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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David Gould says:
August 23, 2010 at 1:13 am
Stevengoddard,
“So you are saying that unless I know who killed person A, I cannot possibly know who killed person B? I think that there might be something in error about that logic …”
Well some people have already shot your analogy, but I have a different interpretation.
We know person A and B were killed using the exact same M.O. (ie +0.5 degrees warming). We suspect that person C killed B (ie. CO2 caused the 1975 warming). We know C could not have killed A cause he has a bulletproof alibi (ie CO2 was much lower in 1910).
Does that mean we arrest C and we have any kind of chance of a conviction? I suspect any decent lawyer would win such a case. Maybe we should find who killed A and see if he had any reason to kill B also.
Bob_FJ
Try using Fourier Convolution, or Spectral Filtering, it covers the end points, as compared to standard averaging. This graph used a 40 yr. low pass filter.
http://www.imagenerd.com/uploads/hadcet-raw-filtered-QDnyw.gif
Robert,
compare this to Tamino’s East England Projections. The lower filter shows a Fourier Convolution filter of both the East English & Hadcet data. This also used a 40 yr. low pass filter.
http://www.imagenerd.com/uploads/lt-temp-1650-2008-1-Rxrdy.gif
@GeoFlynx I doubt that any serious scientists on this site will disagree that an increase in carbon dioxide does give you a net increase in temperature. The question is the magnitude of the forcing. The models I have examined give you a change of 0.00125 to 0.00250 degrees C per ppm with a decreasing effect as the CO2 concentration increases (logarithmic). The question is several fold. First, has there been much real change since the 30s in rural temperatures. The answer I get is very little. The urban heat islands have nothing to do with CO2 and have indeed warmed. Secondly, the question is one of the honesty of the brokers in this game. From my experience, most of them are rent-seekers who are trying to justify their windmills, solar panels, etc. on the basis of AGW. Thanks but no thanks. I do have a 10KW solar installation and a a full electric car that can go 70 mph, and heat my house by burning sawdust wood pellets, so its not like I am a guy who is opposed to alternative energy. I am just opposed to academic dishonesty.
GeoFlynx
What do you believe caused the 1910 warming?
@GeoFlynx 7:08
Please see my last post immediately above yours.
Here is my version of the ultimate cherry picking endeavor. Pick only ENSO neutral years to study land temperature. Given that there is a lag for tropical SST conditions to affect extra-tropical land temperatures, it would be worth while to run several temperature series from the data sets available, one right on neutral conditions, and a set that is delayed by 1, 2, 3, 4, 5 years, etc. Consider nothing else for this run. Then do the same for the various Atlantic Oscillation System years, and PDO years. In other words, work only with temperature series not affected by natural variation outside neutral and the lag affects already well known. Averaging through positive and negative phases plus their lags ruins the data for CO2 global warming purposes.
@ur momisugly GeoFlynx
Whereas your position would be Anything But Cycles?
PDO, NAO, AMO, ENSO.
Dominic
GeoFlynx says:
August 23, 2010 at 7:08 am
I think that everyone knows that AGW is an acronym for “Anthropogenic Global Warming,” as it is often used in this blog to describe a theory of climate change. After reading many of these posts, ABC or “Anything But Carbon” might be a good fit to define this site’s opposing view.
Actually, it’s more like APC – Any Possibility Considered. “Carbon” simply hasn’t been shown to have caused much of the recent warming, nor indeed to have been the cause of any warming historically. But, perhaps you have evidence to the contrary.
ShrNfr says:
August 23, 2010 at 7:32 am
Very well said! I think this is an excellent representative post for many of the sceptics visiting this site!
-Scott
Scott says:
August 23, 2010 at 3:47 am
re: Julian Flood August 23, 2010 at 1:25 am
quote
Is there data (yes, yes, I know, it’s a collective noun in layman speech) about variation in aerosols? Not modelled ‘data’, real data. TIA.
To my knowledge, no one cared about aerosols back then. They started caring after the London smog episode of 1952 killed a bunch of people. Thus, I doubt anyone can make good estimates of aerosols from back then, and there likely isn’t any sort of data that’s even close to useful.
