Key Insight
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 ... Read more
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.
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.