April 05, 2010

What global warming is that?

How much global warming is there?

Amazingly, we don't know. What we do know (for the UEA's Prof Jones told us) is that over the past decade there has been no statistically significant rise in temperature – which certainly wasn't foretold.

As Ross McKitrick explains (in a contribution Bishop Hill rightly describes as astonishing, because of the lengths the establishment went to to suppress his findings), climate data is supposed to be a measure of something that does not, in most places, even exist. In most (inhabited) places around the world, the temperature outside would only be the climate if you happen to live where no one has never changed the surroundings, through any modification of the landscape.

Often the temperature data series are collected in places that have gradually got built up over time (urbanization). Producing a long time series of climate data requires making a lot of assumptions about how the various dribs and drabs of temperature data around the world need to be adjusted to reveal the continuous residual “climate signal”. In other words, all the changes in the recorded temperatures that are caused by things other than climate change need to be filtered out of the data: urbanization, deforestation, equipment modification, etc. These are called “inhomogeneities.”

That would be fine, says McKitrick, if the climate signal were large and the “inhomogeneities” were small. But it is the other way round: “we are looking for changes measured in tenths or hundredths of a degree per decade, using data from weather stations where the inhomogeneities can easily shift the record by several degrees.” So the adjustment rules matter. Whenever we see a climate data series, such as the so-called “global temperature”, what we are seeing is the output of a model, not a reading from a scientific instrument. Thermometers produce some of the basic input data, but the models take over from there.

So filtering out these inhomogeneities is critical to establishing the residual amount of any global warming. The IPCC said that “urban heat island [UHI] effects are real but local, and have a negligible influence (less than 0.006°C per decade over land and zero over the oceans) on these values.” Yet the IPCC quotes no evidence for this suggestion that urbanization has a negligible influence.

But McKitrick jointly authored a paper showing statistically that the Climatic Research Unit hadn't fully adjusted for the warming effect of urbanization. Thus the CRU surface temperature data was compromised by non-climatic biases and these “contamination effects” added up to an overstatement of warming.

Their figure certainly feels too low. When we drive out of our neighbouring town to our more rural environment, we often notice a temperature drop of 1°F. Anthony Watts has now produced a kit which anyone with their own transport can use to measure their local UHI effect. Watts has done two trial runs at his local small town and come up with an initial UHI figure of 1.5°C. This of course is way above the unsubstantiated numbers of conventional climate science, and would skittle their estimates of residual global warming.

So work on actually quantifying these 'inhomogeneities' is crucial. Yet it doesn't seem to have been done properly. One study attempted it. But two further papers showed that the UHI effects had been underestimated.

So here we are. No reliable “global warming” record, yet billions of pound of our money being thrown at a problem which may very well not exist. Scientific consensus? No. Political choice? No. Do we get to have a say at all?


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