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How Much Have Adjustments Contributed To Global Warming?

February 7, 2015

By Paul Homewood  




There has been some discussion about James Delingpole’s reference to a graph from Dave Burton.


To recap – the usual defence, when temperature adjustments are criticised, is to claim that they make little difference in overall terms. This was repeated in the Cowton video.


Dave Burton has taken the Cowton graph from the video, and added the narrative in green as above. Using specialised digital analysis techniques, Dave has calculated that adjustments have increased temperature trends for global land surfaces from 0.7527C/C to 1.01551C. In other words, about a quarter of the claimed global warming since 1900 is actually an artifact of adjustments.

I would stress that this only applies to land, and not oceans. I also make no comment about the accuracy or otherwise of either Dave’s calculations or Kevin Cowton’s graph.

Nevertheless, it does seem to throw overboard the notion that these adjustments, whether right or wrong, are too small to worry about.


There has been a suggestion that this graph is not the global one, but only applies to Paraguay. There has indeed been a fierce debate over at SkS about this, and Dave has made it clear that this is definitely what Cowton claims to be global.

The Paraguay red herring can, in any event, be easily disproven. There is only one station that goes anywhere back to 1900, and that is Asuncion. Below is the raw data plot from GISS. As can be seen, this looks nothing like the “unadjusted” curve on the Cowton graph.





I have also checked out Cowton’s YouTube video, and he clearly introduces this particular graph as global. (He even stresses that it does not include oceans).


For anyone who is interested, Dave Burton explains his methodology here.

  1. February 7, 2015 5:47 pm

    Was the rise of radical Islamism in the world simply a reaction to the rise of lock-step consensus science and the merger of church and state in the west?

    I do not pretend to know the answer.

    • Roger Cole permalink
      February 7, 2015 9:19 pm

      Any merger of church and state does not present itself to me, more like the decline and loss of self confidence of the Church and the emergence of the state as the father figure so many of us seem to need (include me out!) particularly in Europe, which is also seemingly intent on committing cultural suicide with its open door policy to Islamic immigrants. Islam has always gone through cycles of advance and withdrawal. It advances when it sees opportunity and retreats when it is strongly opposed. The present advance seems to stem from the formation of the Muslim Brotherhood in 1928 from which most of the other terrorist organisations have emerged with the notable exception of Iran, the chief state sponsor of terrorism throughout the world and a genuine threat to the West, with its nihilistic belief in the return of the Mahdi and the inter continental ballistic missiles it is building, strange for a state which professes to have no interest in nuclear weapons. It suffered a severe setback with the defeat of its Nazi allies in WW2, but emerged again to oppose the formation of Israel and its main ally the United States, which was also involved on the Arabian Peninsular in its quest for oil, a great blasphemy in the eyes of the M.B. The success of its offshoot Al Qaeda stimulated more success with the bombings of U.S. embassies in Africa, the WTC. in ’93, USS Cole and 9/11 among the most notable of its successes. With Islam, nothing succeeds like success, when it is finally correctly labelled as the vile ideology of conquest and subjugation that it is and vigorously opposed everywhere it raises its ugly head in the world, then it will retreat once again, until then we will continue to suffer losses, sometimes very great losses at its hands. It will never cease being a threat until then and wishful thinking on the part of our leaders will only concede more power and successes to it. Just my opinion and I do not discriminate between “radical” and other types of Islam, there is only one Qur’an that dictates their behaviour and beliefs to them all and therefore they are all just different wavelengths of the same spectrum.

      • February 8, 2015 3:52 am

        This is nonsense. The author has obviously never lived and worked in a Muslim-majority country.

        The author does not know that the typical Muslim in Indonesia (over 200 million of them) is not more fanatical than a Methodist, Baptist or Presbyterian. (I write as neither a Christian nor a Muslim.)

        The author does not even know that Muslims worldwide suffer more from Islamic extremists than do non-Muslims.

  2. b dussan permalink
    February 7, 2015 5:58 pm

    Just wandering when did satellite temperature measurements begin? Early 80’s?
    If so, the top graph appears to be sort of dealing with apples and oranges.

    • February 7, 2015 6:19 pm

      1979. The top graph is GHCN, not either USH or RSS (the two satellite records). RSS provides a land only mask at their website for comparison.

    • February 7, 2015 6:30 pm


      But these are surface data plots, not satellite

  3. Stocky permalink
    February 7, 2015 8:04 pm

    Surely the rate of increase is much less, because you have to adjust for UHI. The population has increased from 1billion in 1900 to 7billion now. Most of the thermometers are in built up locations / airports and the size of the adjustments for UHI are comically small.

  4. February 7, 2015 8:11 pm

    I’ve done my own calculation here. The effect on the normally quoted global average is small; a bit less than 0.05°C/Cen since 1900, and actually less for shorter periods. If you convert that to land only, it would be about 0.17°C/Cen. But it is the global index that is normally quoted, and to say that AGW is a creature of adjustments is just nonsense.

    But there is an interesting side story. A trend from 1970 to present, or any later period, is actually lowered by GHCN adjustment. And these are the trends associated with AGW that we talk endlessly about.

    I’ll write a post soon giving a breakdown by continent, rural/urban etc (Yes, S America has the biggest adjustments). But it seems the lowering of recent trends by adjustment relates to upward adjustment of airport data around 1980, relative to present.

    • February 7, 2015 10:04 pm

      What is much more significant is the trend from the 1940’s

      • February 8, 2015 4:03 am

        Not so because until 1955 CO2 cannot have had much effect. And temperatures during much of the period between 1955 and 1975 led to the global-cooling scare.

        Your work on revealing blunders in data adjustment is worthwhile mainly because it reveals the sloppy methods of the meteorological work and their unscientific approach to data collection, management and interpretation.

        Even non-scientists can appreciate that data is fundamental to scientific inquiry.

        If the scientists involved in climatology are so cavalier with the data, what other defects are present in the work? And how much of their work is biased by participation in advocacy?

    • February 7, 2015 10:06 pm

      What is much more significant is the trend since the 1940’s

  5. February 7, 2015 11:21 pm

    “The fiddling with temperature data is the biggest science scandal ever”

    By Christopher Booker10:15PM GMT 07 Feb 2015 – Torygraph

  6. February 8, 2015 5:41 am

    Thanks for posting this, Paul. The conversation about it is going on here:

    Note: if anyone here decides to jump in over there, be sure to be very, very polite, if you don’t want to be censored.

    Nick Stokes, you must be using different data than Dr. Cowtan used.

  7. February 8, 2015 5:48 am

    One quibble… I didn’t use any “specialised digital analysis techniques.” I just digitized key points on one of Dr. Cowtan’s graphs, in which he has two plots: unadjusted globally averaged temperatures, and globally averaged with NOAA’s “homogenization” adjustments.

    A wonderful free tool called WebPlotDigitizer makes this sort of thing simple (even if tedious).

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