From a University of Leeds press release, comes this scary headline that seems to be picked up by the MSM. A Google search yields 16,400 hits on the title below.
Melting icebergs causing sea level rise
(Note: Be sure to see the reality punch line at the end of the article)
Scientists have discovered that changes in the amount of ice floating in the polar oceans are causing sea levels to rise.
The research, published this week in Geophysical Research Letters, is the first assessment of how quickly floating ice is being lost today.
According to Archimedes’ principle, any floating object displaces its own weight of fluid. For example, an ice cube in a glass of water does not cause the glass to overflow as it melts.
But because sea water is warmer and more salty than floating ice, changes in the amount of this ice are having an effect on global sea levels.
The loss of floating ice is equivalent to 1.5 million Titanic-sized icebergs each year. However, the study shows that spread across the global oceans, recent losses of floating ice amount to a sea level rise of just 49 micrometers per year – about a hair’s breadth.
According to lead author Professor Andrew Shepherd, of the University of Leeds, it would be unwise to discount this signal. “Over recent decades there have been dramatic reductions in the quantity of Earth’s floating ice, including collapses of Antarctic ice shelves and the retreat of Arctic sea ice,” said Prof Shepherd.
“These changes have had major impacts on regional climate and, because oceans are expected to warm considerably over the course of the 21st century, the melting of floating ice should be considered in future assessments of sea level rise.”
Professor Shepherd and his team used a combination of satellite observations and a computer model to make their assessment. They looked at changes in the area and thickness of sea ice and ice shelves, and found that the overall signal amounts to a 742 cubic kilometres per year reduction in the volume of floating.
Because of differences in the density and temperature of ice and sea water, the net effect is to increase sea level by 2.6% of this volume, equivalent to 49 micrometers per year spread across the global oceans.
The greatest losses were due to the rapid retreat of Arctic Sea ice and to the collapse and thinning of ice shelves at the Antarctic Peninsula and in the Amundsen Sea.
For more information
To arrange an interview with Prof Andy Shepherd, contact Hannah Isom in the University of Leeds press office on 0113 343 4031 or email h.isom@leeds.ac.uk
Notes to editors
“Recent loss of floating ice and the consequent sea level contribution” by Andrew Shepherd, Duncan Wingham, David Wallis, Katharine Giles, Seymour Laxon, and Aud Venke Sundal is published this week in Geophysical Research Letters (doi:10.1029/2010GL042496).
ICE SHELVES are thick, floating platforms of ice that form where a glacier or ice sheet flows down to a coastline and onto the ocean surface. Ice shelves are found mainly in Antarctica , and range from about 100 to 1000 metres in thickness.
SEA ICE is formed on the surface of sea water as the ocean freezes, and is typically less than 3 metres in thickness. It is found extensively in both the Arctic and Antarctic regions, and it’s extent varies considerably over the seasons.
This study was funded by the UK National Centre for Earth Observation and the Philip Leverhulme Trust.
==========================================
OK here’s the reality punch line:
Assuming their theory of 49 micrometers per year rise (this conversion equals 0.0019 inch or 0.00016 feet ) due to the differences is salty and fresh water holds true, then we can assess the threat level.
At this rate, to see an inch of sea level rise from melting icebergs we’d need:
1 inch/0.0019 inch/yr = 526 years
Yeah, I’m worried about that.
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
Stephen Skinner says: May 1, 2010 at 7:02 am
“Again. The ice will displace it’s own weight so it doesn’t matter if temperature or density changes as this will be reflected in how much ice sticks up above sea level, which will change accordingly.”
—
You know, when I first read this article this morning I was saying the same thing you are saying. Archimedes wrong in this case, poppy cock! But I love physics and I just had to test this out. These are the weird things that make physics enjoyable and fascinating.
