Guest Post by Willis Eschenbach
I chanced to plot up the lower tropospheric temperatures by broad latitude zones today. This is based on the data from the satellite microwave sounding unit (MSU), as analyzed by the good folks at the University of Alabama at Huntsville. Here are the results, divided into tropical, extratropical, and polar. I’ve divided them at the Arctic and Antarctic Circles at 67° North and South, and at the Tropics of Capricorn and Cancer at 23° N & S.
Figure 1. Satellite-based microwave sounding unit temperatures (red line) from the University of Alabama Huntsville. Blue line shows a loess smooth, span=0.4. Data from KNMI (NCDF file, 17 Mb)
So … is this something to worry about?
Well, let’s take a look. To start with, the tropics have no trend, that’s 40% of the planet. So all you folks who have been forecasting doom and gloom for the billions of poor people in the tropics? Sorry … no apparent threat there in the slightest. Well, actually there is a threat, which is the threat of increased energy prices from the futile war on carbon—rising energy prices hit the poor the hardest. But I digress …
What else. Southern Extratropics? No trend. South of the Antarctic Circle? No trend, it cooled slightly then warmed slightly back to where it started.
So that’s 70% of the planet with no appreciable temperature trend over the last third of a century …
What else. Northern Extratropics? A barely visible trend, and no trend since 2000.
And that means that 96% of the planet is basically going nowhere …
Now, that leaves the 4% of the planet north of the Arctic Circle. It cooled slightly over the first decade and a half. Then it warmed for a decade, and it has stayed even for a decade …
My conclusion? I don’t see anything at all that is worrisome there. To me the surprising thing once again is the amazing stability of the planet’s temperature. A third of a century, and the temperature of the tropics hasn’t budged even the width of a hairline. That is an extremely stable system.
I explain that as being the result of the thermoregulatory effect of emergent climate phenomena … you have a better explanation?
My best regards to everyone,
w.
PLEASE! If you disagree with what I or anyone says, QUOTE THE WORDS that you disagree with, and say why you disagree with them. That way we can understand each other. Vague statements and handwaving opinions are not appreciated.
DATA: All data and R code as used are here in a zip file.
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Franco,
Using your method, you’re going to get bad results. Consider this hypothetical:
If there is trend of 0 at the equator, and we have a perfect sphere where temperature trends rise by latitude fairly evenly, then let’s say extratopical (20-85) is 0.3C/decade and an even greater trend for Polar (60-85) at 0.5C/decade. The trend from 20-60 is going to be positive but less than 0.3C/decade. However, if you subtract the NoPol trend from the Extratropical trend, you’re going to get -0.2C/decade instead of something between 0 and 0.3C.
Do you see the problem?
Same with anomalies.
Look carefully at your chart and the polar one above it. They are almost perfectly inversely correlated – virtually mirror images except for the size of the variance. If you change the sign of the (20-60) anomalies you’ll get a better (but not perfect) result. Correlation will improve by nearly 100%.
If you changed the sign of the (20-60) trend in our hypothetical, you’d have 0.2C/decade, which is a much likelier answer.
barry says:
February 4, 2014 at 9:26 pm
Barry, I didn’t provide the exact numbers for the various zones specifically because I want people to use their eyes and their minds. Take a look at the trend for the tropics in Figure 1. Some people are obsessing over whether that is positive or negative. The answer is, it is far too small to make a difference.
Visually, just looking at Figure 1, I’d say the following:
Arctic: ~ 1.5 degrees in ~ 30 years, call it half a degree per decade
NoExt: ~ .6 degrees, 0.2° per decade
Tropics: too small to tell
SoExt: ~ .3 degrees in ~30 years, call it 0.1° per decade
Antarctic: too small to tell.
Here are the actual figures in the same order, in degrees per decade:
[1] 0.51
[1] 0.24
[1] 0.07
[1] 0.1
[1] 0.01
I read above that Tamino is accusing me of lying because he doesn’t like the scale of my graphs … guess he should learn to use his eyes. The graphs are perfectly adequate, as my estimates above show.
