Another low: Richard Verney's Arctic sea ice fudge at WUWT

Some of the "thoughts" of deniers at WUWT defy belief. I'm talking about a comment from WUWT regular Richard Verney today under an unusual article (for WUWT). The WUWT article was unusual because despite being posted by Anthony Watts, and despite it being a press release from a scientific organisation, and despite it being about how winter sea ice hit another record low maximum this year - there was no "claim" in the headline (archived here, latest here).  There was even a link to the NASA press release.

This is the comment that I'm talking about, from richard verney on March 29, 2016 at 1:48 am

They have satellite data going back to the early 1970s. They should use all the data, not just that post 1979, but then again the early 1970s would be inconvenient especially since the amount of ice observed today is more than in 1974.

He's wrong in his conspiracy ideation. The amount of Arctic sea ice observed today is a lot less than it was in 1974. Here are some plots of sea ice extent going back as far as the satellite era will travel.

The first is the average annual:

Figure 1 | Annual average Arctic sea ice extent. Data source: NOAA

The next is the September mean, the month when there is least ice:

Figure 2 | September average Arctic sea ice extent. Data source: NOAA

 The next is the winter maximum month (March). This year's data only go to 27 March at the time of writing this article, so it's not the full month:

Figure 3 | March average Arctic sea ice extent. Data source: NOAA

Richard Verney's "proof" was a chart he got from "Steve Goddard", who got it from the IPCC first assessment report FAR. Notice the scale on the left hand side:

Figure 4 | Northern hemisphere sea ice extent as reported in the first IPCC Assessment Report FAR (1990). Source: IPCC via WUWT via "Steve Goddard"

The text of the IPCC report says this is from US Navy Joint Ice Center data:

Sea-ice conditions are now reported regularly in marine synoptic observations, as well as by special reconnaissance flights, and coastal radar. Especially importantly, satellite observations have been used to map sea-ice extent routinely since the early 1970s. The American Navy Joint Ice Center has produced weekly charts which have been digitised by NOAA. These data are summarized in Figure 7 .20 which is based on analyses carried out on a 1° latitude x 2.5° longitude grid. Sea-ice is defined to be present when its concentration exceeds 10% (Ropelewski, 1983). Since about 1976 the areal extent of sea-ice in the Northern Hemisphere has varied about a constant climatological level but in 1972-1975 sea-ice extent was significantly less.

Arctic sea ice from 1953 to 2011

In 2012, Walter Meier and co had a paper published, in which they put together a longer series going back to the 1950s. They wrote how the data sources weren't consistent before 1978:

Observations from passive microwave satellite sensors have provided a continuous and consistent record of sea ice extent since late 1978. Earlier records, compiled from ice charts and other sources exist, but are not consistent with the satellite record. Here, a method is presented to adjust a compilation of pre-satellite sources to remove discontinuities between the two periods and create a more consistent combined 59-yr time series spanning 1953–2011.

The authors explain that although there is some pre-1978 satellite data, it can't be simply spliced to the more recent data:

Various pre-1979 data products exist, including some passive microwave data from an early single-channel radiometer, but these are primarily based on operational ice charts produced in support of navigation in the Arctic.

Here is a chart from the 2012 compilation. I've put a rectangle around the years that Richard posted and added some lines for the highest and lowest monthly mean extents in that period:

Figure 5 | The monthly standardized anomaly for January 1953 through December 2011, relative to 1981–2010 average period. Each value is the monthly anomaly normalized by the standard deviation for the month. Monthly values are in dark blue; a 12-month running mean is overlaid in pink. Source: Meier12

It's different to what was estimated back in the late 1980s. The range in Richard Verney's FAR chart is only +/- one million sq km. In the Meier 2012 chart, the range is expressed as standard deviation, but going by Figure 1 above, it's probably around +3 m sq km to -1 m sq km, with most years having a minimum at the zero line.

Regardless, it should be obvious that Richard is wrong. The current sea ice extent in the Arctic is way below what it was in the 1970s.

From the WUWT comments

I figured it might be interesting to see if anyone quibbled with Richard. The times they are indeed a changin'. Two people did.

markstoval complained he couldn't win with these "bloody blokes":

March 29, 2016 at 3:11 amI showed this graph to a science teacher a few years ago and was told it was a bogus fantasy. I then revealed the source as the IPCC (originally NOAA) and was told that the data and graph were old and therefore worthless. Newer algorithms and so on now reveal that the ice is all melting and the polar bears are going to go extinct.
Jesus, Joseph, and Mary you can not win with these bloody blokes. You show them data from the freaking IPCC and they discount it. What good would independent data from some science group do?
There is nothing happening now that has not happened before, and we live in an amazingly stable epoch in time climate-wise.

Phil. just quietly pointed out that Richard is wrong:

March 29, 2016 at 3:15 am
Hardly Richard, the current max is about 2million sq km below the 1979 value.

Patrick in Adelaide needs a lesson or two or more in how to read a chart. Hint 1: read the caption to see what the baseline period is. In this case it's absent for the IPCC chart, but the baseline for Figure 4 is obviously an earlier period than that of Figure 5. Hint 2: read the numbers on the Y axis:

March 29, 2016 at 4:02 am
Phil, is it below the 1974 max value that Richard mentioned? Looks like 1979 experienced a larger extent.

 I might as well tell you of some of the other comments while you're here. Paul Homewood seems to think that seas heat up by magic, writing:

March 29, 2016 at 3:41 am
. But ultimately, what will likely play a bigger role in the future trend of Arctic maximum extents is warming ocean waters,
Precisely. And the warmer waters are the result of ocean currents and not CO2, which can not have any significant effect on ocean temperatures

AndyE bemoans the fact that the Vikings didn't launch any satellites:

March 29, 2016 at 2:48 am
Why, oh why didn’t the Vikings send up satellites to check on what it was like sailing there then??

Rasa is a plain conspiracy theorist, who assumes "something must be wrong" and "nefarious intent" - and the deniers' favourite "money":

March 29, 2016 at 1:55 am
The guys from NASA and their mates are clowns. For a system that changes over Millenia these guys are trying to create a statement for the three months of a year.
Overwhelmingly the alarmists, including sections within NASA, BOM, Universities have corrupted the science process. They all start with the desired outcome then try to creat a trail leading to it. Invariably their science is ridiculed and reinforces the views of skeptics.
I suppose you cannot blame them for trying to preserve their taxpayer funded careers. 

marcus has learnt something new today. Will it stick?

March 29, 2016 at 1:31 am
“In places where sea ice has been lost, those areas of open water will put more heat into the atmosphere because the air is much colder than unfrozen sea water,” Francis said.

….So it is a warmer ocean, not a warmer atmosphere that is melting the sea ice ?

References and further reading

Meier, W. N., Stroeve, J., Barrett, A., and Fetterer, F.: "A simple approach to providing a more consistent Arctic sea ice extent time series from the 1950s to present," The Cryosphere, 6, 1359-1368, doi:10.5194/tc-6-1359-2012, 2012. doi:10.5194/tc-6-1359-2012 (open access)

2016 Arctic Sea Ice Wintertime Extent Hits Another Record Low - NASA press release, 29 March 2016

Houghton JT, Jenkins G, Ephraums JJ. "Climate Change: The IPCC Scientific Assessment." (1990). (pdf here)