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How The US Temperature Record Has Changed

January 18, 2018

By Paul Homewood


The topic of how the US temperature record has been massively altered in recent years has been well covered by Tony Heller, myself and others in the past.

Nevertheless it is worth summarising again.


In 1999, James Hansen, Reto Ruedy, Jay Glascoe and Makiko Sato of GISS published a paper, “GISS analysis of surface temperature change”, which included this graph of the US temperature record at that time.





The drop in temperatures from the 1930s to the 1970s is absolutely clear.


The paper commented:


The U.S. temperature increased by about 0.8°C between the 1880s and the 1930s, but it then fell by about 0.7°C between 1930 and the 1970s and regained only about 0.3°C of this between the 1970s and the 1990s. The year 1998 was the warmest year of recent decades in the United States, but in general, U.S. temperatures have not recovered even to the level that existed in the 1930s. This contrasts with global temperatures, which have climbed far above the levels of the first half of this century.


This dichotomy with global temperatures clearly posed a problem for Hansen and co. So they wrote a brief, which attempted to explain why the US temperature trend was out of line:

What’s happening to our climate? Was the heat wave and drought in the Eastern United States in 1999 a sign of global warming?

Empirical evidence does not lend much support to the notion that climate is headed precipitately toward more extreme heat and drought. The drought of 1999 covered a smaller area than the 1988 drought, when the Mississippi almost dried up. And 1988 was a temporary inconvenience as compared with repeated droughts during the 1930s “Dust Bowl” that caused an exodus from the prairies, as chronicled in Steinbeck’s Grapes of Wrath.

How can the absence of clear climate change in the United States be reconciled with continued reports of record global temperature? Part of the “answer” is that U.S. climate has been following a different course than global climate, at least so far. Figure 1 compares the temperature history in the U.S. and the world for the past 120 years. The U.S. has warmed during the past century, but the warming hardly exceeds year-to-year variability. Indeed, in the U.S. the warmest decade was the 1930s and the warmest year was 1934. Global temperature, in contrast, had passed 1930s values by 1980 and the world has warmed at a remarkable rate over the last 25 years.



Figure 1

Fig. 1: Annual and 5-year mean surface temperature for (a) the contiguous 48 United States and (b) the globe, relative to 1951-80, based on measurements at meteorological stations.



A picture of how U.S. climate change during the past half century compared with the rest of the world is shown in Figure 2. This map shows that the trend has been toward warmer temperatures in most of the world. There has been nearly ubiquitous warming in the tropics, especially in the Eastern Pacific Ocean, where the largest warming coincides with the location of more frequent strong El Niños. The strongest warming has been in Alaska and northern Asia. Warming in Alaska is often associated with El Niños. A suspicion of many climatologists — as yet unproven — is that an increasing greenhouse effect may cause more frequent and intense El Niños. Asia has long been predicted to show the largest warming due to increasing greenhouse gases, especially in the winter, and observations are consistent with that.

Yet in the U.S. there has been little temperature change in the past 50 years, the time of rapidly increasing greenhouse gases — in fact, there was a slight cooling throughout much of the country (Figure 2). We caution that linear trends, as in Figure 2, can mask temporal detail. Indeed, Figure 1(b) indicates that the last 20 years have seen a slight warming in the U.S. Nevertheless, our analysis (Hansen et al., 1999a), summarized in Figures 1 and 2, makes clear that climate trends have been fundamentally different in the U.S. than in the world as a whole.

Is this a temporary fluke, a chaotic regional climate fluctuation? If so, as the regional fluctuation reverses and global warming continues, will the U.S. experience dramatic, perhaps “disastrous” climate change in the next few decades? Or is there an understandable and continuing reason that the U.S. is warming less than the rest of the world? In that case, will the U.S. be relatively immune to global warming in the next several decades?

In order to answer such questions and predict future climate change reliably, a prerequisite is an understanding of the cooling of the past half-century in the U.S. Figure 2 suggests that the U.S. cooling is associated, at least in part, with cooling in the North Atlantic Ocean. Climate model simulations tend to confirm this, yielding cooling in the U.S. during the past 50 years when driven by observed ocean temperatures (Hansen et al., 1999b).

