Perennially Puzzled Bob Tisdale is puzzling over global warming at WUWT - again (archived here). In a rare moment of insight, blog-owner Anthony Watts in the comments says:
March 7, 2014 at 6:36 am
Thanks Bob, a tour de force (or farce depending on how you look at it)
A tour de farce is about right. Bob has written one of his long articles that goes through several ideas before getting to his punch line. I'll set out his thought processes so you can see the flow:
Bob Tisdale doesn't believe "manmade-global-warming dogma"
One of the climate science community’s primary problems was a very basic message…an intentionally misleading message. That is, it wasn’t how it was communicated; it was the message itself.
Bob takes issue with scientists because they take it as a given that humans are causing global warming. Even after all this time Bob can't accept the physics of the greenhouse effect. Bob thinks it is "intentionally misleading" to accept that there is a greenhouse effect caused by particular gases in the atmosphere, which keeps Earth warm.
What would have happened if we hadn't been adding greenhouse gases to the air?
As if to prove his point that he can't accept the physics, Bob posted a whole bunch of charts and text from the AR4 and AR5 IPCC reports demonstrating that without anthropogenic influences (an increase in well-mixed greenhouse gases) surface temperatures would not have risen.
Here's an example, from AR5. Bob showed Figure TS.9 as static charts. I've layered the different parts as an animation, showing observations with all forcings, observations with natural forcings only and observations with greenhouse forcing only. The observations are the thick black line, the shaded parts (yellow/grey) are the model results:
|Adapted from Figure TS.9, IPCC AR5 WG1 report|
Instead of sitting back and saying "hmm...that makes sense" like any normal sane person, Bob says it shows no such thing. Bob reckons it doesn't prove that humans have raised global temperatures.
Bob Tisdale's illogical chain of unreasoning
Bob isn't disputing the warming. Strangely, it's not that he thinks that the scientists have missed a gigantic "natural" forcing either. What he seems to be arguing instead is that models can't model natural variation and there is some "oscillation" that the models are missing.
In other words, Bob believes the world is warming by magic. That this warming is "natural" and unforced.
Bob hasn't said so specifically (or not that I could find), but the natural conclusion is that Bob thinks it will cool down when this sudden, new "oscillation" has run its course.
Bob doesn't explain why his oscillation has never been seen before - at least not in the past 20,000 years. He doesn't explain why his "oscillation" first appeared with the rapid rise of well-mixed greenhouse gases. Nor does he say when his "oscillation" will peak and go into the down-swing.
There are too many gaps in Bob's line of argument to go into all of them in detail. I'll summarise:
- It is warming - Bob doesn't dispute global warming itself
- It is "natural" - Bob disputes the greenhouse effect. He doesn't accept the underlying physics. He refuses to believe that CO2 keeps Earth warm and more makes it warmer.
- It is an "oscillation" - Bob's "oscillation" is only one way. It never actually oscillates it only goes up and up and up. It only gets hotter but never cooler.
- It's caused by ocean warming - from unstated causes.
Bob Tisdale won't impute a cause to his magical warming
Bob gets as far as the fact that the oceans are heating up. That's as far as he gets. He doesn't provide any explanation of the cause of ocean warming. That's why anyone who bothers reading Bob's stuff comes away realising that he believes in magic. Whether it's leprechauns or witches casting a spell or pixies scattering magic dust over the oceans - Bob doesn't say. Any time he's asked point blank, if he answers at all, he just points to his blog or one of his "books", which of course don't offer any explanation either. (Anyone who manages to wade through Bob's tripe deserves a medal for suffering meaningless boredom for so long.)
After several hundred words and multiples charts from the IPCC, Bob got to his punchlines:
Unfortunately for the IPCC, the models they show with only natural forcings (the blue curves) do not present natural variability. The climate models employed by the IPCC cannot simulate naturally occurring, coupled, ocean-atmosphere processes that cause multidecadal variations in surface temperatures.
Bob goes on to write:
These variations are most evident in the surface temperatures of the Northern Hemisphere, and they are driven by the naturally occurring multidecadal variations in North Atlantic sea surface temperatures (known as the Atlantic Multidecadal Oscillation) and the naturally occurring multidecadal variations in North Pacific sea surface temperatures (not represented by the Pacific Decadal Oscillation/PDO data)....
Which "oscillation" caused warming of the past few decades?
Now at this point at least one of his readers should be scratching her head and asking which "naturally occurring multidecadal oscillation" is causing temperatures to keep on rising. It must be a very, very long oscillation because otherwise surface temperatures would be back to those of whatever is the period of the oscillation. If an oscillation lasted 30 years, then every 30 years the temperature would be the same. If the oscillation is 100 years, then surface temperatures today would be what they were 100 years ago. So, this is a very lo...o...o...ng oscillation - at least a hundred years long for half the oscillation - and it hasn't yet peaked let alone "oscillated".
