Arctic Springtime Ice On The Mend
Guest post by Steven Goddard
Two of the Arctic ice sites show April 16 ice at recent record levels. The Japanese site IJIS has a seven year April record going back to 2003, and reports 2009 levels at the highest extent on record for the date: 13,649,219 km2.
The Danish Meteorological Institute has a five year database, and also shows April 16 ice extent as the highest in their short record.
A plot of April 16 extent made from the IJIS database shows that mid April ice extent has made a nice recovery from the 2004 low, increasing by more than 5%.
This is probably not coincidental with the fact that since 2003, global temperatures have been declining.
Next time Washington Post writers decide to bash George Will about ice, perhaps they should check their facts first. The comment below from that piece shows just how irrational the thinking of climate “journalism” has become.
“citing “global” sea ice statistics like that is nearly meaningless in the context of global climate change”
Why would you use “global” statistics when examining a “global” problem? What was George thinking of?
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Steve Goddard
I am a big fan of WUWT and enjoy your postings. This is a great article about sea ice and I am glad there are people like you presenting the other side to these arguments. Please do not take the following argument as an attack on you or your work. However, I do disagree with your assertion that based on this RSS data shown in your article, temperatures have been trending lower since 2003. I pulled up the RSS data on wood for trees all the way back to the late 1970s. The graph shows that temperatures have basicly moved sideways from the late 1970s through the early 1990s. Starting from the low in the early 1990s, there is a clear uptrend formed by connecting the lows of the data series. If you draw a parellel line connecting the highs together you get a nice uptrending channel, except for the spike high put in during 1998. We know this is an aberation because of El Nino and because the measurements came back into the uptrending channel and remained there until 2007. In mid 2007, the trend line was broken on the downside and it is currently still below this trend line.
In my opinion, your contention that temperatures have been in a downtrend since 2003 is not supported by this data. You can not use a simple linear trend line to determine when the trend change occurred because it is highly dependent upon what year you start and end the linear trend and the magnitude of the current drop (the steeper the drop the farther back you can go and show a downward linear trend line).
For example, your graph shows the linear trend falling from 2003 to 2009. But you could even go back to 2001 and still show a downward linear trend to 2009. If you do a linear trend from 2003 to 2006 it is flat and from 2006 to 2009 a steep downward trend. If you do a 10 year linear trend 1999-2009 it is an upward trend. The point is you can play around with linear trends all you want, but they are not a good indicator of when the change in trend occurred.
When temperatures or other mesurements are trending higher you expect to see higher highs and higher lows as the trend progresses, with a degree of variability within this rising trend channel. This is exactly what this data shows with the trend line being violated in mid 2007, representing a change in trend. In this case it appears the temperatures are trending sideways or lower after mid 2007, but not prior to this. Other data sets may show a different result. I am only commenting on this RSS data set. Thank you for pointing out the woods for trees site. It is interesting to play around with the numbers and see the effects. mike borcherding
Mike B (18:48:06) :
The question really is “is the downward trend noise (weather) or will the trend continue?” Try looking at a plot of smoothed Hadcrut (try 120 months for example) and you’ll see a peak around 1940 and one about 1880 (about 60 yrs or so). We’re about 60 yrs after the last peak so I’m getting confident that we’re in a downturn for maybe the next 30 yrs. There is also a underlying positive trend so the trough may be higher than the last minima but I think it’s going to look like the trend has gone negative for awhile. You can detrend using about a 0.8 value to see the peaks easier.
if this works heres a plot
http://www.woodfortrees.org/plot/hadcrut3gl/mean:120/detrend:0.8
today21/04/2009, Dr Harrison of UK Appleton Rutherford lab stated that in the case of low solar activity there willbe minimal effect on AGW