11 thoughts on “How many times does a truth have to be told ? – UHI warming has been cemented into global temperature series by adjusting for steps outward from cities”

1. “Leave the steps in – in the absence of all the hard work to adjust out UHI warming – this will produce a trend closest to reality.”

   Quite. It is shown in the paper, multiple times. Several graphs show “reference” temperatures from undisturbed sites. These trends are flat, and so are those from the target series if you just leave the steps in.

   It is really no surprise that the “trend without adjustment” is closer to the truth than the trend with adjustment. The steps only exist because the station is being moved, and the station is only being moved because of spurious warming from local heat. Each move takes the equipment to a less contaminated site, which then, with increasing urbanisation, starts showing spurious warming again, leading to another move.

   With a long record, and multiple moves, the simple solution is to leave the steps in. But what do Hansen, Jones and co. do? Take the steps out and then argue the toss about how much urban warming is left in the adjusted record. Your taxes at work…

2. Dear David Brewer, you understood the problem very well. Only your last paragraph is wrong, the homogenization method used in this article was designed to only remove the jumps due to relocations and to leave the non-climatic changes due to urbanization in the data, so that the effect of urbanization could be studied more accurately.

   The method used in this study is not used in the large global databases. For details, please have a look at my blog.

3. Warwick

   Are you still arguing that global warming isn’t occurring?

   George

4. George Bailley, there is evidence that warming has occurred since the Little Ice Age at least for the northern hemisphere. The evidence for “average” temperature changes in the southern hemisphere since the Little Ice Age is not substantial. There is some evidence that for Australia there has been no change since the first settlement by Europeans (who had some instruments) in 1788.
   However, since 1998 there has been no so-called global warming and the ice sheet extent in Antarctica (since measurements began) is at a record high.
   Whatever, the cause of northern hemisphere atmospheric temperature changes since the Little Ice Age or around 1800 (the harsh winter of 1795) it has nothing to do with human emission of CO2 particularly in Australia.

5. It has to be obvious that global temperatures have been rebounding since The Little Ice Age – 17th Century. On top of this there has been a succession of high sunspot cycles in the last 100 years but now we are suddenly in a cycle with reduced sunspot activity. Increasing CO2 could have contributed something to global trends and as you know global temperatures have paused in their rise for over a decade now.
   It is a shame that IPCC compliant scientists felt compelled to use virtually every city on the planet to compile their global trends. Apart from Dr F.B. Wood in 1988
   www.warwickhughes.com/cru86/wood.htm
   they have rarely had to reply to criticism.
   So it has been particularly enoyable for sceptics to witness the Climategate and other debacles which have rolled on for years – damaging the regard that taxpayers hold for the IPCC side of climate science.

6. “It has to be obvious that global temperatures have been rebounding since The Little Ice Age – 17th Century”. Oh good – I’m glad we all agree it is warming.

   However you (and CAF) appear to have issues with Cowton and Way’s 2013 analysis. What explicitly is wrong with this methodology?

7. George Bailey

   In relation to Cowtan and Way 2013, I suggest you read through the CA post on this. Robert Way comments at length to various critiques and both essentially and explicitly says that infilling the sparseness of actual observation points in the Arctic is statistically fraught

8. Ian,

   I’m not quite sure of the point you are trying to make, but there is general agreement among scientists and the less rabid denialists that Cownton and Way (2013) have produced an analysis that is both defendable and robust. I’m sure in every scientific endeavour improvements can always be found, but Cownton and Way (2013) has stood up very well under scrutiny, and is very likely to be our best estimate of global temperatures to date. As such any commentary that any “pause” is underway is ill founded. Most particularly, when El Nino / Neutral / La Nina forcings are taken into account the temperature anomaly upwards trajectory continues unabated. Rhetoric is easy, science is hard (but inevitably worthwhile).

   George

9. Apologies CF, Ian, Warwick.

   This sorta hits your arguments outa the park .. “The net result is to cast serious doubt on the much-discussed “pause” in global surface temperature.” .. tamino.wordpress.com/2014/02/06/cowtan-way/

   Kind regards

   George

10. There could be another contributing factor to the step apart from UHI. This would also get cemented in. If the site is scheduled to be moved and near the end of its life maintenance is minimised. What is the point of painting it if it will move next August? etc.
    So sun affected old boxes with peeling and cracks may show an up slope that is not soley due to UHI.

11. Lance I agree absolutely that very local site and instrument hardware changes often seem to affect station data either at the start or end of a time series – This could be due to staff losing interest in the old site as the new one overlaps – as you say maybe issues of maintaining the box. Who knows. At the start of a time series it is easy to understand the brand new conditions could affect data until routine admin etc sets in.
    Years ago I commented on Orange Post Office which showed a severe trend before it was closed – see link below from ~2000. There are some ripper difference trends from several USSR stations on this page too.
    www.warwickhughes.com/climate/quality.htm
    all contributed to global warming.