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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“Peter of Sydney (15:22:10) :
It has just snowed overnight in some mountainous parts of Australia in the middle of summer!!! This is very unusual. […]”
Must be Al Gore on vacation down under.
“Peter of Sydney (15:22:10) :
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/”
That’s insane. Mind you, being 18th January, 2010, summer, it’s ~25c in the inner west where I am right now. That’s pretty cool for this time of year.
I suspect the issue is the smoothing finishes earlier, and thus drops a little section of rising temps, of course the same would happen if it was a downwards trend, its just what happens when you use a longer average, but some people dont seem to even understand simple statistics!
Seems the alarmist are the ones being paranoid ;0)
[snip] Get a grip. ~dbs, mod.
This is a red herring if you ask me. I don’t think anyone argues that we are warmer over the past 30 years, but that we are about as warm as the 1930’s, and the amount of warming has levelled off over the past 10 years.
The main issue with the satellite data is of course buried with this discussion. Are measurements at 14,000 ft (near surface) really relevant to surface temperatures. January is the warmest month on record in 30 years according to the unadjusted satellite data And even if it is relevant, who cares, the main issue has always been what is causing the small amount of warming we have experienced.
I still have not read anything of substance showing in a conclusive manner that mans CO2 is responsible for all or most of the warming. Correlation does not prove causation. I think you could show warming is correlated with the number of runs scored in the MLB season.
It was cold in the 60’s when runs were hard to come by, and warm in the 90’s when steroids caused balls to fly out of the park and runs were scored aplenty before levelling off in the last few years. Perhaps warming is related to steroid use?. I suppose warmers would say juiced players exhale more CO2. Or is it colder weather suppresses runs and warmer weather enhances runs, or none of the above. Maybe we should tax MLB tickets and players if we can show they are responsible for global warming. LOL.
Dr Spencer: I believe the accusation had to do with the fact that the 25-month average tends to miss most of the recent rise in temperatures since 2008. However, I agree such an average does reduce the 1998 spike and that any claim regarding your motives for changing the averaging is just pure speculation on the part of the bloggers involved.
DirkH says:
Because the ups-and-downs of the climate from year-to-year depend sensitivity on the initial conditions. However, the basic response of the climate to a radiative forcing does not when one looks over a long enough period of time that the trend is dominated by this rather than by the year-to-year variability.
Think of it this way: If I told you that I could predict that the weather here in Rochester on July 4th will be partly cloudy with afternoon shows and highs in the mid-80s, you would rightly ignore me. Even if I predicted that July would be much cooler than normal for July, you would probably be skeptical. However, if I predicted that the climate in July would be somewhere in the neighborhood of 25-30 C warmer than the climate in January, then you would probably admit that this is a reasonable forecast. Some things are easily predictable because they are robust to small changes in initial conditions; others are not.
What the GCMs do predict, by the way, is that under scenarios of steadily increasing greenhouse gases, it will not be uncommon to be able to identify periods of 10, or even 15 years, in which the least-squares linear fit temperature trend is negative. See here: http://www.esrl.noaa.gov/psd/csi/images/GRL2009_ClimateWarming.pdf
As I noted, you are mischaracterizing what sort of correlation is expected, as studying the GCMs’ output clearly shows. Think of it this way: Do you think that the fact that it is not uncommon to have weeklong periods here in Rochester in April where the temperature trend is negative disproves the notion of the seasonal cycle (which predicts there to be a positive trend in April)? These concepts are not that difficult to understand if you open your mind and think like a scientist instead of an ideologue.
“Peter of Sydney (15:22:10) : 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?
No wonder there are strong gusty cold winds in Canberra today. We are north east of these mountains.
0.8 degrees over 20 or so years is insignificant both physically and statistically when compared to natural climate variability.
I can not see why anybody is concerned about 0.8 degrees over 20 years of observation.
Please explain why we should care about such a small change when much larger changes occur naturally.
A recent article suggested that the idea of a global average temperature was a bit ‘meaningless’. Due to the high temperatures in the southern hemisphere January could be one of the warmest months on record! But it’s a bit like measuring the temperature of your cooker, kettle, fridge and freezer and calculating the average.
Would it be possible/useful/interesting to split it into two data sets, one for each hemisphere?
One more thing, the charts a mess. Satellite measurements began in 1979, you can not have a 25 year average until 2004.
The line is drawn from a trough, while 0 is 0.2 deg C higher the following year, making the slope higher. How was a 25 year average or even a 13 year average calculated in 1980 without using surface measurements going back to 1955 or 1967 (they then would have to estimate how those surface temperatures translate to 14,000 ft), both of which serve to increase the slope since it was colder in those years and make it look like more warming from 1979.
There should be no running average for satellites until 2004, and the anomaly should be based on a 25 year average from 1979-2003 as well, and then we will see how much warming (cooling) there has been. Of course, 6 years is meaningless when talking of climate, but it would show a clear cooling or at least non-warming trend, but the chart should be good for years to come as more data is added.