So I went to wiki and got the densities of ice, water, and sea-water. Set up a thought experiment with 10x10x10 cm cube beaker (1000 ml) with a 500 cm3 (or ml) cube of ice in it and then fill it to the brim with sea-water. Get that in your mind. The ice sticks ~10% above the rim of the beaker of coarse.
The rest is rather easy to calculate, but I will be darned, he is correct. The volume of the melted ice, even though it sticks out of the beaker will be larger than the “hole” that the floating ice creates and occupies in the sea water. Amazing. I spent a good bit of today checking and double checking the calculations. I kept coming up with 2.5%, not 2.6% difference. Close enough.
Now that’s interesting to me. If he’s right (and now me), and it appears it is so, and it’s proper physics, then he deserves at least a nod for his honesty and foresight. Here is some unexpected science. We have seen so many things coming out of the AGW camp that are blatantly distorted, manufactured, and manipulated in science and physics that is hard to believe that any thing coming out from that side is true. But this one does appear so.
But put it in perspective, I also calculated base on that 2.5-2.6% difference and the effect is TINY. As I stated above, ALL of sea ice in the entire world if melted at once would only raise the oceans 7 millimeters, not centimeters. That’s about the width of a pencil or the diameter of a pea. If you were standing at sea level the rise would barely cover the soles of your shoes. Now that’s comical! How do you make a scare story from that?
But if your interested in a quirk about Archimedes principle, here are the three densities to compute it yourself, 0.9167 for ice, 1.0 for water, and 1.025 for sea water all in g/ml (same as g/cm3). The key is the volumes, not the mass that does this since water expands when frozen and salt water is ~2.5% denser than water, so Archimedes was still right all along, he was only measuring mass.
Since no one has taken up my challenge to look at physics I’ll have to do it myself.
We can assume that the ice would melt by cooling the sea water
To melt ice requires 334 kJ/kg. According to the paper 742 km3 of ice are melting each year. This therefore requires
334 kJ/kg * 742 km3 * 10^12 kg/km3 = 2.48 * E17 kJ.
The volume of the ocean is 1.37 E6 so its temperature would drop by:
2.48 E17 kJ / ( 4.186 kJ/C/kg * 1.37 E6 km3 * 1 E12 kg/km3 ) = 0.0435 C.
The coefficient of thermal expansion of water is 207 E-6. So the volume of the ocean would reduce by:
0.0435 C * 207 E-6 /C * 1.36 E6 km3 = 12.3 km3.
The surface area of the ocean is 316 E6 km2. So the fall (note fall not rise) in ocean level would be:
12.3 km3 / 316 E6 km2 *1E9 mm/km = 38.8 mm. (this is per year)
Which is almost three orders of magnitude larger than the 49 micrometers due to different densities.
It seems a big difference so can someone please check.
@Steve Keohane (May 1, 2010 at 6:47 am)
The side-by-side pictures at http://i44.tinypic.com/2vrwuae.jpg are at slightly different scales, so transferring a template from one image to another must be done with allowance for this change. If you compare the number of pixels between the top or bottom of the image, and the edge of the earth, it’s clear that there is less margin area in the later (2010) image.
A likely cause of this effect would be a reduction in satellite altitude between the image capture times. Other things being equal, at a lower altitude the earth will subtend more pixels in the image.
Smokey says:
April 30, 2010 at 8:59 pm
May have been posted before, but well worth posting again:
http://www.blip.tv/file/3539174
Thanks, Smokey. I’ll be sending this link along to people I know.
For those who haven’t checked it out, it’s segments by Pat Michaels and Joe D’Aleo in a congressional briefing on Climategate that occurred 2 weeks ago. D’Aleo’s a little hard to follow, but if you stick with it, it’s worth it.
FWIW, I emailed Hannah Isom in the University of Leeds press office asking if the “Recent loss of floating ice and the consequent sea level contribution” report is some kind of farce published to show how silly some research can get. An auto-reply says she’s out of the office until Tuesday. I suspect I’ll get no reply from Hannah herself, but if I do and it still seems relevant, I’ll post it in Tips and Notes.