But that only changes the question: what is the cause of the Atlantic cooling? In part, the Atlantic cooling is a natural fluctuation, the North Atlantic Oscillation, that occurs on decadal time scales. Observations of the past few years, summarized in Figure 17 of Hansen et al. (1999a), suggest that the North Atlantic Oscillation is now moving into its warmer phase.

However, North Atlantic cooling is also a predicted consequence of the transient growth of greenhouse gases. Climate models (Manabe and Stouffer, 1995; Russell and Rind, 1999) driven by increasing greenhouse gases yield increased precipitation at high latitudes, decreased ocean salinity in the North Atlantic, and thus a weakening of the ocean conveyor belt that transports heat to the North Atlantic.

Additional mechanisms may contribute to observed climate change. For example, in the decades after World War II, when the amount of aerosols (fine particles) in the air grew most rapidly in the Eastern U.S., the pattern of cooling showed a clear resemblance to the distribution of aerosols. Also changes of solar irradiance (the brightness of the sun) are difficult to dismiss as a mechanism of climate change, because there are observed correlations of solar variability and climate change.

The upshot is that we will be able to understand climate change well only with the help of global climate models that are able to incorporate all of these mechanisms on an equal footing. We will be able to test our understanding during the era of satellite measurements, when all of these forcing factors can be measured accurately.


But there was actually a much bigger problem for GISS. During that warm period of the 1920s to 60s, most of the world’s temperature data came from the US, along with Europe and Australia.

Most of the rest of the world had very little in the way of reliable data.



Moreover the US data was high quality stuff from USHCN. This could not be so easily dismissed as it put into doubt the claimed increase in global temperatures.


NOAA however had the answer, and adjusted the US data out of all recognition. Now it looks like this:




Take a close look at the data for 1934 and 1998.

The new chart tells us that the temperature anomalies (relative to the 1951-80 mean) were 1.19C and 1.33 respectively. In other words, 1998 was 0.14C warmer than 1934.

Yet on the original 1999 chart, 1934 was clearly a lot warmer than 1998. We don’t have figures, but eyeballing suggests that the 1934 anomaly was about 1.5C, while 1998’s was about 0.9C, that is 0.6 hotter.

Overall then, NOAA have reduced the 1934 temperature by 0.74C, relative to 1998.

The hottest year on record, according to the current version of the US temperature history, is 2012, with an anomaly of 1.86C. However, if you take off the adjustment of 0.74C, it still leaves 1934 as the warmest year.


NOAA claim that these adjustments are mainly to allow for time of observation changes (TOBS), yet their own analysis shows that these only account for around 0.5F,  about 0.3C. (Also note that NOAA’s webpage explaining all of this is no longer available, but fortunately is still obtainable on Wayback).



So NOAA’s “explanation” accounts for less than half of their changes. Yet there are no specific adjustments for the effects of UHI, which must be substantial as well.

As Ronan Connolly has shown, there are very real concerns about whether the current homogenisation methods used by USHCN adequately take account of UHI. Indeed there is a likelihood that rural stations are actually being adjusted to match urban trends.

And as Anthony Watts has also revealed, temperature trends at rural USHCN stations are lower than those at urban ones.


In summary, the adjustments to the US temperature record made by NOAA are more than double the ones they have admitted to. Furthermore they have not been making proper allowance for UHI.

The US temperature record presented by NOAA and GISS is little more than a political construct.

  1. quaesoveritas permalink
    January 18, 2018 10:31 pm

    Posting and discussing this here is all very well but it needs to be more generally known.

    • Mike Jackson permalink
      January 19, 2018 10:00 am

      Only going to happen if this entire analysis is put to the cuplrits in front of a Congressional Committee hearing and they are grilled until the pips squeak.