Temperature varies naturally, duh!
Bob puts up some charts of sea surface temperatures that he says he's detrended and makes the startling discovery that sea surface temperatures vary with time - duh! (He doesn't say how he's detrended the data. I had a shot at replicating what he did and figure all he did was subtract a least squares linear trend.) Then he makes another leap of logic. Bob wrote:
As illustrated, the forced component of the models (the model mean) fails to produce the multidecadal variations in the sea surface temperatures of the North Pacific and North Atlantic Oceans. This indicates the sea surface temperatures of the North Pacific and North Atlantic are capable of varying over decadal and multidecadal timeframes without being forced to do so by manmade greenhouse gases and aerosols.
Of course sea surface temperatures are "capable of varying" over time. Does he think no-one but him has noticed that fact?
Bob didn't have to remove a linear trend to show that sea surface temperatures can vary. If it was the linear trend he removed then any variation from the linear trend is, well, a variation from a linear trend. Nor has he made any startling new discovery. Scientists, as well as you and me, know that there are longer and shorter ups and downs in sea surface temperatures. ENSO is a good example of a intra-decadal oscillation. The surface temperature of the Pacific in different parts, for example, fluctuates over more than one decade. Not necessarily to any particular regular time frame - but it does get warmer and cooler in different parts over time.
If Bob thinks that scientists don't know this, then where does he think he got his information from? He didn't go and take his own measurements, that's for sure. It came from scientists! In fact, in the Nature editorial that Bob quoted from right at the beginning of his article, it states:
The climate system consists of many natural cycles operating on differing timescales, and in combination they result in short-term natural variability. These can work to lower, or raise, the global mean surface temperature through heat uptake or release from the oceans, among other processes. There is a lot of uncertainty associated with these cycles that carries through to model representations and projections.
Did Bob think that part of the message was okay? I guess he did.
I sometimes wonder if Bob is assuming that global warming is linear everywhere always, including in the North Pacific and North Atlantic. I'd have thought he would know that water moves about for one thing. It moves up-down-north-south-east and west and everything in between, depending on ocean currents and surface winds. When it moves it carries the heat with it.
I've dashed off a chart of one of the areas he plotted, showing the sea surface temperature anomaly from the twentieth century average using HadSST 126.96.36.199 and CMIP5 tas mean (sea only) for RCP6 (that was the pathway that Bob chose, but I don't think it would make much difference which one).
|Data source: KNMI Explorer - HadSST and CMIP5 model mean (tas)|
I also plotted them both, after deducting the linear trend (least squares) for each. I don't see a lot of value in doing so, because as you can see from the above chart, the measurements wander around the linear trend a lot, and if you were to plot, say, the trend in the early years it would be different to the trend in the middle which is different to the trend in the later years. Without discussing what physical mechanisms are causing the changes in sea surface temperature at different times, just removing the long term trend doesn't tell you a whole lot. Anyway, here is the result:
I haven't learnt much more by deducting the linear trend although I suppose it shows up the linear-trendless variation more clearly :)
Both charts demonstrate that the CMIP5 ensemble is much closer to the observations from the seventies to now (2013).
One thing that Bob is assuming (I think) - erroneously, is that by removing the linear trend he is left with only natural forcings. Now that's odd on one count and wrong on another. It's odd if he thinks that. It's odd - because he doesn't "believe" that warming is anything other than natural. That is, he doesn't accept the greenhouse effect is real. It's wrong because humans also created smog and lots of aerosols, which can cause cooling. So by only removing the linear trend what remains is not necessarily all "natural". Nor is the linear trend itself necessarily all from greenhouse gases. In the early part of last century, for example, there was solar forcing that contributed to the rise in global temperatures.
What is the bet that the error in observations of sea surface temperature is much less since the 1970s, too? I mean, how do I know which would be a more accurate reflection of what actually happened between 1900 and 1980 in regard to sea surface temperatures, the model ensemble mean or the observations?
Prior to the 1980s measurements of sea surface temperature were derived from instruments on shorelines, ships and buoys. The first automated method of gathering sst was by measuring water flowing through the input ports of ocean faring ships. While this method obtained a significant quantity of useful SST data there were some shortcomings. The depth of the input ports of different ships can vary greatly from ship to ship. In a stratified ocean these different depths can have different temperatures. This method also resulted in rigorous sampling along major shipping routes but a dearth of information about the vast majority of the world's oceans.
Since the 1980's most of the information about global SST has come from satellite observations. Instruments like the Moderate Resolution Imaging Spectroradiometer on board (MODIS) onboard NASA’s Terra and Aqua satellites orbit the Earth approximately 14 times per day, enabling it to gathering more SST data in 3 months than all other combined SST measurements taken before the advent of satellites.
