Weekend update: Debate heats up on impact of melting north pole on sea level rise!

Holy smokes!

NOAA has been prevailed upon to reverse its previous position on whether the melting of the  North Pole icecap will affect sea levels!

Until yesterday, the position of the agency, as least as reflected in its “Arctic Theme Page FAQ,” was, “No”:

Well, after I suggested that anyone of the 14 billion regular readers of this blog who disagreed w/ me that seal levels wouldn’t rise should “take it up with NOAA,” someone apparently did — & got the agency to change its view:


But what’s the explanation? You won’t figure that out from the new FAQ…

It isn’t disputed (except by 5 people who wrote me emails…) that a piece of floating ice (an ice cube, say, in a glass of water) displaces a volume of water equal to the volume of liquid water it turns into when melted.

Also it isn’t disputed that the North Pole ice cap is simply floating on the arctic sea (although I did hear from a couple of people who said it isn’t right to call the “ice cap” on the North Pole an “ice cap”; they should take it up with NOAA too!).

Apparently, though, there is reason to think that “little” is the right answer to the question.

The floating ice at the North Pole is frozen fresh water (not quite but close!), while the body of water in which it sits — the Arctic Sea — is salt water.  Salt water and fresh water have different volumes, and apparently this means that less water is displaced by a frozen piece of fresh water than is added to the salt water when that ice melts.

Or so says the source — a Nature Climate Change blog — that I’m told was brought to NOAA’s attention.

Summarizing an article from Geophysical Res. Letters, the blog states, “[r]etreating Arctic sea ice and thinning ice shelves around Antarctica contribute about 50 micrometers, or half a hairbreadth, to the 3 millimeter or so annual rise in global sea level…”

Presumably the amount contributed by the melting North Pole ice cap is smaller, since the GRL paper states that over 99% of the world’s floating ice is in the Antarctic.

But even 1% of 1/2 a hairsbreadth still is something!

Another blogger who noticed this article stated:

Melting sea ice or ice shelves can indeed change sea level. It turns out that I was probably the first person to compute by how much the sea ice can do so, and there’s a story for tomorrow about why I wasn’t the person to publish this in the scientific literature even though I had the answer more than a decade before the next person to look at the problem.

I’m not sure if that day came– be interesting to hear the story.

But look: good enough for NOAA & the Geophysical Res. Letters, double good enough for me!

I have to say though that even if the old NOAA FAQ was poorly worded (as climate scientist Michael Mann stated yesterday on twitter when he kindly responded to my plea for help in sorting through all this) the new NOAA FAQ still strikes me as below the agency’s usually stratospheric standards.

The old answer at least made sense.  The new one doesn’t — b/c it doesn’t furnish any explanation for how melting floating ice will raise sea level a “little.”

Indeed, the “so” in the new NOAA FAQ–“Ice on the ocean is already floating, so if the North Pole ice cap melts it has little effect”– strikes me as a true non-sequitur.

How much the melting fresh-water ice raises sea level depends on how much volume it has relative to the body of salt water it sits in. So if the melting ice in the North Pole will raise sea levels but only a “little” — as seems to be true– the explanation is that the volume of floating ice is comparatively small, not that it is “floating,” a fact that by itself would imply its melting will have “no effect,” just as the the old NOAA answer stated.

If the goal is to help people comprehend, then it is necessary to give them a cogent explanation, not just a “true”/”false” answer for them to memorize.

But hey, I’m really glad that my “climate science literacy” test apparently helped to get this straightened out!  Indeed, I feel smarter now!

Still, I’m worried I might have opened up a can of frozen worms here…

There are lots & lots of additional credible science authorities on-line that draw the distinction the old NOAA FAQ did between the melting sea-ice floating in the Arctic or North Pole region (“no effect– like a floating ice cube!”) and melting ice sitting on land masses at the Antarctic or South Pole region & elsewhere.