      In essence we have been too generous (or do I mean gentlemanly) on this whole subject for too long. There has to be a US equivalent of Misconduct in Public Office and the manipulation of these figures is so blatant and so blatantly intended to create a warming that does not exist that the best that those involved could do is plead “no contest”.

      There is 100% no evidence of any man-made global warming other than increased UHI and ditto evidence that marginally raised CO2 levels have any part to play in anything at all other than a beneficial greening of the planet.

      The bottomless pit of money which is being extracted from the pockets of taxpayers and energy consumers and is being used to fund the coffers of energy companies, governments and pseudo-scientific “research” has effectively corrupted the body politic on both sides of the Atlantic to a point where criminal charges against the perpetrators are going to be the only way out.

      If indeed we aren’t already too late since the perpetrators, or at least their political lackeys, are already starting to use the criminal courts to prevent their own criminality from being challenged. And, knowing the extent to which the US legal system can be manipulated, I cannot be optimistic about the outcome.

      • dennisambler permalink
        January 19, 2018 11:41 am

        It seems to depend on the political affiliation of the judges.

      • Mike Jackson permalink
        January 19, 2018 1:22 pm

        dennisambler —
        Precisely my point. The ability to hawk your cultish beliefs around the US until you find a sympathetic judge is, to my mind at least, the biggest stain of all on the integrity of the US.

        Much of the evidence is anecdotal of course but there is a lot of it out there!

  2. JerryC permalink
    January 18, 2018 11:34 pm

    If the data doesn’t fit the theory…adjust the data until it does.

  3. January 19, 2018 12:46 am

    From the article: “Nevertheless, our analysis (Hansen et al., 1999a), summarized in Figures 1 and 2, makes clear that climate trends have been fundamentally different in the U.S. than in the world as a whole.”

    I must say I am very surprised to see this statement in your article.

    The fact is the U.S. surface temperature profile is mirrored in unmodified temperature charts from around the globe, including the southern hemisphere.

    All these unmodified charts resemble Hansen’s 1999 chart with the 1930’s showing to be as hot or hotter than subsequent years. These unmodified charts from around the world look nothing like the bogus, bastardized Hockey Stick charts. The Hockey Sticks are a fraud whether they cover the U.S. or the world.

    You have shown these unmodified charts on this very website so how can you make this claim?

    To say the U.S. and the rest of the world are very different when it comes to temperature is ridiculous.

    • Athelstan permalink
      January 19, 2018 12:55 am

      Put that in English.

    • January 19, 2018 10:18 am

      It’s not my claim, but what Hansen wrote!

  4. jim permalink
    January 19, 2018 3:01 am

    Paul, for goodness sake stop falling into the trap of quoting anomalous anomalies.
    Just talk about real temperatures!!!
    We are lost, completely lost if we fall for the warmist trap of using anomalies.
    Anomalies are rubbish, they are a figment of imagination.

    • dave permalink
      January 19, 2018 10:33 am



      (1) everybody (mentally) substituted ” difference from average for 1981-2010 [or whatever] ” for ” anomaly, ” and,

      (2) the established ” average ” were never sneakily changed, and,

      (3) all unscientific, negative, connotations were ignored, then,

      “anomaly” would not be a problem word.

      Almost all the words in ” climate ‘science’ ” are ” faux amis. “

    • dennisambler permalink
      January 19, 2018 12:35 pm

      Agree and the public generally think that they are being told actual temperatures. This explanation on the GISS website was originally under the imprimature of Hansen, now Gavin Schmidt. A must read FAQ.

      It is clear from the information here that it is impossible to legitimately measure Surface Air Temperature, SAT, however:

      “Q. If SATs cannot be measured, how are SAT maps created?
      A. This can only be done with the help of computer models, the same models that are used to create the daily weather forecasts. We may start out the model with the few observed data that are available and fill in the rest with guesses (also called extrapolations) and then let the model run long enough so that the initial guesses no longer matter, but not too long in order to avoid that the inaccuracies of the model become relevant. This may be done starting from conditions from many years, so that the average (called a ‘climatology’) hopefully represents a typical map for the particular month or day of the year.