So, it could be that the model mean is a more accurate reflection of what actually happened to the sea surface temperature in that region in the early twentieth century - or it could be the observations are more accurate. Maybe a reader will comment on that. In any case, are they within one or two standard deviations of each other going back to the turn of the century? (I'm not going to do the sums, but a reader here might know.)
Shorter Bob Tisdale
Instead of Bob putting up lots of charts which contradicted his argument, and instead of putting up lots more irrelevant charts, and instead of writing lots and lots of words, Bob could have got his message across more clearly and succinctly if he'd just written:
I, Bob Tisdale, don't believe the physics of the greenhouse effect but I accept the world is warming. Probably by magical spells being cast in the ocean.
From the WUWT commentsBob's articles attract the sort of WUWT-er who doesn't understand a word he writes but is happy to be given the chance to say their piece, whatever that may be.
Philip Haddad says that it's not the CO2 that's causing the warming, it's all that burning in nuclear plants!
March 7, 2014 at 5:27 am
Why is it that people will acknowledge that fossil fuels are a major anthropogenic contributor to global warming, but never make the connection that fuels are burned for heat, and heat is what causes temperatures to rise. CO2 may or may not contribute. The heat emitted from our energy use is four times the amount accountable by the actual measured rise in atmospheric temperature. The rest of the heat affects land and water temperatures as well as melting glaciers at a rate of one trillion tons a year. Climate sensitivity to CO2 was established without factoring in the very real effects from heat and is meaningless. We are being subjected to the present permitting and licensing of more nuclear power plants in spite of the fact that nuclear plants emit more than twice the total heat as their electrical output.
Doug Allen says it's only half the cycles - he also accepts "half" the science: the surface temperature record:
March 7, 2014 at 7:25 am
In other words, they did not tune the models to the long-term trends of the Northern Hemisphere sea surface temperature datasets, which account for the multidecadal variations; they tuned the models to the recent high-trend period that represents only one-half of “cycles”.
This seems so obvious by just eyeballing the temperature reconstructions from 1850 or 1880 to present.
I have never understood how the IPCC or others could responsibly claim “observed patterns of warming, including greater warming over land than over the ocean, and their changes over time, are only simulated by models that include anthropogenic forcing” when similar periods of warming occurred prior to 1950 or 1940 or 1900 when the forcing was “natural variability.”
Why would anyone believe the model projections or the IPCC meme when such obvious, misleading modelling is used to perpetuate consensus at the expense of better understanding of a very complex climate system.
Despite Bob posting dozens of charts from the IPCC reports comparing what would have happened if only natural forcings were operating with what his happening with greenhouse forcing, JimS says:
March 7, 2014 at 7:25 am
The core problem of the AGW issue is that climate scientists used rising global temperatures from 1980 to 2005 as being man-made through mankind’s CO2 emissions; they never considered that such warming, minimal though it was in the historical context, was more than likely accomplished naturally.
rgbatduke, a physics lecturer from Duke, (ie arguably a "scientist") writes a very long comment as usual, saying an awful lot - in fact he keeps repeating his message and adding to it after he says (excerpt):
March 7, 2014 at 8:01 am
...Wait! I know, I know, call on me!
How about not presenting a “message” at all since that is not the job of a scientist, it is the job of a political demagogue or religious leader?
Perhaps the batty duke is practicing for a new vocation, that of political demagogue or religious leader :(
Larry Hamlin doesn't have a clue what Bob was going on about, but he adds his two bob's worth anyway and says:
March 7, 2014 at 7:36 am
Excellent analysis Mr. Tisdale. It clearly establishes the “tails we win, heads you lose” strategy of those already convinced that only man made actions drive global climate. All that need be done is to manufacture the science to support this position.
G. Karst bemoans the fact that fake sceptics can't win a trick and says (excerpt):
March 7, 2014 at 7:30 am
It seems for skeptics it is one step forward and two back.
Even the recent GWPF sensitivity report is now being portrayed as skeptics admitting we are wrong:
Here was one of the world’s foremost bastions of contrariness when it comes to man-made climate change, admitting that temperatures were actually rising in response to human emissions of greenhouse gases.
And according to the study, the 2C threshold of dangerous warming would be crossed later on this century.
Lewis and Crok challenge two very critical numbers that are included in the recent IPCC report, known as AR5, that found that global warming was “unequivocal” and humans are the dominant cause.
The deck is rigged and stacked against us. We think we are making progress but CAGW meme is very much alive and kicking… hardly threatened… I’d say.
Even the malaria issue keeps raising it’s head constantly even though generally refuted:
“We have estimated that, based on the distribution of malaria with altitude, a 1C rise in temperature could lead to an additional three million cases in under-15-year-olds per year,” said Prof Pascual.
When will this MSM nightmare end. I want to get off this MAD merry-go- round. GK