Like I said … I wanted to encourage people to use their eyes and their good judgement, and to stop obsessing over minuscule differences.
In any case, because we are indeed a full-service gas station, I’ve posted up the month-by-month figures for the five zones as a fixed-width text file called “UAH by zone.txt” here for your further enjoyment …
And just to make Tamino happy, here’s his expanded-scale view of the tropics:
It was terrifying there for a while, the tropical temperatures were going through the roof …
w.
Franco,
Using your method, you’re going to get bad results. Consider this hypothetical:
If there is trend of 0 at the equator, and we have a perfect sphere where temperature trends rise by latitude fairly evenly, then let’s say extratopical (20-85) is 0.3C/decade and an even greater trend for Polar (60-85) at 0.5C/decade. The trend from 20-60 is going to be positive but less than 0.3C/decade. However, if you subtract the NoPol trend from the Extratropical trend, you’re going to get -0.2C/decade instead of something between 0 and 0.3C.
Do you see the problem?
Same with anomalies.
Look carefully at your chart and the polar one above it. They are almost perfectly inversely correlated – virtually mirror images except for the size of the variance. If you change the sign of the (20-60) anomalies you’ll get a better (but not perfect) result. Correlation will improve by nearly 100%.
If you changed the sign of the (20-60) trend in our hypothetical, you’d have 0.2C/decade, which is a much likelier answer.
Barry,
I effectively computed (lower-higher) anomalies getting the inverse results and didn’t note the inverse correlation. Thank you for the advice. Franco
Thanks, Willis. Your results are similar to UAH, which is not unexpected and corroborative. Thanks, too for the text data. Much appreciated. I’ll tinker around with it in Excel.
Franco, you’re welcome. The way you had done it still seems intuitively correct, and I’ve kept mulling it over. My advice amonts to subtracting extratropical from polar, which seems intuitively incorrect. It’s been interesting to think about for someone with a very ordinary maths education.
barry says:
February 5, 2014 at 4:42 pm
barry and Franco, you can derive the individual results from the merged extratropical and polar sections. It’s a weighted average, done as follows. I’ll call the three portions polar, extratropics, and middle
First, you need the area of the zones. UAH divides it (from memory) into 20° to 85° for extratropics, and 60° to 85° for the poles. That makes the middle the zone from 20-60°.
Next, we need the areas. The area of a latitude zone bounded by latitudes A and B as a fraction of the global surface is ( sin(A) – sin (B))/2. So their polar zone 60-85 has an area of .065, the middle zone from 20-65° is 0.327, and the extratropics from 20-85° is the sum of those two, 0.392.
This means that the polar area is abut 1/6 (0.166, or 17%) of the full 20-85° extratropics, and the middle area in between the poles and the tropics is about 5/6 (.834 or 83%) of the total.
We know the average of the extratropical area 20-90°. We know the average of the polar area 65-90°. We know the areas. The average of the middle area is found from the equation:
(1/6) * Polar average + (5/6) * Middle average = Extratropical average
This solves to
Middle average = (Extratropical average – .166 * polar average) / 0.833
Regards,
w.
“barry and Franco, you can derive the individual results from the
merged extratropical and polar sections. It’s a weighted average, done
as follows. I’ll call the three portions polar, extratropics, and middle
First, you need the area of the zones. UAH divides it (from memory) into
20° to 85° for extratropics, and 60° to 85° for the poles. That makes the
middle the zone from 20-60°.
Willis,
Thanks for the accurate reply. I’ve prepared both plots and fit parameters
following your schema, with slightly different numbers due to the size of
the middle zone (you used 20-65°; the value is 20-60°, so not 0.166 but 0.199
or 1/5 or 20%). These files are here,
highlighted in brown.
My mistake was to think the data (it’s wrong, but let’s say
temperature) would refer to unit area (they speak about “grids”) at the given
altitude (e.g. low troposhere), something like the surface brightness
of the galaxies in Astronomy, so that I could add (subtract) all the data,
the area weights beeing provided by people at UAH and included into the measure.
Regards.
Franco