I’m reminded of a joke:
“Earth and Venus may collide in 5 billion years. We must act NOW!!!!”
I remember how they say religion only makes people afraid. Science should not go that away. The article sounds more like a satire.
Microns or whatever; as a famous tennis player once said ‘You cannot be serious’.
The obvious fix for sea-level rise is to call Exxon-Mobil and Shell to the rescue. A few waterflood projects where they take water from the ocean to pump into oil formations will be good for oil production and keep those nasty waves at bay. There! Problem solved.
RE: Climate Craziness —
I see that a notorious Wikipedia censor has just written a number of articles critical of Dr. Judith Curry and her effort to bridge the gap between both sides on the AGW issue.
Nice set of graphics Steve Keohane. I had came to the same conclusion just based on eyeballing the side-by-side pictures awhile ago, however, your work shows the changes much better.
Any idea how much this affects the total ice area?
Ron Manley says:
May 1, 2010 at 8:31 am
Your right, it is off by exactly 3 orders, in the bottom equation mm/km is 1e6, not 1e9.
Sean Peake says:
May 1, 2010 at 12:55 am
Way, way OT
Hi Sean – Thanks very much for that! I am familar with some of that but some I’ve never seen before. But we really do need to get in direct contact as I may be able to clarify some things about them which you would probably like to know before going to print.
Did you see anything in his daily journals?
In the meantime I’m going to think of some kind of Thompson-related code for getting you my email address. For starters, I have a yahoo.com adress for net related things. It has a seven character prefix. Now to figure out how to communicate that part.
And thanks in advance to Anthony or mod for allowing this way, way OT chat.
Gail Combs says:
May 1, 2010 at 6:47 am
Dartmoor Resident says:
May 1, 2010 at 5:06 am
Somewhat OT, but can someone help me, please, with figures for polar bear numbers.
__________________________________________________________________
Try this article: http://wattsupwiththat.com/2009/09/12/oh-no-not-this-rubbish-again-recent-projections-suggest-polar-bears-could-be-extinct-within-70-years/
———–
Had not seen this article before. Sums things up very well!
Sean Peake – Do you have Glover 1962 handy?
Insane that funding would be available for such nonsense. I had to come here to find sanity after trying to bring some empirical truths to the comment section of an AL Gore article in the HUff Post. They stopped posting my comments after a while even though I violated no terms of service. I guess it’s bad form to provide facts. They couldn’t dismiss me as a right wing wacko.
Pete – I guess that means you didn’t earn your little ‘Community Moderator’ badge for deleting your quota of inconvenient/heretical comments there? I looked at that site recently and couldn’t believe that set up. Chairman Mao’s block snitches – or is it ‘ideological peer review’ – on the net! And I noticed that even some of the regulars there (judging by their other little badges) were disgusted by that new Orwellian approach. Its a sick joke… unless you are a big fan of groupthink. But I guess that group will soon have that place all to themselves, and can then claim that ‘the consensus agrees that [whatever]”
No loss really. The level of discourse there is, well, … hmmm… how to say it nicely… oh, never mind.
Increased evaporation in a warmer world could offset the 49 micrometers. If not, we could carry battery-operated hairdryers with us to dry our way to safety should we get trapped by a 49 micrometer flooding. Charged with wind power generated electricity; better safe than sorry.
NSIDC shows we are heading for the great sea ice barrier again. Maybe in early May we will be above the ’79-’00 average for sea ice extent.
Did anybody else notice last months summary – NSIDC says a “cold snap” caused the late peak in sea ice extent but when i looked at temps above 80 degrees north it looked warmer in 2010 than it did in 2009 when ice peaked?
http://ocean.dmi.dk/arctic/meant80n.uk.php
I would have thought atmospheric and oceanic circulation patterns are the factor that has a biggest year to year impact on sea ice extent. It is well below freezing temperature in the arctic every year. What is NSIDC on about in the March summary?