      Q. What do I do if I need absolute SATs, not anomalies?
      A. In 99.9% of the cases you’ll find that anomalies are exactly what you need, not absolute temperatures. In the remaining cases, you have to pick one of the available climatologies and add the anomalies (with respect to the proper base period) to it. For the global mean, the most trusted models produce a value of roughly 14°C, i.e. 57.2°F, but it may easily be anywhere between 56 and 58°F and regionally, let alone locally, the situation is even worse.”

      Amazing how every year is the warmest on record

      According to NOAA’s 1997 state of the climate report:-
      “The global average temperature of 62.45 degrees Fahrenheit for 1997 was the warmest year on record, surpassing the previous record set in 1995 by 0.15 degrees Fahrenheit.”

      62.45 F = 16.92 C

      According to NOAA’s 2014 state of the climate report:-

      “The year 2014 was the warmest year across global land and ocean surfaces since records began in 1880. The annually-averaged temperature was 0.69°C (1.24°F) above the 20th century average of 13.9°C (57.0°F), easily breaking the previous records of 2005 and 2010 by 0.04°C (0.07°F).”

      (I love “easily breaking records” by 0.04 C, such precision).

      This says quite clearly, that 2014 global temperature was 13.9 C plus 0.69 C. I am not brilliant at maths but I make that 14.59C, or 2.33 C colder than 1997, yet it was still the warmest on record!

      (The GISS page says global temperature may be as high as 58 F, or 14 .44 C, but the most trusted models give 14 C, roughly.)

      How did that 2014 reduction happen with increasing CO2? And here we are trying to stop the globe warming by that same amount by cutting down on oil and coal use, we already did it!

      The whole thing of course is nonsense, but it is presented as an appeal to authority, (how do you, an ignorant peasant, know more than these government scientists?)

      David Parker wrote in 2005, [Climategate e-mails]:

      “There is a preference in the atmospheric observations chapter of IPCC AR4 to stay with the 1961-1990 normals.

      This is partly because a change of normals confuses users, e.g. anomalies will seem less positive than before if we change to newer normals, so the impression of global warming will be muted.”


      Phil Jones response was as follows:

      “Just to reiterate David’s points, I’m hoping that IPCC will stick with 1961-90. The issue of confusing users/media with new anomalies from a different base period is the key one in my mind. Arguments about the 1990s being better observed than the 1960s don’t hold too much water with me.

      There is some discussion of going to 1981-2000 to help the modelling chapters. If we do this it will be a bit of a bodge as it will be hard to do things properly for the surface temp and precip as we’d lose loads of stations with long records that would then have incomplete normals.

      If we do we will likely achieve it by re-zeroing series and maps in an ad hoc way.”

      The thirty year average Central England Temperature Record for 1931-1960 was 9.60 deg C and yet the “baseline period” 1961-1990 was colder at 9.47 deg C. Why should we accept 1961-90 as “normal”?

      Comparisons, (anomalies) against a cold normal are guaranteed to produce “warming.” As David Parker implied so clearly, you need to choose the right normals to support the narrative.

      • A C Osborn permalink
        January 19, 2018 3:37 pm

        Dennis, I have been showing the 1997/98 data whenever I can.
        But the warmist answer is “The Baseline changed”.
        No amount of argument can change their minds that there is absolutely nothing wrong with dropping the 1997/8 data by a couple of degrees.
        Which is why NASA/NOAA put the comment on their site in the first place.

    • Gerry, England permalink
      January 19, 2018 1:59 pm

      Graphs showing the estimated global temperature – estimated since it can’t be derived from global stations everywhere as they don’t exist – would if scaled to zero show no change. Zooming the axis in would show nothing scary either. So hence the anomaly. But the huge cherry pick is what you make it anomalous to. The simple answer is to make it anomalous to that time when the earth was at the stable ideal temperature which was er……er….

