Sunshine hours writes:
I have been a bit worried about the deep deep dive in Antarctica Sea Ice Extent.
It appears to be a processing or sensor error. As of today the NSIDC data confirms it. (see image below)
In a deja vu all over again moment, I find that it isn’t just the Antarctic with wonky readings.
I agree that looks like a sensor failure of some sorts, and this NSIDC graph looks a bit odd as well. NSIDC uses a 5 day average, so the transients get smoothed out.
This Arctic graph from DMI has what appears to be a spurious element also, note the recent uptick:
(added: that uptick could be wind affecting the ice extent, or it could be a sensor/processing issue, we simply don’t know)
Tomorrow there will be a new paper released by former NSIDC scientist Walt Meier and others that tries to argue that some of the record sea ice extents from Antarctica recently are a victim of an adjustment in a processing algorithm that changed in 2007 from Version 1 to Version 2.
Back in 2009, in the “deja vu moment” I wrote:
In the prior thread I raised a question of why there was a large downward jump in sea ice extent on the graph presented by NSIDC’s Artic Sea Ice News page. The image below was the reason, dozens of people called my attention to it in emails and comments overnight because in the space of a weekend, a million-plus square kilometers of Arctic sea ice went missing.
Walt Meier wrote this response that he later had to eat crow for:
Thus errors do happen from time to time and one shouldn’t draw any dramatic conclusions from recent data.
I’m not sure why you think things like this are worth blogging about. Data is not perfect, especially near real-time data. That’s not news.
Now, Meier has an entire paper about such errors, and the error is far lower in magnitude than that incident where the sensor actually did fail and NSIDC was caught napping.
It makes me wonder just how good these estimates of sea ice are; what else awaits discovery?
I wish they’d exhibit the same investigative zeal when it comes to looking at Arctic sea ice record low extents, for all we know, the 2007 low extent might also be a victim of the same algorithm shift that occurred that year.
But you see, confirmation bias prevents such investigations, they expect the Arctic to be low, so they only looked at the Antarctic where there’s more ice than there is supposed to be. To paraphrase their viewpoint on it: “it didn’t look right”.
On the plus side, it looks like this means the AR4 and AR5 reports are wrong about sea ice extent values, and as we know IPCC reports are wrong about a lot of things.
We’ll have that new paper here at 6AM ET tomorrow.