter due to Arctic sea ice increasing. The NSF should have written:
“In addition to altering salinity, melting sea ice also raises worldwide sea levels by up to 2 mm, with potentially significant effects for coastal cities and towns.”
That would have quantified their alarmism.
You can always find the nigglers who can point to a physics experiment that says the sealevel goes up. But lets do the experiment properly and see what we get: take seawater in a beaker and measure, freeze a layer on the surface and measure, finally thaw it out again and measure. If you get rising levels this way, we can solve th world’s water problems.
mkelly says:
October 10, 2011 at 10:43 am
I have a suggestion. Piss on the ice cubes to fill the glass. Presumably that won’t disappear before the ice melts in the manner of the others.
This is shocking for a “Science” site. Its primary level science. Obviously none of these guys had a look at their scotch on the rocks before and after (as long as ice was floating from the start of the drink) LOL
The net loss of intelligence from the effort to sustain AGW is alarming.