  5. Dave Vought permalink
    January 19, 2018 3:14 am

    All of the remodelling around the worlds past temperatures are all made up lies for the big global warming BS sell.
    Any scientists who bases anything on the models And not the past true records is a lazy fraud.
    They have placed their whole career and reputation on make believe re done temperatures.

  6. January 19, 2018 6:32 am

    Based on this and other fake data, the UN tells us that 2017 was the hottest year on record (taking account of El Nino).
    The climate change scam continues regardless of the facts.

  7. Paddy permalink
    January 19, 2018 7:37 am

    The recent tendency of the UK Met Office forecasts to quote urban temperatures, and then to add that rural temperatures will be a degree or so lower than this is also questionable.

    • Ben Vorlich permalink
      January 19, 2018 9:18 am

      In what way questionable? If you mean that that one or two degrees isn’t enough of a difference then I agree (although for 80% of the UK population it will be true). However getting the MO and the BBC to regularly tacitly admit that there is a large UHI effect is a major step forward.

    • Gerry, England permalink
      January 19, 2018 2:02 pm

      As I have said on here before, I have measured difference of 5C – yes FIVE – between the south London suburbs and my home in the country in Surrey. And something that surprised me was during a cold spell to measure the same difference of 5C between the edge of Gatwick airport in the commercial estates around the perimeter and my home.

  8. Malcolm Bell permalink
    January 19, 2018 8:54 am

    Whilst suggesting that the US data is now adjusted to being “fake news” do you agree with the rest if world that we are in general warming?

    Do you agree with the BBC statement as I was falling asleep last night that 2017 was the warmest ever?

    If the Atlantic is cooling the US – is it also cooling the UK and N. France?

    • Ben Vorlich permalink
      January 19, 2018 9:24 am

      My Answers to your questions are

      Yes, by an unidentified process and it is generally a good thing

      Possibly with the caveat temperatures have only been measured accurately for 150 years across some of the world, when you measure in anomalies and change the baseline then it is impossible to know anything for certain. Generally it is a good thing

      Not necessarily, ocean currents are complex.

      • Malcolm Bell permalink
        January 19, 2018 12:14 pm

        Ben, yes I suspect that at least imcreasing CO2 is good and maybe a few degrees of warming may be good. Both could help with greening. (They may increase rain fall in arid areas too – but that is just wishful thinking).

        As for modelling – I have done a lot of that in my Engineering career and it stands or falls on one thing – comparing the data output with the actual results, closing the loop. We call that science. Which climate speculator (most are not scientists as Newton would recognise them, just academics) actually closes the loop to make the model fit the facts – not the facts fit the model?

    • Gerry, England permalink
      January 19, 2018 2:07 pm

      No – the modern warm period has ended and any warming that we are currently seeing is due the El Nino Southern Oscillation releasing heat. ENSO is not something that is understood and so stands out as yet another anomaly to the ‘settled science’ as it can’t be modelled. We sit on the cusp of a period of sustained cooling that could be deep or very deep.

      No – the BBC and the MetO are not a reliable source of information.

  9. January 19, 2018 9:57 am

    ‘the pattern of cooling showed a clear resemblance to the distribution of aerosols.’

    Sorry, but correlation is not necessarily causation. As soon as there’s any sign of warming they conveniently forget about aerosols.

  10. Europeanonion permalink
    January 19, 2018 10:08 am

    Until Paul can become an authority (like Roger Harribin, oh dear) then for all this spectacular commentary and earnestness this site will only be of interest to a quasi-Druidic cultists and the habitat of others awaiting the second coming. Expose is needed rather than expostulation.

    • Gerry, England permalink
      January 19, 2018 2:08 pm

      What is needed and what is on its way is a sustained period of cooling that consigns the whole warming scam to the dustbin of human idiocy. I can’t really see anything else really killing it off.

  11. Robert Stitt permalink
    January 19, 2018 5:26 pm

    We should refuse to pay the license fee as the BBC are committing fraud. The 35pence in the pound surcharge on our electric bills we should also claim back due to the propaganda we are forced to put up with and which many succumb to.

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