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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Search for ns-akasofu

Comments matching the search ns-akasofu:

CO2 is not the only driver of climate

Tom Curtis at 08:46 AM on 28 May, 2016

billev @43:

"I also am of the opinion that once the current EL Nino ends then the pause will reassert itself and continue until about 2032. I base that opinion upon the pattern of previous temperature change since 1880."

Crucially for Billev, it is an untested opinion. It is only be not testing his opinion against data that he is able to retain it.

In fact, several people have already made proposals of a similar nature to Billev's claim that the pattern of temperature will repeat themselves. Specifically, Don Easterbrook has argued for a near repetition of the pattern; Akasofu has argued more abstractly that the temperature pattern is a gradually rising trend modulated by a sine function and short term variations; and Loehle and Scafetta have argued for a repeating, rising temperature pattern accelerated since 1970 by global warming. As the linked articles show, none of these projections of temperature based on a cyclical pattern have been successful.

Billev's own theory is indistinct. He clearly rejects any forcing effect from CO2, and so cannot accept Loehle and Scafetta's projection. He thinks the "cooling pattern" that he expects to repeat from 2000 onwards was evidenced in the "early 1940s" which does not align with the repetition from 1945 used by Easterbrook. It is possible that he accepts a view similar to Akasofu's, but he is not explicit enough to be sure. Regardless, neither a repetition of the 5 year running mean from 1940 (to match the early 1940s projection) or the Akasofu cyclical function matches the post 2000 temperature function:

Billev's theory is a bust - something he does not know because he never quantified it and checked it against the data. That is, he used feels to develop his theory, not reasoning, and certainly not scientific method.

As Billev seems to have dropped discussion of the role of CO2 as a climate forcing, his remaining thesis is not on topic in this thread. I would highly recommend that if he wants to defend his busted theory, discussion be moved to the theory that he thinks most closely resembles his (from the three links above), or failing that, to the general discussion of different projections here.

2011 Sea Ice Minimum

Dikran Marsupial at 23:44 PM on 30 September, 2011

I thought today would be a good day to make a statistical prediction of September 2011 sea ice extent ;o)

I obtained from data for Arctic sea ice extent from 1979-2009 (the NSIDC data archive appears to be down at the moment, that was the best I could find). I then fitted a Gaussian process model, using the excellent MATLAB Gaussian Processes for Machine Learning toolbox (the book is jolly good as well). I experimented with some basic covariance functions, and chose the squared exponential, as that gave the lowest negative log marginal likelihood (NLML). The hyper-parameters were tuned by minimising the NLML in the usual way.

Here is a pretty picture:

Note the credible interval gets wider the further you extrapolate from the data, which is a nice feature of Bayesian models. Other highlights include:

prediction for 2010 = 4.927226 (+/- 1.069078)
prediction for 2011 = 4.772309 (+/- 1.096537)
prediction for 2012 = 4.614637 (+/- 1.128915)

ice free summer unlikely prior to 2027
ice free summer probably after 2041

I haven't checked to see how accurate the first two "predictions" actually are. This isn't really a serious attempt at a prediction, I just wanted to try out the regression tools in the GPML toolbox, but when I can get some up-to-date data, I can update the projections for 2012 and onwards. Hopefully I won't end up being the subject of a lessons from predictions post. ;o)

Caveat lector: This is a purely statistical prediction, so it is less reliable than physics, but hopefully better than chimps & buckets.

2010 - 2011: Earth's most extreme weather since 1816?

Albatross at 05:08 AM on 8 July, 2011

Re "This is precisely as pointed out previously when the maximum gradient between warm and cold air occurs."

No, not always. You and others, once again, insist on making sweeping and gross generalizations when severe thunderstorms are very much about the details.

And Re #299,

This is such a site, pity you fail to recognize that. But as you volunteered on another thread, you are not particularly interested in the importance of physics. So I find your hyperbole and innuendo uncalled for, it only goes to show the weakness of your alleged 'arguments'.

Lessons from Past Climate Predictions: Syun-Ichi Akasofu

Bern at 11:00 AM on 7 July, 2011

Icarus: Very good point.

I liken this sort of 'LIA Recovery = linear upward trend' argument, to a man standing on the beach at mid-tide, screaming in panic because the water is rising and soon the entire world will be flooded...

Although I'm sure there will be plenty of deniers who would twist that around the other way when talking about climate science, the obvious point is that a model based on curve-fitting a short period of data can give you very bad results, while a model based on an understanding of the physical mechanisms that drive the tide will tell you to walk five paces up the beach and relax.

The difference now, of course, is that the curve-fitters are the ones telling us to relax, while the folks looking at the physical mechanisms driving climate have got seriously worried looks on their faces...

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