By Steve Goddard
My friend Tamino says that “the modern global warming era starts in 1975.”
He goes on : “It’s an estimate of the time at which the trend in global temperature took its modern value.”
As you can see in Phil Jones’ HadCRUT graph above, the 25 year period from about 1975 to 2000 did warm about half a degree C.
You can also see that the 30 year period from 1910 to 1940 similarly warmed about half a degree C. At that time, atmospheric CO2 averaged about 305 ppm, well below Dr. Hansen’s suggested “safe level” of 350 ppm. See the graph below for that period:
Here’s an annotated HadCRUT graph to help you see the relevant periods and the changes of temperature versus changes in global CO2 concentration during the same period:
The video below superimposes the 1975 warming (blue line) on the 1910 warming (black line.) Note the similarity in slope, duration and patterns. It would be difficult to explain the 1910 warming as being due to CO2, because CO2 was barely above pre-industrial levels and rose only 10 ppm during that period.
Given the similarity between the 1975 warming and the 1910 warming, it is irrational to blame the 1975 warming entirely on CO2. The practice of good science tells us to look for a hypothesis which can explain both similar warming periods.
If there is an influence of CO2 in the recent warming, it appears small. And the warming stopped ten years ago, as shown in the HadCRUT graph, despite rapid increases in CO2.
Or perhaps one might conclude that climate sensitivity has decreased as CO2 levels have risen. In 1910, with CO2 at 300 ppm, it only took ten additional ppm to raise temperatures by 0.5°C. By contrast, in 1975 it took about fifty ppm more to produce the same 0.5°C warming by the year 2000.
There were also periods of time with rising CO2, and little or no rise in temperature. From 1940 to 1980, there was no net warming while CO2 rose by 30 ppm. Since 1998, there has been no warming – as CO2 levels have risen 30 ppm.
I feel a chill of La Niña coming on.
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Don’t know about the warming that ended in 1940 on the graph below (note how adjusted down it has been compared to what it was just ten years ago), but the post 1975 warming can be explained by the near simultaneous peaking of the AMO and PDO and UHI.
If Cosquer Cave is any indication, it started nearly 30,000 years ago. And it is a very good indication.
“I feel a chill of La Niña coming on. ”
Indeed. People are murmuring about the upcoming winter, and the feel of fall in the air.
They have not forgotten the late end of winter, and it’s on thier faces.
Nobody is listening to the global warming trumpets.
They are looking at the sky, the brightness of day, the plants & animals.
We may be at ground zero of La Nina.
If the argument was that CO2 was the only driver of global temperature, the ups, downs and flatlines would show that argument to be false. But, given that that is not the argument …
It’s almost a perfect fit,
1880 to 1910 and 1940 t0 1970 all in the cooler mode!!!!
warm
1910 to 1940 and 1970 to 2000 warmer
I can’t believe the slopes match even the wiggles are the same!
Wow!
good post Steve Goddard!
My friend Tamino says that “the modern global warming era starts in 1975.”
thank you Tamino! for getting Steve to put the graft together.
The interesting thing is how are we flat lining for 10 years? 2000 to 2010?
faulty data? uhi? momentum is higher? solar activity was higher? 6-10 year lag?
pass the popcorn Vince Causey, while the corn grows!
The stupidity of this is beyond belief. How can the global average always be under the average until Warmists decide it is over? This is not science. It is not real. It is some sort of game.
Tamino…..1975…..
Huh, odd year to chose, because isn’t 1976 when the Great Pacific Climate Shift happened? I’m just askin’. Dang, must… have been…. an……um…. coincidence. How could Tamino have known?
(sarc off) (btw, do Carbonated Cherries have more flavor?)
2:32 video,
Chris de Freitas Ph.D, on El Nino and La Nina prevalence, which influences temperatures one way or the other:
By getting you to focus on the increase from 1975 to 2000 they can hide the decline thereafter
Steve
I agree with your post, here are the trends for the graph.
Nearly identical global warming rate of about 0.15 deg C per decade for the periods from 1970 to 2000 and 1910 to 1940:
http://www.woodfortrees.org/plot/hadcrut3vgl/from:1910/to:1940/compress:12/plot/hadcrut3vgl/from:1910/to:1940/trend/plot/hadcrut3vgl/from:1970/to:2000/compress:12/plot/hadcrut3vgl/from:1970/to:2000/trend
Zero global warming rate since 2000:
http://www.woodfortrees.org/plot/hadcrut3vgl/from:1998/to:2010/plot/hadcrut3vgl/from:1998/to:2010/trend
rbateman says:
August 22, 2010 at 9:48 pm
“I feel a chill of La Niña coming on. ”
Indeed. People are murmuring about the upcoming winter, and the feel of fall in the air.
They have not forgotten the late end of winter, and it’s on thier faces.
Nobody is listening to the global warming trumpets.
They are looking at the sky, the brightness of day, the plants & animals.
We may be at ground zero of La Nina.
______
Could we call this La Nina alarmism? Here in Denver, where we were just one degree shy of a record high for August 22, at 97F, the only thing I saw on people’s faces were some nice suntans, and smiling neighbor kids playing in their pool. La Nina will come and go, and no ice age will ensue.