In general, human-caused aerosols probably went down per person as we got cleaner/more efficient, but at the same time the population went up, so…?
unquote
So without the data the supposition that warming was suppressed by aerosols is opinion, not science. If you gave me carte blanche to tweak the graphs with forcings of plus or minus 1.75w/m^2 between 1910 and 2010 then I suspect I could get a better match with the statistics of petrochemical output vs temperature (to use one example).
JF
“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.”
_________________
I think you’re on to something. We may have reached the point of deminishing returns in the battle with co2 and temp-wise it may not be giving us anymore BTU’s in the future. I also have a sneeky feeling that during the course of glacial periods we don’t have La Ninas and El Ninos but rather El Ninas and La Ninos, know what I mean?
Joe D’Aleo, Professor Easterbrook and myself have at different times referred to similar repeating past warm and cool periods back in April 2009
1900-1925 COOL- AMO AND PDO BOTH NEGATIVE OR COOL
1926 -1944 VERY WARM – AMO AND PDO BOTH POSITIVE OR WARM
1964- 1976 VERY COOL- AMO AND PDO BOTH NEGATIVEOR COOL
1994 2007- VERY WARM- AMO AND PDO BOTH WARM [so called global warming period
2009 – COOL- AMO AND PDO BOTH NEGATIVE OR COOL
http://icecap.us/index.php/go/joes-blog/amo_and_pdo_the_real_climate_makers_in_united_states/tland.org/bin/media/newyork09/PowerPoint/Don_Easterbrook.ppt
steveta_uk says:
August 23, 2010 at 3:26 am
“If 300-310 ppm caused a 0.5C increase, and 340-390 ppm caused a 0.5C increase, and the effect of CO2 concentration is known to be logarithmic…….I suspect the required increase might be quite high.”
Correct, the IPCC A1F1 assumes enormous CO2 emissions increases. While enough coal actually exists to create those emissions, the fact that the price of coal has more then doubled in most of the world in the last 5 years leaves a question as to whether digging that much coal out of the ground would be economically viable. I.E. At $100/ton for coal nuclear is cheaper, at $400/ton for coal solar panels are cheaper.
The price of a ton of coal delivered on the US Eastern Seaboard has gone from $40/ton in 2005 to more then $80/ton today. The price of a ton of delivered coal in Europe is running right at $100/ton and the price in the Asia Pacific is more then $100/ton.China went from $27/ton in 2002 to $116/ton today. With the exception of the US Midwest(coal in Wyoming sells for $12/ton) if all one cares about is their wallet then building a coal fired electricity plant is financially foolish.
For the cycle fans: Why don’t the cooling phases equal the warming phases?
The “carbonated cherry” looks a lot like a non-carbonated cherry from the MWP…
Moberg (863-997) v HadCRUT3 NH (1976-2010)
Over what sort of time period?
The climate has been warming on the ~1,500-yr cycle since
I fat-fingered the “Enter” key!
Over what sort of time period?
The climate has been warming on the ~1,500-yr cycle since about 1600 AD. The warming phases of the shorter cycles have had higher average amplitudes than the cooling phases since about 1600 AD. It was the other way around from about 1100 AD to 1600 AD – The cooling phases had higher amplitudes.
The ~1,500-yr cycle is known as the Dansgaard-Oeschger in the upper Pleistocene and as the Bond cycle in the Holocene. It has a variability of ~500 years. It can be as short as 1,000 years or as long as 2,000 years. It had a 15-20C amplitude (in the Northern Hemisphere) in the Pleistocene and a ~2C amplitude in the Holocene.
@Yuba Yollabolly
Because the underlying trend is a rise in global average temperatures. This is suggested to be the ongoing recovery from the LIA.
Roughly speaking, if you look at the trend 1850 – 1950 (when CO2 was still below 300 ppmv and not therefore a significant component of the various temperature forcings), you get +0.5C per century.
Extend that trend from 1950 – present and plot the sine of ~30yr warming and cooling periods riding up the slope and you have your answer. The amplitude of the cool phases is reduced by the rising underlying trend.
Dominic
I don’t have time right now, but it would be interesting to regress annual CRUTEMP on CO2 (or log CO2), with a simple Santer/Bartlett AR(1) se adjustment. The correlation is obviously positive, but it won’t be nearly as significant as CRUTEMP on time, since CO2 is pretty flat before 1950, while CRUTEMP has the Goddard Warming Spell.
Hi David Middleton, thank you for your reply.