What I cant understand is why we keep on looking at a 30 year satellite record when we know the 1970s where if not the coldest decade in the 20th century very close to it. Now if we really wanted to look for a serious warming or cooling trend would we not at the very least look for a time frame that included both the warming and cooling faze of the pacific decadal ocillation . Why dont we go back to say 1940 to present and see how much warming or cooling there is.
pft
Its a 25 month running average, not 25 year.
pft says:
That may be one good reason why he chose a 25 ***MONTH*** average instead.
Oh the irony! On this day, 18 Jan 2003, we had the firestorm in Canberra when nearly 500 homes were burnt, four people died and hundreds were injured. The current official temperature as at 11.30 am in Canberra today is 15.6C!
I’m sorry, but I don’t see that trend line at all.
From ’79 – ’98, I see a flat line that looks like an average temp a little below
the 0.0 base line. Something like -0.1
I see the spike between ’98 – ’99
Then a flat line again from ’02 – ’07, which just looks like left overs from the
’98 – ’99 spike
I hate using these stupid trend lines. For one thing, it makes people that are using them try to prove a point, and for another, it gives the impression that
it will just keep going up until we all burn up.
OK, so the earth has warmed a little. The *real* questions for the climate catastrophists are:
1. Was the warming caused by natural variation due to oceanic, solar, and galactic cycles? If not, can you measurably subtract the natural variation from your claims of human-caused temperature increases?
2. If CO2 had any measurable part in the warming, what measurable component of that part is due to a tagged, measurable, human contribution to the observed CO2 concentration increase?
I understand the satellite data is not calibrated from ground stations…but there surely must have been some calibration work done with aerosondes balloons etc at some point?
My understanding is that the data needs to be adjusted for changes in emissivity of the earths surface – it is easier where the emissivity changes little. This January with such wide snow cover the emissivity must have changed fairly substantially in the NH so i wonder how they calibrate a reading with rapidly changing emissivity and how they calculate the correct emissivity for a given data point on an hour by hour and day by day basis.
Is anyone aware of the emissivity data that goes with the raw data?
I have not read past Lubos Moti’s post of 17Jan 12:35:07 so someone else may have replied.
The emissivities of water and ice based on NASA Modis UCSB library data (http://www.icess.ucsb.edu/modis/EMIS/html/em.html ) in the infra-red range of wavelengths 3 to 15 are in excess of 0.96 ie water and ice are close to black bodies. Ice reflects at UV and visible light wavelengths (note need to protect eyes and skin from sunburn on skifields)
Ice, snow and water will radiate heat to space through the atmospheric infrared window particularly at the poles where the air is very dry.
I have suggested before that “forcing” is not a sensible term. The driver of heat transfer is temperature difference. The driver of mass transfer is concentration difference which can be expressed by partial pressure differences. The term “Albedo” is meaningless in considerations of heat and mass transfer. Clouds of water and ice molecules will absorb radiation both from the sun and the surface and will re-emit the energy in all direction including space. The density of clouds varies. Some “black” clouds will even absorb most visible light.
Understanding of climate will be improved if people stopped using jargon. Accountants and lawyers use jargon to confuse and make themselves more important. There is no need for real scientists and technologists to use jargon in discussing climate unless one is a pseudo scientist spinning information to hold onto a job.
If anything, the 25-month smoothing shows a slightly more upward trend than the 13 month. And it shows your critics are absolutely clueless.
Thanks for the post, Doc.
Perhaps the alarmists would like some cheese with their whine(s) ?
GeneDoc
“uh he’s smoothing over 13 or 25 months, not years.”
Thanks for pointing out my error – haste makes waste.
David
Louis Hissink (12:31:56) :
Ditto. I was in college in mid 70’s also. That change in science had not quite filtered into most of my core physical science classes yet and I’m greatly thankful for that! I could never learn science by what I read today.
[snip] Maturity is a virtue. Please lighten up. ~dbs, mod.
.
So like the above graph shows that there has been global warming.
You dudes here are totally hell bent against any possiblity that humans have in any way contributed to this.
SO
what has caused this warming? eh?
can you provide quantitative analysis that show where this warming has come from?
all I see from you dudes are comments like “oh its natural” but to me thats like telling me that God exists. ie a viewpoint biased by preexisting prejudices.
have any of you dudes calculated how many joules of energy have been inserted into the biosphere by the burning of “buried sunshine”? HM? like maybe that can cause some heat eh?
you dudes complaining about the fact that science being taught in schools is not what is was like when you were there in the 70’s. Toke on bro.
So like, have you gone back to school now for 4 years to refresh your degree, and thus provide a realistic comparison to your “oh the good ol days were better”
It looks like a .3 C step change in 1998 and nothing else. I wonder why there is a step change there? Are we certain we don’t have a sensor or program reason for the step change?
So much of the data has been so badly mangled, modified, deleted and fudged from everyone else I don’t bleieve anything anymore.