How to create global warming

Climate Audit takes a look at some of the Australian weather station data that has been used by several authors to support the case for anthropogenic global warming.

He shows, rather successfully, that if you adjust the data at the start of the series - the 19th century- downwards, you can create a warming trend out of nothing! A set of data with no clear trend....

 

is magically transformed into this....

 

And if this isn't to your taste, it's possible to produce the same effect by careful choice of your start and end point.

Mind you, the authors have excellent reasons for tweaking the numbers:

For example, cows and goats have been known to mill around the instruments at country stations, and in one case an eagle destroyed a Stevenson screen by flying into the side of it. A dingo once stole a thermometer which had been read following the slaughter of farm animals (the observer was advised to wash his hands in future), and crows also like to make off with these shiny objects. An irate wife, tired of being woken every morning as her husband made the 3am observations, took to the valuable screen with an axe, turning it into a pile of firewood. 

Amazing. 

It is startling to think that we are making multi-trillion dollar decisions on the back of science of this "quality". Do you think anyone will notice?

That 800 year lag

One of the most striking claims of the Great Global Warming Swindle was that in the historic climate record,  the temperature rise preceded the rise in CO2 by approximately 800 years. On the face of it, this is pretty good evidence that temperature is driving CO2 rises rather than the other way round, which is exactly what the heretics claimed in the programme. As far as I can see, its existence is largely undisputed (although I have been pointed to one dissenter).

The orthodox response to this is that CO₂ is a feedback mechanism. Something causes CO₂ to rise. Because CO₂ is a greenhouse gas, it warms the earth, which raises CO₂ levels, which warms the earth further and so on. My initial objection to this was that the cycle should feed back exponentially. Apparently the answer to this is that the supply of CO₂ is l finite, so when it runs out the feedback loop is broken. But nobody actually knows what causes the rise in CO₂ anyway, so we're in the dark as to the details.

From my perspective, this all looks somewhat dodgy. Both methods rely on an initial warming of the earth to produce CO₂ (by a mechanism which isn't understood). The heretical case is that that's the end of the story. Warming produces CO₂. (I assume they argue that any warming from the CO2 is small because, relative to water vapour, the contribution of CO2 to the greenhouse effect is small). The orthodox case, however, imposes a CO₂ feedback on the initial process. This, however, requires another process to prevent the feedback spiralling out of control - one which is inextricably mixed up with whatever started the whole cycle off in the first place.

Which seems, I must say, a tad unconvincing. Certainly not something I'd like to rely on before I took drastic action. The orthodox case seems to fall foul of Occam's razor. 

I must say, I feel certain there must be more to it than this, so if anyone can enlighten me, I'm always keen to hear.  Why is the the heretical case not considered more plausible? What is the flaw in their case which requires imposition of a feedback loop?

As always, I should point out that I'm an interested amateur rather than a professional scientist, and there is a possibility I've got either camp's arguments (and probably both) completely wrong.

Is there such a thing as a global temperature?

This is the question asked in a paper by Essex, McKitrick and Andresen in a fascinating paper which can be found here. (Mathematics alert!). This is my understanding of it - I haven't done any maths since university days, so if I'm wrong I'm sure someone will put me right.

Some quantities, like weight, can be added and therefore averaged. If you take an 2oz mass and a 1 oz mass you can say with certainty that their total mass is 3oz. Because the sum of the two masses means something, you can calculate an avarage of 1.5oz and this figure has a useful meaning also. These kinds of measures are called extensive variables. Pressure, on the other hand, can't be treated in this way. If you add a system at 2 atmospheres to one at 1 atmosphere you don't get a system at 3 atmospheres. Because the sum of the two pressures has no meaning, the average likewise is meaningless. These are called intensive variables.

Temperature, as you might suspect, is an intensive measure. This means that when you add two temperatures together, the answer cannot be a temperature. It's meaningless. As the authors point out, dividing this meaningless sum by the number of components cannot give you an answer which has a meaning.

