Finally!!!! This has been frustrating for me. I once found some ice date going back to 1973. This was a couple of years ago. I hadn’t been able to locate it since. I was looking for something different at the time, so I didn’t mark it.
Readers of Steve’s Real Science will know that periodically he writes posts regarding the Arctic Sea ice prior to the 1978-1979 starting point most people see, because that’s what our public servant scientists always shows us. Here’s a recent post of Steve’s in this regard. And, here’s a graphic that he often uses, which is from the 1995 IPCC report.
But, I’ve always wanted some hard numbers to back that up. Remembering that I once saw said data, but, couldn’t find it again, has bothered me for a long time. It’s been said, if you lose something, start doing what you were doing before and you might find it. Wouldn’t you know it, I was on a search for some different data and I stumbled across the same old data, once again!!! So, what of this data? See below the graphs for details and links.
The data does not correspond exactly with what NSIDC puts out today. (Yes, that’s a huge surprise) All climate data has been altered from the original. Still, it isn’t as if it isn’t any different than any other sea ice data set. They’re all different with different values, but, strongly correlate. Here’s what the overlap looks like, 1979-1990. Note that these are monthly values.
But, what does the data look like before 1979?
Well, okay. Many are not as experienced at looking at graphs and having the data jump out at you. So, this graph may not be as obvious to some as it is to others including myself. I can’t put a trend line on this, because, as frequent commenter, Scott, would note, this would introduce a bias because of the start and stop points. So, to the anomalies we go. In retrospect, I should have extended the period I used, but, it won’t make any difference to the general point I’m making. I averaged each month’s value for the 1973 through 1978 period and then subtracted that average from each month to get the anomaly. Here’s what it looks like on a graph.
Yep, in 6 short years, the Arctic sea ice gained 800,000 sq kilometers. To put that in perspective, here’s an anomaly graph of the Arctic sea ice to the present, sans the earlier data, of course.
Yep, the gain then was more than the loss now, but, not as much as some loss in the recent past.
Please note: I’m not saying if this data was added that we wouldn’t have still seen a general decline in the arctic sea ice over the last couple of decades, I’m certain we would. But, it would be less pronounced. That’s not the point. Actually, there are a couple of points to be made here.
First, clearly, the start point of the data put out for the public is an act of deception. They’re intentionally deceiving people. And, without explanation, they’re pretending the sea ice of 1979 is the supposed norm and not anomalously high. But, it is. That period was exceptionally high. We should not be comparing today’s sea ice extent to a period of exceptionally more extent and pretending that there’s something very wrong.
Secondly, it isn’t what we can see, even with this additional data, it is rather what we can’t see. There’s a published work out there, where some pinhead tried to invent ice extent values going back decades, and like a good propagandist, the pinhead pretended that the ice was stable prior to the recent decline. This data puts that publication into high question.
Lastly, a word of caution. Some would be tempted to just slap this data onto the data the NSIDC puts out or some other modern set commonly used. Don’t do that. I’m not saying it can’t be done, but, if one was to attempt it, it would require rigorous math and statistical application. Not like Rhamy or Mann, but, real math and stats.
Okay, not lastly. Another note. It seems the two different data sets did a better job or more closely matching in the southern hemisphere.
I would say the reason for this is that it’s probably easier in the SH than the NH. Still, that’s bothersome. Oh, and just for the curious, as the NH ice was increasing, the SH was in a sharp decline.
Apologies if this seemed a bit rambling. I’m tired.
Sea ice extent from January 1973 through August 1990 was digitized from weekly operational sea ice charts produced by the Navy/NOAA Joint Ice Center. Charts were digitized by hand using a 1 degree latitude x 2.5 degrees longitude grid. The grid boxes were then summed in 1 degree latitude x 10 degrees longitude slices, and the ice covered area computed. The data represent the extent of sea ice at the end of each month, given for 36 10-degree longitudinal sectors in each hemisphere. Data were provided by the NOAA National Weather Service National Meteorological Center (NMC) Climate Analyses Center (CAC).
The following example shows how to cite the use of this data set in a publication. For more information, see our Use and Copyright Web page.
Ropelewski, C. F. 1983, updated 1990. NOAA/NMC/CAC Arctic and Antarctic Monthly Sea Ice Extent, 1973-1990. [indicate subset used]. Boulder, Colorado USA: National Snow and Ice Data Center. http://dx.doi.org/10.7265/N5Z60KZ1.