A lot of people are claiming that since any floating object will displace it’s own weight of the medium it is floating in, if ice melts it will make no difference. That has been known for a while.
That is true if ice is floating in pure water, since the mass of water displaced will be the exact same volume as the water it becomes. If the ice is floating in a heavier medium, such as salt water, the volume of water it melts into is more than the volume of sea water it displaced as ice.
So the water will rise. The point being made here is not that, however, but that the rise is almost impossible to measure, and laughably insignificant.
Apols if this has been pointed out already.
Charles Higley, surely you don’t believe that Professor Andrew Shepherd would write an article with such an error of basic physics. He would be a laughing stock if he did so and his PhD would be ripped off him.
No, I believe the Professor is right, except for the scary headline. The headline should read “Melting icebergs causing infinitesimal sea level rise, then they refreeze”.
But why are we arguing about theory? Let’s do some real science and do an experiment. I hope to show the results of my experiment in a day or so.
A slight problem with my experiment:- I wanted to freeze salt water to get the expected mostly-water ice cube, but the salt water has all frozen rather nicely. The level has stayed the same before and after the freezing and after the thawing.
The experiment has already been done here:
http://www.physorg.com/news5619.html
but I wanted to see the level before the ice cube was formed.
Problems with that experiment: – the scale is upside down and zero is not at the bottom and the photos were taken from different angles.
If “small comets” contribution to the earth;s ecosystem is true, the science not being settled yet, then there is nothing that can stop a sea level rise.
I can imagine that, considering the implications, the the “science” will never be settled.
HaroldW says:May 1, 2010 at 8:35 am@Steve Keohane (May 1, 2010 at 6:47 am)
The side-by-side pictures at http://i44.tinypic.com/2vrwuae.jpg are at slightly different scales, so transferring a template from one image to another must be done with allowance for this change. Precisely, as I noted I scaled the outline from the first image to the diameter of the second.
A likely cause of this effect would be a reduction in satellite altitude between the image capture times. Other things being equal, at a lower altitude the earth will subtend more pixels in the image. A reduction in altitude would increase the relative size of the center of the image, the arctic, rather than reduce the arctic relative to the overall diameter as we see here.
Richard M says:May 1, 2010 at 10:32 am Nice set of graphics Steve Keohane. I had came to the same conclusion just based on eyeballing the side-by-side pictures awhile ago, however, your work shows the changes much better.
Any idea how much this affects the total ice area? Without spending a few hours separating colors and getting a pixel count, my guess is it is on the order of ((.5-1.0) x 10^6) Km^2. I have no idea what they are trying to do fiddling with their representation.
If they are trying to make it visually clearer, why make the earth bigger with a smaller arctic, the inverse would be more pragmatic. While I do not understand the intent, there has to be a reason for the format changes in 2004 and 2010. I could see in 2004 where a better discernment between ice and snow could have led to a reduction in sea area counted. However, if true, then the past measurements were too high, and the current bar for mean/normal ice is too high, and the past measurements should have been reduced. The distribution of ice anomalies for the arctic is not a ‘normal’ distribution. It is much more difficult to get positive anomalies because the sea is basically landlocked.
Al Gored says:
May 1, 2010 at 1:07 pm
Sean Peake – Do you have Glover 1962 handy?
Not at the moment. Why?
Thank you to those who gave me some leads on polar bear numbers (see comment above). I have now found that the 2009 figures for declining sub-populations are given in the press release of the IUCN/SSC Polar Bear Specialist Group meeting prior to Copenhagen last year. I note that this is the group that barred Dr Mitchell Taylor (who said all but 2 of the 19 sub-populations of polar bears were increasing or at optimum numbers) because his views “running counter to human-induced climate change are extremely unhelpful”!
This is something that IMHO should NEVER happen whoever is correct about the numbers.
Al Gored, try to reach me thru LinkedIn or FB. I’m in Toronto