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
@ur momisugly Frank says:
October 10, 2011 at 9:56 am
I love it when you guys are so adamant when you are wrong.
The NSF statement was only wrong in stating that it was potentially significant (it is too small for that), but
it ismay be non-zero, and it isn’t as simple as Archimedes principle.See also Jenkins and Holland (2007):
http://www.agu.org/pubs/crossref/2007/2007GL030784.shtml
But carry on gloating.
There, fixed it. (I read your link, maybe you should).
JJThoms says:
October 10, 2011 at 9:31 am
So, unless I missed something, the experiment as described and pictorialy demonstrated in that paper showed that at that particular concentration of salt water such a large chunk of ice (large, that is, relative to the volume of salt water) will raise the water level to a certain, measurable degree. I find no flaw with that. It’s pretty straightforward. The problem is that it is in no way even close to representing the real world.
My very brief idea of the way the experiment could be greatly improved upon:
1. Take a volume of salt water that represents the water in the oceans and put it in a basin that (somehow) roughly relates to the size and shape of the ocean basins of the world (i.e. cliffs in some areas, marshes and bays in others).
2. Add crushed ice that would be representative of the amount of sea ice (the “average” volume of sea ice over the last 30 years would be a good enough guesstimate in my opinion).
3. Let the ice melt.
4. Measure the difference in the level of water in the basin.
Doing it the way I just described would at least show a more accurate representation of what would actually occur in the real world, though still not perfect. After all, the coastline is not a smooth, vertical glass wall and the varied nature of the coastal topography would allow for more or less encroachment on coastlines at specific locations, if that makes sense. To me, the experiment that was described and shown in that paper is not much better than the CO2 in a bottle experiment done by ManBearPig and Bill Nye, the PseudoScience Guy.
My guess as to the results would be that although there would be some rise, it would be negligible (probably be less than 0.01% of the normal daily tidal changes).
Only 6 1/2 years to figure out it’s insignificant……
I have a hard time believing that the National Science Foundation didn’t know……….
pat says:
October 10, 2011 at 10:05 am
Though I agree that they are way off the mark, it is also true that as it melts at one pole, it freezes at the other. Granted, that may occur at different rates and with different volumes, but whatever those rates are, I’m sure it is worse than we thought…
JJThoms
I suspect you are also missing the important point that sea ice is mostly frozen SEA! – granted, once frozen, some rainfall and snow will settle on it, but in terms of the initial freezing – it is frozen seawater AFAIK. Of course, glacier ice is formed on land and falls into the sea – so is part of the general hydrological cycle. ‘Sea Ice’ per se is largely frozen sea, so in that context archimedes principle still holds.
[youtube http://www.youtube.com/watch?v=YsWXR1_uYaM&w=560&h=315%5D
Seems that floating ice above the surface of the water will have a different effect on the “shape” of earth’s oceans than the floating ice below the surface of the water. The ice above of the surface constitutes a 2nd story for our “house” of ocean water…when it melts, the 1st story must accomadate it by rising. The ice below the surface, once melted, will contract the 1st story because of the difference in densities. Right? Wrong?
I thought Archimedes Principle said that when a body is totally or partially immersed in water, the telephone rings?
@JJ,
The paper assumes the ice is from freshwater and they’re using the wrong salinity percentage as wsbriggs alludes to.
I couldn’t read it all because I was feeling dumber for having read as much as I did.
Yes, there would be slight differences if the water wasn’t exactly the same. The 2.6% is an overestimate because of the reasons listed above. But, just for funnsies…… did you or can you translate how many feet of sea level rise the 2.6% differential would equate to?
Given the recent claims the sea ice is thinner than it ever has been, and the surface of the current ice area is < 5 mill km2, while the earth's water surface is ~ 360 mill km2….. so that's about 1.4% of the surface area…do you think the 2.6% makes any difference? I haven't bothered to look at the estimates of the volume of ice they believe is out there now……. but, I think we'll be ok.
I just had a huge realization. It is normally assumed that ice on land will contribute to sea level rise when it melts because it is being supported by the land and not floating. But then I just realized that the land is not itself resting on a solid object. Under the land is a sea of lava. Therefore, by Archimedes principle, when the ice melts, the land under it will float up in the lava sea and allow the level of the lava under the ocean bed to subside, thus lowering the sea bed and sea level. Actually, the ice melt may contribute about 50% of the sea level rise you would otherwise expect, because not only will the sea bed subside but the land of the continents that was not under ice will also subside, lessening the subsidence of the sea bed and lowering the tide gauges.
There was some poor soul on another blog all worried about Maldives flooding and kids were preparing to be taken as refugees to other islands. She was genuinely concerned for these people.
I did my best to help her by linking a close by “400 miles” monitoring site that showed the current rate of rise was equal to 6″ in about 100 years. The chart also showed that over the last year the sea level had actually dropped.
Reminds me, I didn’t even get a thank you for doing the research. Maybe she wasn’t so concerned…
Mindbuilder says:
October 10, 2011 at 10:30 am
essentially correct. it’s generally called isostatic rebound – but is usually pretty slow!
