Is Spencer Hiding the Increase? We Report, You Decide
by Roy W. Spencer, Ph. D.
One of the great things about the internet is people can post anything they want, no matter how stupid, and lots of people who are incapable of critical thought will simply accept it.
I’m getting emails from people who have read blog postings accusing me of “hiding the increase” in global temperatures when I posted our most recent (Dec. 2009) global temperature update. In addition to the usual monthly temperature anomalies on the graph, for many months I have also been plotting a smoothed version, with a running 13 month average. The purpose of such smoothing is to better reveal longer-term variations, which is how “global warming” is manifested.
But on the latest update, I switched from 13 months to a running 25 month average instead. It is this last change which has led to accusations that I am hiding the increase in global temperatures. Well, here’s a plot with both running averages in addition to the monthly data. I’ll let you decide whether I have been hiding anything:
Note how the new 25-month smoother minimizes the warm 1998 temperature spike, which is the main reason why I switched to the longer averaging time. If anything, this ‘hides the decline’ since 1998…something I feared I would be accused of for sure after I posted the December update.
But just the opposite has happened, with accusations I have hidden the increase. Go figure.
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“DirkH (14:16:04) :
[…]
Why did the mighty GCM’s fail to forecast this? (hindcasting doesn’t count!)”
To clarify: fail to forecast the lack of significant warming in the last decade.
I don’t get it; 13-month or 25-month smoothing average, temperatures haven’t risen since 1998 as I look at the graph.
Mariss
Does a text file of the monthly average data exist? I’ve not spotted a link here, so any advice would be appreciated. Don’t really want to download gigabytes onto m system!
I’m not a fan of smoothing techniques, attractive though they may be to some people. If used it is essential to show the original data, as Roy has done, but I would really prefer the numbers.
Robin
It has just snowed overnight in some mountainous parts of Australia in the middle of summer!!! This is very unusual. So much for global warming. Where is it?
David L. Hagen (14:01:05) :
uh he’s smoothing over 13 or 25 months, not years..
How did I guess that Roy Spencer was referring to Doltoid?
Ern Matthews (14:33:15) :
100 yr. average of the last 2000 yrs would look like an ammo dump after it’s been hit… rounds going off in trends every which way. Just as soon as the MWP (substitute an El Nino for present timeframe) was expended, the trend of boxes of ammo popping off would eventually subside.
Re: David L. Hagen (Jan 17 14:01),
David, the averages are over months, not years.
Actually, 13 months is not a good choice since the average for a given month (say January) includes each month once except for the month six months earlier (in this case, July) which is represented twice. The twenty-five month average will include the current month three times and the others twice.
If the trends are not the same for various months, this can produce a slight distortion in the graph.
David L. Hagen (14:01:05) :
You might want to read that again – Spencer is using 25 month averages. If he switched to 22 year averages then we’d have to wait 11 years to see recent effects.
——–
I’m a little surprised the 25 month line is as close to the 13 month line as it is. It must come come from the effect of the 1:13 line using 13X the samples, but the 1:25 line only uses 2X more.
———
It’s disappointing so many people are quick to jump on the negative aspects of anything without much thought, researching, or testing; be it climate data or Google search results.
For this, people could just go to Wood for Trees (link above) and try out the smoothing on their own.
Ern Matthews (14:33:15) :
> I would like to see an 100 year average. I wonder what that would look like?
Of satellite data? It would be blank for another 70 years. Then it would be a point for the next year.
Re: RomanM (Jan 17 14:54),
In case I was not clear enough, the 13 month average will produce the distortion.
Speaking of increased Tectonic Activity in light of recent events:
http://quake.usgs.gov/recenteqs/index_map.gif
This is the most active I have seen California.
Something to truly get ready for, not the imagined catastrophic warming that registers a piddly 1.25 deg. F (.7C).
The data tampering here is obvious: Roy’s head is a little too big for his body. 🙂
Mariss Freimanis (14:38:57) :
I also see cooling since 1998. But some, from both sides of this issue, will say 1998 doesn’t count because that was El Nino warming. They should also quickly emphasize that the warming of 2009/2010 is El Nino warming.
Meaning that the warming of 2009/2010 doesn’t count either—according to their way of looking at it.
Global warming believers don’t want to emphasize that the current warming is El Nino warming because these slightly warmer temperatures has been the only good news they’ve gotten in years.
That good news won’t look so good to them when the quick cooling that comes after El Nino warming sets in.
Well by smoothing the curves it’s obvious Spencer is hiding the bumpyness. Just kidding Doc. 🙂
BTW when I look at those graphs I don’t see a gradual upward trend as suggested by the linear regression line. What I see looks more like a step function occurring at 1998, the El Nino year. Prior to that the trend is a flat line at approximately -0.05. After that it’s another flat line at approximately +0.25. Do you have any idea as to what would cause the earth’s temp to take a sudden upward step?