Moreover, the internet is teaming with helpful sources that show middle-school and high-school science teachers how to create an instructive science exercise based on the difference between the floating North Pole ice cap and the land-situated South Pole one:

Indeed, I suspect skilled teaching could explain an interesting feature of the results I obtained when I administered my proto- science-literacy instrument to a national sample.

A full 86% of respondents classified as “true” the statement “Scientists believe that if  the north pole icecap melted as a result of human-caused global warming, global sea levels would rise.”

But the 14% that answered “false” clearly had a much better grasp of the nature and consequences of climate change.

E.g., two other true-false items stated:

Climate scientists believe that human-caused global warming will increase the risk of skin cancer in human beings;


Climate scientists believe that the increase of atmospheric carbon dioxide associated with the burning of fossil fuels will reduce photosynthesis by plants.

On each question, over 2/3 of the respondents got the wrong answer.

That’s not good.

It suggests that most of the 75% of the respondents who correctly selected “CO2” as the gas scientists believe increases global temperatures still don’t really know very much about climate change.

If they did, they wouldn’t think that “skin cancer” will increase. That’s suggestive of the long-standing confusion that a hole in the ozone is causing climate change.

Also, if they really got that CO2 is causing climate change b/c it is a “greenhouse” gas, they wouldn’t believe that climate change is going to starve the plants that live in greenhouses….

But here is the critical point: if a study participant answered “true” to “North Pole” — that is, if that person indicated he or she thinks climate scientists believe that a melting North Pole ice cap will raise sea levels–then there was a 67% chance he or she would get both the “skin cancer” and “photosynthesis” items wrong!

In contrast, there was less than a 25% chance that someone who answered “false” to North Pole would answer those questions incorrectly.

It might be the “wrong” answer, but actually, “false” in response to “North Pole” is a better predictor of whether someone is likely to show comprehension of other fundamental facts about climate change.

And in fact, that is what a test item on an instrument like this is supposed to do.

The function of a good science-comprehension instrument isn’t just to certify that someone has absorbed or memorized the “right” responses to a discrete set of questoins.

It is to measure a latent (i.e., not directly observable) quality of the test-taker — her possession of the dispositions and skills that contribute to acquiring additional knowledge and giving it proper effect.

The proto- climate-literacy instrument in fact measures that capacity more accurately when one scores “false” as the “correct” response!

Actually, maybe “false” is the right answer to “North Pole”? Perhaps, as the NOAA FAQ prior to yesterday, and all the myriad other science sources on-line reflect, most “climate scientists” do “believe” mistakenly that a melting North Pole won’t raise sea levels?

No idea!

For sure, though, I’d revise this item in refining and improving this proto- climate-literacy instrument.

But one last point: in relation to my purpose in constructing the instrument, none of this matters!

My goal was to test they hypothesis that survey items that ask respondents whether they “believe in” human-caused climate change don’t actually measure what they know’; instead they measure who they are as members of competing cultural groups for whom positions on this issue have become badges of membership & loyalty.

Using techniques that have proven effective in determining whether “belief in evolution” measures science comprehension (it doesn’t), I devised climate-literacy items designed to disentangle indications of knowledge from expressions of identity.

The results suggested that there is indeed no relationship between what people say they “believe” about human-caused climate change and what they know about climate science.

Because there is clearly no meaningful relationship between getting the “right” or “wrong” answers on the proto- climate-science literacy test and either people’s cultural identities or their beliefs about climate change, it doesn’t matter which answer one treats and which as wrong in that respect. That is, there is still no relationship.

To me, that’s really really good news.

It means that the ugly, mindless illiberal status competition associated with competing positions on “belief” in human-caused climate change doesn’t impel people to form polarized understandings of what science knows.

However confusing it might be to figure out what “scientists believe” about the impact of a melting North Pole on sea levels, people– of all cultural & political outlooks — have already gotten the memo that climate scientists believe human-caused climate change is creating a series of challenges that need to be addressed through collective action.

Now it is time for those who are trying to promote constructive public engagement with climate science to get the memo that disentangling climate science from culturally assaultive forms of political action is the single most important objective they all confront.

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