Lars P says:
October 10, 2011 at 10:07 am ….
ups I got it wrong, shame on me.
What they say is that ice displaces the volume of less water when water is salted. So 1 kg of frozen ice displaces the volume of 1 kg of seawater, which is 970 g water + 30 g salt which occupies the volume of how much sweet water?
The actual rise is obviously insignificant.
WUWT title plus text is simply non scientific:
NSF just now figures out Archimedes’ buoyancy principle
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.
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
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……
I have tried this experiment as stated and with other liquids. Beam, JD, Jameson, etc and I never am able to reach a conclusion as the liquid always vanishes prior to the ice fully melting. Any suggestions?
@Mindbuilder
I seem to recall reading somewhere that this is precisely what happened to land masses as glaciers retreated at the end of the last ice age. all those land based glaciers melting should have raised the sea levels but the land that had been weighed down by all that ice rose up due to being relieved of the weight. I don’t recall whether the net result was a loss or gain in the amount of dry land though.
John says:
October 10, 2011 at 10:26 am
Seems that floating ice above the surface of the water will have a different effect on the “shape” of earth’s oceans than the floating ice below the surface of the water. The ice above of the surface constitutes a 2nd story for our “house” of ocean water…when it melts, the 1st story must accomadate it by rising. The ice below the surface, once melted, will contract the 1st story because of the difference in densities. Right? Wrong?
Completely wrong.
Remember the old rule about the iceberg with seven eighths below the surface? That’s because the ice in an iceberg is seven eighths the density of seawater. As it melts it reverts to the density of seawater so there is no effect. The entire reason ice floats is because water expands as it freezes because the water molecule crystal lattice that is called ice takes up more space than unfrozen mobile molecules. This expansion starts a few degrees before freezing as the clumps of crystal lattice start forming. This is why ice forms on top of a body of water.
Maurizio Morabito (omnologos) says:
October 10, 2011 at 9:26 am
Talking of buoyancy, as silly question for the day, with CO2′s molecular weight around 44 and the air’s 28 shouldn’t even well-mixed CO2 have a rather higher concentration near the ground?
Depends of the mixing speed where the sources and sinks are. Over the oceans, the mixing speed is larger than the speed at which the oceans release or absorb CO2, thus there is little difference between the equator and the poles over the oceans, neither from sealevel to about the stratosphere. Only huge changes like seasonal absorption and release by vegetation gives moderate differences between altitudes and latitudes. The largest differences are over land, where most point sources and fast sinks are situated. For semi-rural places, with little wind the CO2 levels increase at night and decrease during the day, when the sun starts the photosynthesis.
Here an overview of af a few days of CO2 levels at four “baseline” stations from the NH (Barrow at sealevel, Mauna Loa at 3,400 m) and the SH (Samoa at sealevel and South Pole at 3,000 m) and Giessen (Germany, semi-rural):
http://www.ferdinand-engelbeen.be/klimaat/klim_img/giessen_background.jpg
The differences between near ground over land and the “background” CO2 levels are decreasing with height and wind speed. Over 500 m over land, the air is at background CO2 level, as flight measurements show:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/inversion_co2.jpg
Maurizio Morabito (omnologos) says:
October 10, 2011 at 9:26 am
“Talking of buoyancy, as silly question for the day, with CO2′s molecular weight around 44 and the air’s 28 shouldn’t even well-mixed CO2 have a rather higher concentration near the ground? I mean, the concentration profile of CO2 according to height cannot be the same as the one for oxygen, can it?”
I have been asking this question, and similar questions about our empirical knowledge of CO2 concentrations, for years. The only answer you will get from the Warmista is that CO2 is well-mixed. They will not address any question about measurements, experiments, or anything similar. In other words, the answers you get are typical Warmista answers.
Now if we can only get them to admit the seas have stopped rising,
even according to their biased measurements.
It’s always nice to see a new troll. The old ones get boring.
Aah, but the part of the ice that is sticking out of the water is farther away from the axis of the earth, and therefore subject to a greater centrifugal force, which counteracts the gravity! Therefore, the volume of water displaced by the ice IS less than the volume of the water it will turn into.
At 500 km from the north pole, this effect amounts to a fractional volume increase due to thawing of approximately 0.000,000,000,000,04.
Now, this number seems small. On the other hand, if we now use this number to calculate how much sea ice must already have melted in order to cause the sea level rise that did happen over the last decades – it turns out that it is definitely worse than we thought!
JJThoms says:
October 10, 2011 at 10:42 am
“The actual rise is obviously insignificant.
WUWT title plus text is simply non scientific:”
“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”
So you’re saying the correction by the NSF is wrong? And they were right before?
The experiment that he showed was meaningless as it is not relevant. In the Arctic the ice forms from the sea water. As it does it gives up salt into the sea. When it melts it remixes with the salt. A zero sum equation. If he had done this in his beaker you should see the level drop and then rise again as the ice melts.
DirkH: No, the uncorrected NSF page is not right if the actual rise is insignificant, since it claims “significant effects for coastal cities and towns”.