Saturday
Jul162011
by 
Bishop Hill
Bishop Hill Warm climates of the past
Jul 16, 2011 Climate: MWP An interesting looking conference at the Royal Society in October:
Warm climates of the past - a lesson for the future?
In several periods in Earth's history, climate has been significantly warmer than present. What lessons about the future can be learnt from past warm periods? The answer depends on the quality of reconstructions of past climates, our understanding of their causes, and the validity of climate models which aim to reproduce them. This meeting will address these exciting and challenging issues.
Reader Comments (24)
"... past climates, our understanding of their causes, and the validity of climate models which aim to reproduce them"
My understanding is that climate is now regarded as chaotic non-linear, so trying to understand past cycles is pointless
Of course, if it actually is chaotic non-linear, trying to predict (sorry, "project") future cycles is equally pointless
Oh Mann oh Mann
@ianl8888, a dripping tap is chaotic nonlinear. You can still predict the number of drips per hour, just not always precisely when the next drip is coming. (Yes this is an actual example from the literature).
Weather is chaotic nonlinear, but that doesn't mean climate is. Possibly the MDO is chaotic. Possibly the solar cycle is chaotic nonlinear, if so and if that drives climate so will climate be.
Is the Royal Society losing faith in the CO2 consensus?
Next week there is a meeting in Bern, Switzerland, on climate change in the holocene. I suspect their program will be broader an perhaps less biased. There are interesting contributions like this one: http://tinyurl.com/6z6xpzw studying monasteries at high altitude in the Caucasus, where cattle was kept at altitudes that are far too high for today's climate.
... In the 10th Century
However, note the fashionable newspeak for the MWP: MCA, medieval climate anomaly
From the Ecclesiastical Uncle, an old retired bureaucrat in a field only remotely related to climate, with minimal qualifications and only half a mind.
This seems to have the same objective as Sir John’s recent report.
(1) Bishop, if you had been talking of the impending arrival of Sir J’s report, would you have expected it to be ‘interesting’ like you do this one? Why not the ‘baloney’ you reported Sir J actually gave us? Was Sir J’s report unexpectedly bad? Why should this conference be ‘interesting’?
(2) Presumably the conference has been gestating for some time and they must have known that Sir J’s report was being worked on. Did they become nervous about what Sir J’s cohorts would get up to? (Any comments from a Roy Soc representative on Sir J’s blog?) Or did they just decide to have the conference to help the Gov’t through the difficulties they thought inevitable?
See: royalsociety.org/WorkArea/DownloadAsset.aspx?id=5591
If they are going to spout this sort of rubbish, heaven help us.
I believe Paul Nurse, the Royal Society, and the BBC are also working on a defense of the phlogisticated air theory of combustion (also subject to some misguided skeptical commentary). Simon Singh, Brian Cox, and Neil Wallis have been enlisted to help Sir Paul with the communications.
@Ecclesiastical Uncle
The opening sentence of the RS announcement of the seminar is interesting, that's why. We've had years of climate scientists and others claiming that the present (well, earlier this century) warming is/was unprecedented. Here, they appear to be saying that it isn't/wasn't.
Well, think of the previous interglacial, c. 117-127,000 BP. The official view is that it was just a teeny bit warmer than the present (1 degree centigrade is frequently mentioned, Hansen even talks of "tenths of a degree"
How many of you think that a 1 degree rise in temperature would have the following effects:
Hippopotami in Yorkshire
Water Buffaloes on the Rhine
Monkeys in Bavaria
Roman harbours 100's of meters away from current shoreline in England,
Large trees growing underneath 10's of m of ice in Switzerland,
Stalactites growing under sea level in Mallorca,
. . .
Sorry my last point is pointless (i shouldn't say but its Saturday night and there are a few very nice Chateneuf du Pape around here).
The stalactites thing does not fit there
EU
Not sure what your point is. Sir John's report would certainly have been interesting at the same point. It was indeed surprisingly bad - the failure to include uncertainties was shocking. I can't see why you think the meeting has the same objectives though.
From the Ecclesiastical Uncle, an old retired bureaucrat in a field only remotely related to climate, with minimal qualifications and only half a mind.
Messenger Good point. Yes, interesting if they don't forget the first sentence of the Bishop's quote in the nitty-gritty of debate, as I suspect they will.
