Did Global Warming Stop After 2000?
2011 January 1
Second verse, same as the first.
So why bother? Completeness.
I used the data set prepared by O’Day over at Climate Charts & Graphs. Thus, we have charts for GISTEMP, HadCRU, NOAA, UAH, and RSS. The data for Dec 2010 is still missing – but I’m using the ave for Jan-Nov for the 2010 annual data.
The script is here
Satellite data does not extend far enough back to run 30 year trends. These are 20 year trends.
The Whiteboard 
Nice work, Ron.
Q1. The wider widths for the confidence intervals for UAH and RSS are due to the shorter datasets, correct?
Q2. Any chance you can make larger versions of the charts?
These eyes are getting close to 50 years of use & don’t work as well as they used to…
BTW, lost Open Mind posts through June 2009 now available here.
The Yooper
Hehya, Yooper.
Since you asked, you get to be the very first alpha-tester. Been working this weekend on porting some stuff to a new webhost. They told me they can’t support R. They didn’t tell me that I couldn’t compile my own static version and upload it. 😀
The naming convention should be self explanatory.
http://rhinohide.org/gw/trendtester/img/
If you want any other tweaks, let me know. But, to tell the truth, the script is so dead simple, you should be able to download R and run the script yourself!
As to Q1, sample size does play a role, as the inverse of the number of points is a factor in setting the 95% CI. On the other hand, a linear fit may not be the best fit (as in the case where the ‘natural’ or ‘real’ underlying trend is nonlinear), and the CI will increase as more points are added. See the next post where the GISTEMP CI decreases for 10,20, and 30 year intervals, but then starts increasing again at 50 and 60 years.
SIMPLE PREDICTIONS OF GLOBAL MEAN TEMPERATURE
From the historical global mean temperature data shown below
http://bit.ly/bUZsBe
the following patterns can be established:
a) 30-years of global cooling by 0.2 deg C.
b) Followed by 30-years of global warming by 0.5 deg C.
VERIFICATION
Let us start from the global mean temperature anomaly (GMTA) for the 1880s of -0.3 deg C, which was at the beginning of a cooling phase. As a result, we have:
1) For 1880s, GMTA = -0.3 deg C
2) For 1910s, a GMTA of -0.3 – 0.2 = -0.5 deg C
3) For 1940s, a GMTA of -0.5 + 0.5 = 0 deg C
4) For 1970s, a GMTA of 0 – 0.2 = -0.2 deg C
5) For 2000s, a GMTA of -0.2 + 0.5 = + 0.3 deg C
These results approximately agree with the data given in the link above!
PREDICTION
6) For 2030s, an approximate GMTA of 0.3 – 0.2 = + 0.1 deg C
CONCLUSION
Global cooling until 2030!
Did Global Warming Stop After 1998?
Let us look at the data shown below:
http://bit.ly/dQ8S9i
This data shows the decadal trend flat at 0.4 deg C.
CONCLUSION
Yes, global warming stopped after 1998!
Girma, Wood-for-Trees uses an inclusive start and an exclusive end. You are chopping off 2010 instead of including it. Either set the end date to 2011, or just leave off the end date as such:
1998
http://www.woodfortrees.org/plot/hadcrut3vgl/from:1998/to:2011/plot/hadcrut3vgl/from:1998/to:2011/trend
http://www.woodfortrees.org/plot/hadcrut3vgl/from:1998/plot/hadcrut3vgl/from:1998/trend
2000
http://www.woodfortrees.org/plot/hadcrut3vgl/from:2000/to:2011/plot/hadcrut3vgl/from:2000/to:2011/trend
http://www.woodfortrees.org/plot/hadcrut3vgl/from:2000/plot/hadcrut3vgl/from:2000/trend
Also, you can add the most recent decade to your chunky trends located in the first link so: http://www.woodfortrees.org/plot/hadcrut3vgl/from:1880/to:1910/trend/plot/hadcrut3vgl/from:1910/to:1940/trend/plot/hadcrut3vgl/from:1940/to:1970/trend/plot/hadcrut3vgl/from:1970/to:2011/trend
You will notice that your chunked up trends resemble the linear or exponential trends plus a sine fitted to the residuals that can be found here:
https://rhinohide.wordpress.com/2011/01/14/lines-sines-and-curve-fitting-6-backcast-and-forecast/
Ron
How about this one?
http://bit.ly/cO94in
Interesting, Girma.
How did the author select the sine parameters (amplitude, period, phase shift)?
