The NSF Corrects an “Error” in Error.
The NSF, after receiving an email from a concerned citizen, recently made a correction to a statement that had been on their website for several years. Unfortunately, the NSF ought to know better than to allow a web site administrator to overrule the findings of qualified scientists on the say so of a lay commentator.
At issue is a comment on an NSF page titled “The Importance of Sea Ice”. The page discusses the findings of two expeditions relating to changes in arctic conditions over a forty year period. Originally, the page contained the following paragraph(1):
“One unexpected finding concerned the salinity of the water. When the scientists first arrived at the Arctic ice pack in October 1997, they discovered that the water was much fresher than it had been when the same area was analyzed 20 years earlier. They concluded that the melting of the ice pack during the summer of 1997 caused the water to be proportionally less salty. Such a change can have serious consequences for marine life as well as for how ocean water circulates and interacts with the atmosphere. In addition to altering salinity, melting sea ice also raises worldwide sea levels, with potentially significant effects for coastal cities and towns.”
Of course, as any diligent fifth grader knows, Archimedes Principle states that an object immersed in a fluid is buoyed up by a force equal to the weight of the fluid it displaces. This implies that floating ice displaces a volume of water equal to the melted volume of the ice itself. Citizen Dave Burton noticed the discrepancy(2) and sent the NSF a message:
“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.”
And belying the usual claims of an unresponsive government controlled by a global conspiracy to distort science in order to bolster some hidden political agenda, the NSF did exactly as Mr. Burton asked, removing the last sentence, and adding the following note in its place:
“[Editor’s note: An inaccurate statement about sea ice and rising sea levels has been deleted. We regret the error.]”
A victory for common sense and democracy in action!
Only one problem. Mr. Burton was flat WRONG, and the NSF should not have listened to him. Sea ice is mostly fresh water because the salt quickly leaches out of it once it forms. Persistent sea ice, ice that has been frozen for thousands of years—the bulk of the global ice pack and the very ice the scientists are worried about–is entirely fresh. Salt water is denser than fresh water, so the volume of sea water needed to buoy a block of freshwater ice is slightly less than the volume of fresh water in the ice.
A layman like Mr Burton cannot be expected to know this, or to know that calculations show that, in fact, melting pack ice will increase the volume of the ocean by enough to raise sea levels by 4 centimeters(3) all by itself. But the scientists who did the field work know it, and the website administrator at the NSF should have consulted them before taking the word of a lay “armchair quarterback” over theirs.In fairness, the original NSF wording does overstate the risk from pack ice. But, if pack ice melts, it means the hundreds of thousands of years of accumulated snow sitting on the antarctic landmass and in Siberia are melting as well and THAT could raise sea levels by enough to flood the ground I am standing on, here in a suburb of Houston.
Those who think they have the simple solution usually don’t understand the problem. Those who think their devotion to radio talk shows and a subscription to Popular Science make them wiser than the best minds of an entire field of credentialed science are invariably wrong.
1 – http://www.nsf.gov/about/history/nsf0050/arctic/seaice.htm
2 – http://wattsupwiththat.com/2011/10/10/nsf-just-now-figures-out-archimedes-buoyancy-principle/#more-48978
3 – Peter D. Noerdlinger, Kay R. Brower “The Melting of Floating Ice will Raise the Ocean Level”, Geophysical Journal International, 2005
Seawater has a density of about 1025 Kg/m^3 and freshwater has a density of about 1000 kg/m^3, so if sea ice were entirely freshwater, then the melted fresh water would have a volume 2.5% greater than the seawater it displaced. Of course, unlike what you actually wrote this is not a 2.5% (or 2.6% to use your number) expansion of the ocean since the volume of sea ice is very small compared to the volume of the entire oceans. What is more, sea ice is not actually completely fresh water. The salt content of the ice below the waterline is commonly much higher and most of the sea ice is below the waterline. Even that above the waterline has some salt content and it is greater when the ice is newly formed.
Compared to the alarm many are spreading, a 4 cm sea level rise is very small. Sea level has risen much, much more since the end of the Little Ice Age for natural reasons. While sea ice volume in the arctic has sometimes been much reduced in the last 10 years, the ice coverage of Antarctica has generally increased in that time. Loss of volume at one pole does not imply loss at the other. As you know, the tilt of the Earth relative to the Sun varies and the effect on ice formation at each pole can be strong.
You’re quite right, and the implication of a 2.6% increase in ocean volume was an editing error on my part. The 4cm sea level rise, however, is correct.
Your comment on sea ice extent, however, is misleading. Arctic ice extent has been decreasing by a larger amount than increases in the south, and the Arctic ice is almost all multi-year ice, wherease in the antarctic, is is mostly seasonal. Arctic permafrost also sequesters tremendous amounts of methane, which is of course a much more potent greenhouse gas than CO2, so it’s release can create a feedback loop. It is a complex field, no doubt about it, and the answers are only going to come from rigorous science. Clearly the planet is warming and has been warming for a long time. We are probably making it warm just a list faster, and it’s not going to stop. Do we might as well stop arguing about it and start planning for the consequences.
But you know, we ought to be MORE worried about ice than heat. If you look at the recent history of ice ages, we are pretty close to where you expect the cycle to loop, temperatures to spike, then drop to where they were 20,000 years ago. Now, lost coastlines and food disruption would be bad, but we will survive. I doubt we could survive (at least as a civilization) if the glaciers once again invade north American latitudes. I don’t know how likely it is, but it is at least POSSIBLE that by burning all these fossil fuels, we might end the cycle, and skip the next ice age. That’s the premise of “Doomsday”.
I agree that an Ice Age or even another Little Ice Age would cause more harm to mankind than would a surface temperature increase of 2̊C. A number of solar astrophysicists are very concerned that the sun may have entered a bad cooling cycle. Such a cycle might cause a large decrease in crop yields and with 7 billion people to feed, this would be a very real disaster. Additional CO2 might be helpful in somewhat increasing production in shorter growing seasons.
The big difference between the Arctic and Antarctica is that most of the ice volume of Antarctica is land ice and it is not already floating in the sea. If it were to melt, which it fortunately is not, it would contribute many times more per kg of melted ice to sea level rise.
Even those who claim that CO2 will cause catastrophic warming claim that most of the effect is due to the small warming caused by CO2 causing a larger positive feedback of warming by increased water vapor. I believe this is wrong, because water vapor does more to cool the Earth’s surface than to warm it. It does this in many ways, but of particular importance is the fact that water vapor prevents incident solar radiation (UV, visible, and shorter wavelength infra-red) from ever reaching the ground. What is more, while CO2 and methane gas have less effect on absorbing incoming solar radiation, they form dimers and trimers with water vapor atoms that increase the wavelength range of the water absorption effect. This means increases in their concentrations will have an offsetting effect of increasing water absorption of incoming solar radiation. Little thought has been given to these effects to date in the climate sciences. The result is that such warming effect as CO2 and methane gas may have is offset by probable negative feedbacks by water vapor, which goes far to explain why the Earth has a great tendency to have a fairly stable temperature. The evidence is that it is not inclined to unstable runaway conditions and such changes as the Earth has experienced are dominated by changes in solar radiation.