David Gould says:
August 22, 2010 at 9:55 pm
If the argument was that CO2 was the only driver of global temperature, the ups, downs and flatlines would show that argument to be false. But, given that that is not the argument …
_____
Thank you David for a wee bit of….Perspective!
To be quite blunt, I don’t think we have a clue if temps are even up over the last 35 years. After pouring over the Surface Station project I have very serious doubts that the temperature record is anywhere close to accurate. With every possible error biased to the upside I’m amazed that temps are down over the past 10 years. Until we actually figure out how to record a temperature accurately I don’t think we can say much of anything about temperature trends.
Other forcings play a role besides CO2, and prior to 1980 it’s generally agreed in the climate community that sulfates balanced CO2. Hence Tamino’s comment about the “modern warming period starting in 1975”. Also, don’t fall into a trap of expecting CO2 and temperature to rise in lock step in any case… it’s a slowly changing secular forcing, and there are other, natural sources of climactic variability that over any short period will tend to overwhelm this slowly changing secular forcing.
Steve says that “The practice of good science tells us to look for a hypothesis which can explain both similar warming periods.” Yes, the simplest reasonable hypothesis is that total forcings increased for both periods, causing net warming. With a complex system, it’s not reasonable to assume all but one forcing is constant over a both periods. Regarding the similar values… coincidence happens in science all of the time, it’s why we do more than two tests in experimental measurements before making our conclusions.
Warren Meyer of climate-skeptic.com deserves some credit, since he has pointed this out repeatedly. (For example, http://www.climate-skeptic.com/2010/03/oh-maybe-ocean-occilations-are-important.html)
The IPCC says: “Modelling studies are also in moderately good agreement with observations during the first half of the 20th century…” “Moderately good agreement” means that climate models totally fail to reproduce the temperature peak around 1940. Actually, the diagram of models vs. temperature is quite revealing if you have an ounce or two of skepticism.
In other words, the IPCC has basically glossed over this problem.
David Gould
If you can’t tell me specifically what caused the 1910 warming, then you can’t claim to know what caused the nearly identical 1975 warming.
Tim L says:
August 22, 2010 at 10:06 pm
The interesting thing is how are we flat lining for 10 years? 2000 to 2010?
faulty data? uhi? momentum is higher? solar activity was higher? 6-10 year lag?
I wouldn’t know all the reasons but flat temps have happened before
http://img837.imageshack.us/img837/1992/zzznature06982f12crop.jpg
Carrick
Same for you. Explain specifically what caused the 1910 warming, and why it was not also responsible for the nearly identical 1975 warming.
Steve Goddard, nice work proving Phil Jones wrong using his own graph data!
Or perhaps mid seventies was just about the time, ‘all the weather stations migrated south’ or the ‘pump up the volume’ really took off.
Reading Ross McKitrick demolition of GHCN records was an eye opener and I don’t think that what any of these guys say, argues over, or for that matter does – I ain’t going to believe it.
La Nina, coming (now here), ENSO fading….all reasons to kick this into where it belongs, file under – “nothing to see here.”
Its all about the ocean currents, stoopid – not forgetting, big yellow thing (fusion reactor) in the sky.
Giss model E forcings suggest that the warming between 1910 and 1940 was caused by roughly equal parts of increase in solar activity, increase in Co2, and reduction in aerosols (i.e. volcanos early in the period, and an increase to no volcanos late in the period).
Here’s a link for earl 20th Century warming http://www.skepticalscience.com/What-caused-early-20th-Century-warming.html
Warmists are in trap, concerning the 1910-1940 warming. It can not be caused by CO2, so they have to admit natural causes, like ramp up in the sun activity from 1910 minimum. But at the same time, they claim the sun has very low effect on temperatures, where mechanically applying the 0.1% fluctuation in TSI. Cooling period 1940-1975 is a problem as well, though they managed to erase it from global datasets, but it appears pronounced in NH record.
“Global” datasets stink. We do not know much about southern half of the globe – prior 1950 – and by data infilling, “decreasing the 1940 blob by 0.15 deg C”, statistical plays with buckets, station cherry-picking, manufacturing trends without much data in tropics and central Asia they almost managed to erase the cooling period and inflated the post-1975 warming trend. For HadSST2 dataset alone, there is an inexplicable step increase of global SST by 0.1 deg C since 1998, which makes another +0.07 deg C for global HadCRUT.
Northern extratropics have the best coverage history and Atlantic has the most data since 1900. I take this as UHI-free NH temperature proxy any day.
http://climexp.knmi.nl/data/ihadsst2_280-360E_0-90N_na.png
The HADCRUT graph shown in the lead article is rather misleading. They use a 21-year moving simplified Gaussian smoothing average, (10 years each side of the target year), which means that there is no actual data available for determining it over the final 10 years, and the algorithm should thus stop short at 1999. However, someone has extended the black line in a way presumably that they would like to see it go. On the other hand, the following modified image seems to be a better averaging to me, as an eyeball job, and it then looks somewhat similar to the plateau around 1940! Oh dear!
http://www.flickr.com/photos/26175880@N05/4919342326/
PDO, PDO, PDO
Otherwise called the Elephant in the AGW Looney Tunes story.
JC
Michael Hauber, Reur August 22, 2010 at 11:37 pm
Would you care to quantifiably elaborate on your claims please, with adequate references?