progressiveslol wrote on Feb 27^th, 2012 at 5:55pm:


Did they? Give us some examples.


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Well most people have heard the message from every serious scepical scientist but some choose to ignore it for some reason. I should add that Anthony Watt is not a serious sceptical scientist.  He's not even a scientist in fact.

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That's not the sceptics' case, and it doesn't represent the views of any "serious sceptical scientist" that I'm aware of. It contains a lot of .... untruths. The person who wrote this does not deserve the descriptor of sceptic. A more appropriate term is "blatant liar" and I'll explain why in this post. Scientist are by nature sceptics. So he needs to correct the Title. It should read "The Liars' case"

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Rarely admit?????? That's where blatant lie comes in.  How about "openly publicise?

"The Physical Science Basis" from IPCC Working Group I devotes a whole chapter to this:

Chapter 2: Changes in Atmospheric Constituents and in Radiative Forcing

He then goes on to argue that Hansen's predictions were wrong using temperatures plotted on a monthly basis (Watt's up with that!? ) when he should be using something like 15 year running averages to monitor actually changes in climate compared to predictions. It's a very fallacious argument where he's taking advantage of natural short term cycles when everybody who knows anything about climate is aware that these exist, and generally smooth out short term variations using the techniques previously described.

Now if you want the view of real sceptics, here it is:

http://www.skepticalscience.com/Hansen-1988-prediction.htm

The summary:

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Anthony Watt has no university qualifications and no climate credentials other than being a radio weather announcer. He probably has a good microphone voice, but that's about it.

From Anthony Watt's Site:

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OK, so if we use that climate sensitivity of 0.6 instead of about 3, and apply that to the graph, the orange line represents where that prediction takes us.

If these guys think Hansen's prediction was bad, then  their stated climate sensitivity produces a prediction that's 10 times worse. (fail)

You would also think that the esteemed highly qualified radio announcer would have worked out that particular chestnut by now.  Of course that would make him either breathtakingly dumb... or a liar.

Which one do you think he is?

progressiveslol wrote on Mar 2^nd, 2012 at 1:15pm:


What do you think Climate sensitivity means? It's an empirical factor that includes all forcings and feedbacks. It means change in temperature for a given rise in carbon dioxide (bearing in mind that it's a logarithmic relationship).

Of course you have to apply all other feedbacks and forcings (including those that are independent of atmospheric CO2). Those include solar irradiance, aerosols, soot, volcanic emissions etc. The attribution of these feedbacks is covered in Chapter 2. They are not ignored as you claim below (highlighted). The net effect of those has been demonstrated to be slightly negative, Forcings and feedbacks are reported in Watts per square metre. A forcing of 1.5W/m2 gives us a temperature increase of 1 degree (of course you need to apply a reference timeframe) That forcing  has the same effect whether it's coming from a change in solar irradiance or an increase in water vapour.

So you can easily take a value of climate sensitivity and calculate what the expected rise in temperature would be on top of these natural factors, given a long enough time-frame to allow for equilibrium.  That's the whole point of climate sensitivity.

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Hang on though, Dave's study quotes a climate sensitivity based on CO2. The water feedback, which is the major feedback follows the atmospheric CO2. By using the term climate sensitivity, you accept that relationship.

It's obvious that as temperature goes up, average water concentration in the atmosphere goes up too, and water vapour is a greenhouse gas which adds to the effect. However Dave is claiming a negative feedback, giving an overall climate sensitivity that doesn't come close to the actual experience of the last 50 odd years. 

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Again, you fail to understand the term climate sensitivity. It has a very specific meaning in this context.

I'll try to edit this over the next couple of days with illustrations from Dave Evans' (The self-proclaimed rocket scientist) paper. 

Dave's article says:
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Satellite data was notoriously susceptable to Dr Roy Spencer (UAH)
discarding the higher values from the dataset. The datasets used in this article are the doctored ones.  It seems an appropriate term.

More from the rocket scientist:
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OK, so a doubling of CO2 gives causes a radiative forcing of 3.7 W/m2, which in equilibrium would cause 3°C (plus or minus 1.5°C) of global warming. On the face of it, the actual results  for the industrial period are only about 1/4 of that, however they don't account for ocean heat uptake. So the temperature rise experienced does not reflect equilibrium conditions. You arrive at a climate sensitivity of around 1.5 degrees based on recent historical data. Taking into account equilibrium factors, we get to  a result of 3 degrees. (that's a more lengthy explanation) The single factor that causes most uncertainty is the cooling effect of aerosols.

There is a German paper that was written about 3 years ago. I'll try to find that some time over the next few days. It explains all the factors in some detail much better than I could. (give me a week or so) It also shows a probability graph against various climate sensitivities.

OK, the reason I couldn't find it was that I was looking for a paper. It's taken from a book, but is still peer reviewed. Here is the URL:

http://www.pik-potsdam.de/~stefan/Publications/Book_chapters/Rahmstorf_Zedillo_2...

The good thing about that spiel if that it summarises the science pretty well. As I've said before, if you want to argue against a certain position, you first need to understand what the position is, otherwise you're wasting your time. 

Well this is a very good start, so if you read things on blogs that say things like "they don't take any other factors into consideration apart from CO2" you can check the validity of such statements against this publication.

It's called a strawman - a dishonest tactic that starts with misrepresenting the position of an opponent.

Now that article from Dave Evans is actually not bad in that a lot some of the technical detail is correct. However it is wrong in specific crucial areas. The central paradigm is negative feedbacks.  He bases this on the work of Lindzen. The problem is that the overwhelming majority of studies show a climate sensitivity clustered around 3, not 0.6, and it doesn't take a lot of technical knowledge to calculate this out for yourself.