Ron
Here are the details:
http://bit.ly/gaA9kS
Regards
It appears that you kind of fit it by hand. Did you ever check to see if 55 years or 65 years made a better fit for the period? If 0.25C or 0.35C for amplitude fit better than 0.3C?
The main issue is the model has a high correlation coefficient of 0.88 as shown below:
http://bit.ly/f7VYQH
As a result, the global mean temperature pattern is cyclic with a slight overall warming of 0.6 deg C per century.
!!!Global Cooling until 2030!!!
Dr Orssengo, I asked you a couple of simple questions which you have not answered.
I’ll ask them again.
1. Did you fit the curve by hand?
2. How did you check to see if there were better fits?
And now a third question, given your comment about ‘the main issue.’
3. If I can find a simple equation like “line + sine” that provides a better correlation, would that be a better model than your “line + sine” model?
Ron
From the following global mean temperature data of the CRU
http://bit.ly/fizsCE,
I selected the following values in deg C to fit the curve:
Year => Anomaly => Model
1880s=> -0.2 => -0.22
1910s=> -0.6 => -0.64
1940s=> 0.1 => 0.13
1970s=> -0.3 => -0.29
2000s=> 0.5 => 0.48
Is it not the agreement between data and model very good?
http://bit.ly/cO94in
Yes, Dr Orssengo, the agreement between the data and the model is very good.
See. I just answered one of your questions. It started with ‘yes.’ It is an easily understood answer. I still don’t know if you selected the values in your equation by hand. I still don’t know if you looked for better fits. And I still don’t know whether you think the model with the best correlation is the best model.
If I provide a better agreement between data and model with a model just as simple as yours, would my model be better?
Ron
“If I provide a better agreement between data and model with a model just as simple as yours, would my model be better?”
YES
However, my model has a very high correlation coefficient of 0.88. As a result, any higher correlation is not necessary.
The main test is, as predicted by the model, will we have global cooling until 2030?
That is the main test. If we have this cooling then we can say the model is a good model.
Kind regards
Are these statistics significant, with respect to IPCC AR4 projections of 0.2C/decade from 2001. I think they use Hadcrut, which is a negative trend from 2001 to Dec 2010.
ant1: are slower than 0.2C more like 0.17C for the last 30 years (taken together)?
When you ask if there is a significant difference in trends between this and the IPCC projections, I suggest that Lucia’s construction provides a better answer. All the global temp indices easily fall within the 95% confidence interval of the IPCC’s projection, although they are on the low side.
http://rankexploits.com/musings/2011/hadcrut-december-anomlay-0-251c/
ant1
Here is comparison of IPCC projections with data:
http://bit.ly/cIeBz0
Note that the new value for 2010 of 0.475 deg C is still BELOW projections had CO2 emission been held constant at the 2000 level.
As there is no warming of 0.2 deg C per decade, IPCC projections are wrong.
Thanks Ron and Girma. You have really cleared this up with 2 different graphs and values for A1B scenario. Do they use different baselines? Is such a graph in AR4 as I can’t find it?
I think Lucia’s other graph is a more pure test of the independant 0.2C/decade projection.
I was under the impression that the 95% confidence interval would be zero trend. Is that correct?
Ant, the 95%CI is built around a model projection. If the model shows an increase, the CI will increase with it. In a linear model with time invariant variance (heh!), the CI will form a steady +/- envelope around the linear trend. But I don’t think that is the case with an exponential model. I’ll know soon enough. That is a topic that I am working on now.
To answer one of your questions, Girma, ‘when can we know which model reigns supreme: line+sine or exp+sine?’, we need to be able to place confidence intervals around the two projections. If future temps fall within the CI of one trend but not the other, we can rule out the other. That’s what I am working towards right now.
And Girma … I wouldn’t presume too much in how RealClimate feels about me or this blog. You might be surprised. 😆
Ron
RealClimate don’t let me post a word!
They do.
Try it and you will find out.
Girma,
For what it’s worth: most of your comments look like “drive-bys”. You say what you have to say and you go away, only to return in a later discussion, with more of the same post. You must understand that moderators tend to get a bit ticked off by these kinds of posts, more so when they’re critical without being negotiable.
You might be serious and well-intentioned, but your posts are not contributing to the discussion, most of the times. I, for one, stop reading drive-bys. I am very skeptical that they work and they invalidate your claim that “yes, but RC moderation.”
I am saying this because you answered my question in the other thread. That was enough for me to show your willingness to discuss.