Why would it make a difference whether you used a 13, 25, or a 48 month average, when, as I recall from statements by Hansen and Jones that anything under 10 years is statistically insignificant? A 30 year trend isn’t even significant when you’re talking natural variability.
Oh…forgot. If it’s warming in 1 year, it’s significant. Cooling in 7 years isn’t. Like 1934 being ever so slightly warmer than 1998 being insignificant, but if 1998 is slightly warmer than 1934, it’s major news…and 1934 gets the Voldemort honor of not being mentionable.
Are personal preferencies allowed? The 13 month averaging, by emphasizing the 1997/1998 El Nino, shows that the effect was felt beyond the atmosphere temperature averaging. Apparently traces of the heat were noted far beyond its locality. It created one of the hottest months recorded. Granted this is not
necessary for an atmosphere temperature graph and either can easily be read.
Seems that when an El Nino creates the damage on Coral Reefs that this one did,
some marker of its passage should be left.
Perhaps like “Kilroy was here” for us oldsters.
Dr Spencer
Are you applying any weights to your averaging filters or are the straight unweighted boxcar filter averaging?
A straight unweighted moving average is pretty messy from a digital signal processing standpoint (do a fourier transform of a box car function & see how it rings) – which is introducing spectral components that are basically noise – thus reducing the Signal to noise ratio of the data. A better approach is to use a cosine weighted average over your filter time of interest – much cleaner, less ringy signal (better S/N).
Interestingly enough, with both filters you have applied, the resulting filtered data is pretty similar – both had filtered out the high frequency component in a similar manner & the residual low frequency signal tracks reasonably well – suggesting the power in the 13-25 month bandwidth is very low. Not sure what the physical significance of that is, just an interesting observation.
What does it matter whether there’s warming or cooling ? The issue is whether man can influence it any more than King Canute was able to influence the tides.
The satellite data is an excellent comparison to land-based temperature stations. There are still unresolved issues between land-based and satellite measurements.
The UHI issue won’t go away. The IPCC estimates it as 0.006’C/decade.
In a small contribution to the debate, a paper from Fumiaki Fujibe in Japan published in International Journal of Climatology in 2009 has some interesting results.
The results were based on analysis of over 500 stations from 1979 to 2006 with the stations providing hourly temperature data. The temperature data was analyzed against population density around the location of actual temperature measurement.
First, there was a clear actual warming in Japan during that period – around 0.3’C per decade. Similar to what the IPCC reports for northern hemisphere land-based measurements.
Second, there was a clear urban heat island (UHI) effect. This was around 0.1’C per decade in the larger population densities. And there was a clear trend of increasing UHI effect as pop. density increased.
The author also comments that during periods of less pronounced warming there will clearly be an issue of removing the UHI effect. I.e. against a 20th century increase of 0.7’C, a 0.1’C per decade artificial UHI issue will be a major problem.
See more at http://scienceofdoom.com/2010/01/17/urban-heat-island-in-japan/
It has just snowed overnight in some mountainous parts of Australia in the middle of summer!!! This is very unusual. So much for global warming. Where is it?
Reports here; http://ski.com.au/
Pictures here: http://hangwiththewang.blogspot.com/
Spencer made headline in a Norwegian paper;
http://translate.google.no/translate?hl=no&sl=no&tl=en&u=http%3A%2F%2Fe24.no%2Folje%2Farticle3465280.ece
Observe that Cicero loves the AGW theory.
John Hooper (12:35:59) :
John,
What most who post here think is that the globe may have gotten warmer, but we don’t believe that any link to C02 has been proven. We also don’t believe that trillions of dollars should be subverted to worthless causes that won’t accomplish a single thing they claim.
The thousand-odd emails and documents sort of point to the fact that there is at least a small conspiracy to hide the fact that the scientist who keep making the claim don’t have the evidence they need either.
This has been covered pretty fequently here.
JimB (USA)
I’ve noticed this tendency to smooth over intervals of length n years + 1 month. What is the basis for this? It still will include a seasonal signal, only dampened. Why not smooth over, say, 24 or 36 months? Then any temperature signal is season-invariant. If the purpose is to make the trend information most transparent, it strikes me that the most obvious choices for smoothing would completely remove the strongest systematic harmonic, namely the annual cycle.
I realise that these are graphs of the temperature anomaly, but it seems reasonable to assume that even in the anomaly data there should be a small seasonal signal — say (guess) higher variation during the transitions, near the equinoxes. I would wager that in any reasonable measure of smoothness, a 12k smoothing is smoother than the corresponding 12k+1 smoothing (k>0) even though it uses a smaller averaging interval.
Peter of Sydney (15:22:10) :
Sorry, Peter, it’s all California’s fault. You see, it’s been so darned cold in the N. Hemisphere this winter that the Pacific is rallying some help, and has called on El Nino for emergency relief thrusters. Unfortunately, it took some of your summer and sucked it over to the West Coast of the US, and is about to dump it’s watery load.
I’d like to think that when it’s winter in your half of the Earth that the favor would be repaid, but these Warmists aren’t known for sharing the joy of sunshine.