I took some flack on how I missed such an obvious problem in the data. Well, things are rarely as clear as they first seem. Let’s look at the facts, below is a plot of the uncorrected bootstrap data.
See the offset at 1987, no how about the same graph zoomed in.
There it is, that little scribble after 1987.5. That’s the entire difference between my first and second posts. But it’s worse than just this, here is some text from the actual pages.
Well tonight I get the great pleasure of redoing a post in the face of an inconvenient truth. To add insult to injury the error in my ways was pointed out by none other than my favorite liberal – Tamino who pointed out this section of the NSIDC data center. How I missed it in the hours I spent reading the site is beyond me. He did owe me one, at least we know he’s reading.
Note that unlike ice extent, the Arctic values for ice area do not include the area near the pole not imaged by the sensor (the “pole hole”). This area is 1.19 million square kilometers for SMMR (from the beginning of the series through June 1987) and 0.31 million square kilometers for SSM/I (from July 1987 to present). Therefore, there is a discontinuity in the “area” data values in this file at the June/July 1987 boundary.
This means that the sea ice area prior to 1987 was actually 0.88 million kilometers higher than the dataset indicated (if we assume 100% filled). Why it isn’t corrected in the data is due to the fact that the actual fill level is less than 100%. This results in an exaggerated downslope. Anyway here’s the new graphs (with a somewhat exaggerated downslope).
Here’s an image from the IUIC cryosphere page first which shows global trend.
Here’s the link check it out yourself. This isn’t that different from my original post but there is some down slope.
———————–Results from my exaggerated correction are below. ——————————–
Raw data looks like this after adding 880000 km^2 to the raw data before 1987.
This post contains an error in data interpretation. The NSIDC provides the data in a continuous time series, in their well documented site they describe an upgrade in satellite at 1987 which resulted in an upward offset in the data prior to 1987. Despite hours reading the website I somehow missed this offset which makes my analysis incorrect. Sea ice totals have decreased as advertised although the trend is less than we hear. Sorry for the confusion.
Jeff Id
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I calculated a true global sea ice anomaly in this post using the National Snow Ice Data Center data. What would you say if I told you that over the last 30 years the sea ice area has stayed flat or even trended — Up!!!???
This isn’t a small deal. We have been told, well screamed at really, that CO2 is causing unprecedented rise of temperature on a global scale. We hear constantly that the ice is melting and the result will be dramatic flooding of the earth; movies have even been made. Those of us who pay attention to the scientists have heard that the most significant warming will be at the poles (according to the computer models). We also hear that the Antarctic has added ice during the same time the Arctic lost sea ice. This is explained in that the Antarctic ice increase is a local situation and the Arctic ice loss is a result of global warming. A unique form of cherry picking but should be treated with an open mind.
This post contains data which was mislabeled as Sea ice exent. When all data used was accidentally sea ice area. The post is otherwise valid. For an updated version of it
I have been working on sea ice data for the last week. Learning the collection methods and the differences between the data. I have found several interesting things, some of which will be discussed in future posts. There are two main methods being used for calculating sea ice extent at NSIDC. Data page is HERE.
Nasateam is the original method which was discovered to have a few problems in accuracy, however the overall trend is quite similar to the newer bootstrap method. Both have some problems but the trend is quite accurate. We only hear about the northern hemisphere, although the data for the southern hemisphere has equal quality.
Let’s look at the northern hemisphere nasateam algorithm data first.
The red line is the overall trend for up to 2006 which is the length of the data on the site. The slope is -0.02618 million km/year or 2.6 million Km^2/century. I didn’t want to use the ice anomaly data as presented by our govt scientists so I used my own method. To keep it simple, I separated the data into years and averaged all the same dates together. All the Jan 1’s 2’s 3’s …… I got the following curve.
I have been working on a post on sea ice. As many of you know I am fairly new to climatology and am learning as I go. This means every post requires more work and study than it appears. Well tonight in my hours of study I ran across something interesting. Well rather surprising. Many of us have seen the northern hemisphere sea ice but how many of us have seen the global ice extent charts.
Anecdotally I have heard that antarctica, long ignored as the butt of the world has been growing ice. I also have read and seen graphs indicating that it isn’t enough to compensate for the arctic loss. I never have added the totals together from north and south so I beleived what I heard. Of course, the reports consistently sound like bad news for the earth overall. Well I found a graph today, and not a small one physically or meaningfully.
Sorry about the size, I can’t make thumbnailing work but look at this beast. The link to the full size image is below.
This is the global sea ice measured by satellite. Where’s the warming is what I want to know? All we hear about is the northern hemisphere but the global numbers haven’t changed much at all.
Here’s the link check it out yourself.
This is really stunning to me, not what I expected at all. The data above is collected by satellite reflection of ocean surfaces, it is harder to mess with. I would tell anyone to read the info yourselves and don’t trust the news but it is good to remember that even I am not immune.
There isn’t any real ice melting going on in the 90’s whatsoever and after 2000 it is incredibly minimal.
I had been working on what I used to consider more interesting stuff but now my head is spinning on this one.
Can anyone help me verify this by a different organization? Not that the University of Illinois is a bad reference. Wow!!
I have to be missing something.
the Air Vent 