Actually I was thinking since the industrial revolution – roughly the period of the main graphs (above).
Although the timing would be reasonable for a Bond event…aren’t Bond events cooling events?
Thanks
I completely agree. What is real? Raw instrument data is not adequate, by itself. DOES need to be adjusted, to account for TOB changes. UHI does absolutely need to be adjusted for – but not with one global adjustment; each station needs to have its own (too much work? tough). Proxies DO need to be homogenized, so that they can be assembled together sensibly. Tree rings DO need to have the temperature factor identified and isolated, apart from humidity and other local conditions. Ice cores need to have their time element de-subjectified.
Climatology is a terribly new science, with records that only go back a short time. Proxies have too many assumptions underlying them for long-term past histories to be looked at as predictors of the future. M & W 2010 spells this latter out clearly.
I look at GHCN station records and realize how SHORT a record we have – even the long term ones.
It is simply too new of a science and too short a record to be able to claim what they have claimed. And that is all exacerbated by the assumptions, data tainted by improper instrument locations, data left out, dying off of 80% of the world’s met stations, lack of inclusion of statisticians, and poor methodologies. Those are a LOT of weaknesses in the work done thus far.
The EFFORT to compile globally averaged temps going back any number of years is an admirable one – for information purposes. I give Mann and others a lot of credit for having done so. But any conclusions AT THIS TIME need to be – at best – tentative. The data and methodologies need to be proven out much MUCH more, over time. And to extrapolate from the hodge podge that exists? It’s basically just laughable. And anyone BELIEVING such extrapolations cannot possibly be using the left side of their brains.
BBD-
Hasn’t the general trend for the last 10ky has been one of cooling?
Thanks
Yuba says:
Hasn’t the general trend for the last 10ky has been one of cooling?
Yes, but you are looking at the big picture. The recent past (~1200 years BP) has seen both warming and cooling episodes. As I suspect you are perfectly well aware.
Dominic
@ur momisugly Yuba
Yuba says:
Hasn’t the general trend for the last 10ky has been one of cooling?
Yes, but you are looking at the big picture. The recent past (~1200 years BP) has seen both warming and cooling episodes. As I suspect you are perfectly well aware.
But please don’t feel obliged to take my word for it. Here’s what Keith Briffa thinks:
Briffa: 22 September 1999: 938018124
‘I know there is pressure to present a nice tidy story as regards ‘apparent unprecedented warming in a thousand years or more in the proxy data’ but in reality the situation is not quite so simple. [-] I believe that the recent warmth was probably matched 1000 years ago. I do not believe that global mean annual temperatures have simply cooled progressively over thousands of years as Mike [Michael Mann] appears to and I contend that there is strong evidence for major changes in climate over the Holocene (not Milankovich) [sic] that require explanation and that could represent part of the current or future background variability of our climate.’
(I don’t comment here enough to know whether the link will land me in trouble?)
Source: http://www.eastangliaemails.com/emails.php?eid=136&filename=938018124.txt
The Bond events are episodes of sharp cooling interpreted from periodic increases in the volume of ice-rafted sediment in North Atlantic cores.
Each cooling event is followed by a warm-up. The last Bond event was around 1600 AD. This is also coincident with the coldest part of the LIA on Moberg’s NH reconstruction, Alley’s d18O ice core temp’s for Central Greenland and Keigwin’s d18O temps from forams in the Sargasso Sea.
We’ve been warming on that ~1,500-yr cycle since 1600. There is a roughly 60-yr cycle “riding” on the 1,500-yr cycle. As long as we are on the “up slope” of the 1,500-yr cycle, the 30-yr warming phases of the 60-yr cycle will generally warm more than the 30-yr cooling phases will cool.
We could be in the warming phase of the 1,500-yr cycle for the next 100 to 900 years. Although Alley’s ice core temperatures seem to have an 800-yr cycle with about a 2C amplitude. If that cycle is meaningful, we are very close to the end of the Modern Warming.
GISP2 w/ HadCRUT3 3kya
Yes and it still is… At least in the Northern Hemisphere.
I scaled the HadCRUT3 NH temp’s to Alley’s Greenland ice core temp’s here:
GISP2 w/ HadCRUT3 10kya
And to Keigwin’s Sargasso Sea temp’s here:
Sargasso w/ HadCRUT3