Is there a meaningful definition of global temperature?

Question

I'm interested in your answer to this question, but I would especially like to know if you have read the paper "Does a Global Temperature Exist?" and, if you have what you think about it.

I would especially like to hear detailed technical (involving thermodynamics and so on) arguments either in support of it or in rebuttal.

Citation: (Authors: Christopher Essex, Ross McKitrick and Bjarne Andresen), Journal of Non-Equilibrium Thermodynamics; Volume: 32 | Issue: 1;
Cover date: February 2007

Link/URL: http://schwinger.harvard.edu/~motl/global-temperature-not-exist.pdf

Answer 1

The link does work, and I agree it raises an intersting point: is the "global" arithmetic average of a finite number of annual average temperatures taken at different geographic locations, a physically meaningful statistic?

The answer, as always, is that it depends. Mostly, the answer is 'no', you can't use this global average to represent anything that you could use to plan a vacation around, figure out radiation exchange numbers, etc. However, as a metric to compare aggregate behavior, the answer is 'yes'.

Really, such an average number is useful only to understand long term trends in the macroclimate. Thus, there is a relatively large amount of noise (the noise is perhaps at the 100,000 ppm level) in this number year over year, so stating an average out to 4 decimal places is a bit silly. However, it is metric by which we can compare long term, aggregate behavior of the troposphere.

What the authors of the paper are arguing is that it is pretty dumb to report an information dense temperature field as a single, lumped-together statistic. This is absolutely a good point to make, in that no one can use this statistic to make a model, or adjust a model so that they get the "right" global average in any one year.

But, as a "score keeper" number, it is useful, but with a grain of salt. The trouble is, if you want a better way to "keep score", how do you do so? It's not a trivial task. So, for now, this relatively meaningless scorekeeper number is all we have to make statements about hte long run of the troposphere.

Answer 2

I agree with the statement, and the paper supports it well. The danger is that a 'global temperature' improperly defined and calculated will be used to justify drastic measures not justified by fact and harmful to society. Worse, those calculating the temperature can manipulate its definition to suit their own objectives, like securing funding or accelerating world government.

What science needs to do is honestly and openly gather all the evidence and study it objectively. Then, resist drawing conclusions based on computer simulations based on guesses of how things might proceed in the future. So far, I have not seen that work published. The recent report by international politicians does not qualify. And especially everything Al Gore has said and written does not qualify. Let science do its work before inflicting the damage of political action. Governments are not known for doing things well. Don't get them involved without a real need.

Answer 3

Interesting...what would be even more interesting would be how many people would read or even scan past page 1, assuming, of course, that they bother to connect to the url.

BTW, I agree in practice , but disagree in theory.

Answer 4

Your link does not work.