Bishop. So I've looked again at what you wrote in your introductory peice. My point was the contrast between your expectation of the conference, which IMHO is unduly positive, and Sir J's report. I am now pleased to see your answer to the third question of my (1), which, as you will gather, entirely corresponds, to my fears for the conference. And it still looks like the same agenda to me apart from Messenger's caveat.
Sorry to waste everybody's time.
Are the causes of the MWP discussed in The Hockey Stick Illusion , anyone? I've been trying to find a discussion of it but with no luck. Have found an interesting paper Goosse et al 2006 though
Patagon
Sorry my last point is pointless (i shouldn't say but its Saturday night and there are a few very nice Chateneuf du Pape around here).
The stalactites thing does not fit there
I can recommend several cheaper and better reds than Chateau neuf du Pape. That is cher even in France.
Are the causes of the MWP discussed in The Hockey Stick Illusion , anyone? I've been trying to find a discussion of it but with no luck. Have found an interesting paper Goosse et al 2006 though
Climate models that forecast nothing without adjusting the aerosol fudge factor or some other. You will need to better than that to change our current understanding of the Med Climatic optimum, MWP or whatever you wish to call it.
@ stephen richards
I take it that's a 'no' then.
Hengist
"Are the causes of the MWP discussed in The Hockey Stick Illusion?"
You could always find out by buying your own copy. Or are you too mean..?
@James P
I have my copy right here. I'm looking for the causes of the MWP from a skeptic angle. Thought HSI would be a good place to start, since the MWP is pretty much a topic throughout. Also if there's any rebuttal to Goosse et al 2006 I'd be interested to learn of it.
"causes of the MWP"
Natural/cyclical variability?
This is an opportunity for climate science to show that it can be interested in real science. In particular, the field known as "paleoclimatology" rests entirely on circular argument. Various proxies for temperature are used without a shred of scientific justification. The argument for using the proxies goes something like this: Because tree ring measurements have been used as proxies for surface temperatures for many years, their use as proxies in research today is justified. See the circle. The original use of the proxies was never justified on scientific grounds. So, to argue from the fact that they have been used in the past to the conclusion that their use today is justified is to argue from one unjustified use of tree rings to another unjustified use of tree rings.
The circularity of the justification for tree ring proxies rose up and slapped Briffa in the face. Some of the most important tree ring proxies that were used as evidence in the articles on the Hockey Stick were found to be unreliable. Briffa found that, after 1960, tree ring data diverged from temperature data. While Briffa's thermometer data showed a steady increase in temperature from 1960 to roughly 1998, his tree ring data showed a major decline. This finding was of major importance for science. It demonstrated the necessity of investigating the behavior of tree rings in the environments that Briffa studied. Turning his back on this opportunity to contribute to science, Briffa and The Team decided to "hide the decline" by replacing tree ring data with temperature readings after 1960. Of course, the phrase "hide the decline" is actually inappropriate because what was hidden was "the divergence" between tree ring data and thermometer data. To this day, neither Briffa nor other members of The Team have done the research in the environment that would give us an understanding of how the relevant kind of tree behaves over periods of centuries in the kind of environments that Briffa studied.
What would this research produce? It would produce a set of physical hypotheses that describe how the trees respond to changes in relevant environmental variables. Obviously, temperature, ground water levels, and sunlight must be studied. Of course, scientists working in this area will identify additional environmental variables. Part of this work must be done through passive experiment, observation of existing trees, and part of this work must be done through active experiment in laboratory conditions created in nature. After this work produces reasonably well-confirmed physical hypotheses then they can be used to critically analyze the history of tree ring data. No doubt trees will be found to behave differently in different environments and historical tree ring data will have been taken from many different environments. A critical reading of the historical data will show that parts of it are useful for some comparisons across centuries and some are not.
After this scientific work is completed, there might be a scientific justification for using tree ring data as proxy for temperature data in some environments over some periods of time. This scientific justification will show that, for example, tree rings of a particular variety of tree in a particular environment over a specified period of time varied in size proportionately to changes in temperature but not changes in other variables, such as water. Until this kind of research is completed, tree ring data are useless as proxies for temperature. And articles that use tree ring data as evidence, such as the Hockey Stick articles, rest entirely on circular reasoning.
"circular reasoning"
Well, they are tree rings!
I'll get my coat...