If the average of temperatures is not a temperature, then perhaps it's an index - a number which tracks whatever it is that drives the climate? If this is the case, then it is presumably necessary to describe how the average of temperatures - a statistic - is driven by the underlying climate driver, or at least to show some correlation between the two. They also need to demonstrate that the statistical measure they have chosen is better than any other measure they could have chosen. These alternative measures might well demonstrate a completely different trend to the average.

A third alternative is that the average is neither a temperature or an index, but a proxy for energy. But unfortunately there appear to be problems with this argument too. For a start, to do so is to use an intensive measure as a proxy for an extensive one. Secondly, the relationship between energy and climate is not understood. How then is it possible to know that the average of temperatures is a valid proxy?

It's not instantly obvious to the lay reader, but there are lots of different kinds of means. We're used to dealing with arithmetical means ("averages") but you can also have geometric means, harmonic means and any number of other means. For some systems, physics suggests which is the correct one to use. But, alas, this is not the case for global temperature.

As if to rub this point in, the paper demonstrates that there are in fact an infinite number of different means for global temperature. Which, they ask, is the correct one? Why has the scientific community alighted on the mean it has? They go on to show that, for the same set of data, different means can show a rising trend or a falling one. In other words, if a different averaging method to the one used in climate science had been chosen, we might now be having a crisis about global cooling... again.

It's a fascinating piece of work, some of which is beyond my understanding. If you are mathematically inclined, do take a look and tell me what you think.

What's going on here then?

One of the most important scientific documents in the global warming debate is Jones et al 1990 on the Urban Heat Island (UHI) effect. This was long claimed by sceptics to be a major factor in the apparent rise in global temperatures - essentially they were saying that as urbanisation took place, many formerly rural weather stations ended up surrounded by buildings. These gave off heat and raised the local temperature. In other words it looked like global warming, but wasn't.

Jones' letter to Nature in 1990 was widely claimed to have killed this argument off by presenting three temperature time series from rural weather stations.  By comparing these to another wider set of data, it was possible to show that the wider series had no significant UHI effect.

The story has suddenly come to the fore again because the UHI effect has attracted the interest of Steve McIntyre, a  prominent sceptic and something of a thorn in the side of the mainstream. He has been asking the author, Phil Jones for his raw data - specifically he wants to identify which weather stations were used his work - presumably he means to test if they were genuinely rural or not.

And thus far, Jones has refused to release the information, despite a formal request under the Environmental Information Regulations.

Now to anyone who knows anything about science, this is pretty exciting stuff. It's pretty much a given that you release your data on request so that others can test it. Nature, which published the orginal letter, makes prompt availability of data a condition of publication. So the refusal is likely to be viewed in a pretty dim light by the scientific community, or at least I hope it is.

There are other lines of enquiry for McIntyre to pursue in order to get the data, but in the meantime let's just notice the startling fact of a "real" scientist refusing to release his data to someone who is alleged to be a fake and the equivalent of a creationist.  

Volcanoes

Frank O'Dwyer tells me that the claim made in the Great Global Warming Swindle about volcanoes releasing more CO₂ into the atmosphere than humans is wrong. I've not been able to make a lot of progress in getting to the bottom of either Frank's claim, or the GGWS one, but I did come across something quite interesting.

74,000 years ago, the Toba volcano erupted in a VEI 7 explosion that pumped more than 10,000 times as much CO2 into the air as Mt. St. Helens did. At the maximum, Mt. St. Helens was giving off 22,000,000 kg of C02 daily, so Toba was putting out at least 22 billion kg per day. The ash cloud was so thick that it caused cooling that nearly wiped out the human race.

There are indications in the ice core records that show the cooling from Toba, but where is the global warming that should have resulted from all the CO2 put into the atmosphere? According to what I've read, the CO2 should have remained in the air long after the ash settled and that should have caused at least a warming spike, but there's no sign of extraordinary warming in the climate records. Shouldn't there always be a cooling/warming cycle after a volcano erupts? Cooling from the ash cloud, warming from the CO2 that lingers?

 Source