More on the record high-low temperature debacle

U.S. Record Temperatures—A Closer Look

From World Climate Report:

high-low-thermometerA new paper that is soon to appear in the journal Geophysical Research Letters finds that across the U.S. daily record high temperatures are being set at about twice the frequency of daily record low temperatures and that this ratio—number of record highs to the number of record lows, has been growing larger over the past 50 years.

The popular press seems to be particularly taken with this finding, although headline proclamations fail to disclose important details of the actual findings reported by the National Center for Atmospheric Research’s (NCAR) Gerald Meehl and colleagues.

Although you can hardly blame the press, because the NCAR press release did much to lead them down this muddy path.

Meehl et al. find that the reason more daily maximum temperature records are being set than daily minimum temperatures records is because there are fewer than expected daily lows records being set, not because there are more daily high records than expected.

In other words, our days are not becoming extremely hotter, but our nights are becoming less extremely cold. This fact is buried in the press release and consequently in most of the coverage—likely, because this finding has pretty benign, if not beneficial, implications.

Instead of highlighting this, the NCAR press release not only tries to confuse it with all sorts of graphs and numbers (presented without a proper reference frame of the expectations), but by also suggesting that this observation—nights warming more than days—is what is expected because of a rising greenhouse effect, and they have a model to prove it.

While it is true that an enhanced greenhouse effect should warm nights more than days, so too does the processes of urbanization—something which has not been accounted for in the results of Meehl et al. (because it is virtually impossible to do so at a daily level), but something that is widely known to be occurring.

A report just published earlier this week estimates that urbanization and other land use changes are responsible for half of the observed temperature rise in recent decades in the U.S. This is similar to what Ross McKitrick and WCR editor Pat Michaels found for global land-based temperatures in a paper published two years ago.

Further, despite the contention that climate models show the nights-warming-more-than-days expectation from an enhancing greenhouse effect, the model results depicted in Meehl et al.’s paper don’t show this at all. In fact, the model in the paper—the NCAR climate model—shows that it expects daily high records should be being increasing (above expectations of no climate change) at about the same frequency that daily minimum temperature records should be decreasing. This model expectation is shown by observations to be wrong.

This model error can be seen by comparing Figures 1 and 2 below. They show the expected progression of the number of record daily temperatures with time (black curves) (note the number of expected daily records in any given year decreases with time). The red dots on Figures 1 and 2 represent the number of daily maximum temperature records set each year and the blue dots represent the number of daily minimum records. Figure 1 shows the observations, and Figure 2 shows the expectations from the NCAR climate model.

First let’s focus on the top graph in Figure 1 and see what the observations say is going on.

• with the exception of the 1960s and 1970s when fewer daily high temperature records were set than expected (the red dots fall below the black curve), for the most part, the number of daily high temperatures set each year falls off as the theory (which assumes no climate change) predicts it should (i.e. the red dots are pretty evenly distributed about the black curve).

• the observed data show that the number of daily minimum records being set (blue dots) is progressively falling further below the theoretical expectations. This confirms what we said earlier—that it is the decrease in minimum temperature records that is dominating the increase in the maximum/minimum temperature ratio.

Figure 1. Observed number of daily maximum (red dots) and daily minimum (blue dots) temperature records set each year across the United States, compared to expectations of assuming no temperature change (black curve). (Source: Meehl et al., 2009).

Now let’s have a look at what the NCAR model thinks should have been going on over the same time period. Notice in Figure 2 that the number of daily high temperatures progressively decrease less than expected under the assumption of no temperature change (red dots getting progressively higher than the black curve), while the number of expected minimum records decrease more than expected (blue dots progressively fall further below the black curve).

Figure 2. Projected number of daily maximum (red dots) and daily minimum (blue dots) temperature records set each year by the NCAR climate model, compared to expectations of assuming no temperature change (black curve). (Source: Meehl et al., 2009).

So while the observations suggest that our nights are warming faster than our days, this is not so in the NCAR climate model which suggests that the days and nights are warming up at the same rate. Such a model error leads to the model grossly overestimating the frequency and intensity of future heat waves.

Hopefully the powers-that-be in the EPA take note of this, because the specter of expanding heat waves in the future is something that the EPA highlights as it tries to justify regulating greenhouse gases under the Clean Air Act. Maybe they should go back and rethink that section as the climate models—or at least the NCAR climate model—fail to capture the behavior of the observations in this regard.

Repeat after us—if the models can’t replicate reality (for the right reasons) they can’t reliably predict the future.

So, the bottom line here is this—climate change in the U.S. during the past 50 years has resulted in fewer extreme nighttime low temperatures, while the daily extreme high temperatures have been little affected. And, at least one leading climate model fails to correctly capture this behavior.

Ask yourself this, is this the impression that you got from the coverage of this in the popular press?

References:

McKitrick, R. R., and P. J. Michaels, 2007. Quantifying the influence of anthropogenic surface processes inhomogeneities on gridded global climate data. Journal of Geophysical Research, 112, D24S09, doi:10.1029/2007JD008465.

Meehl, G. A., et al., 2009. The relative increase of record high maximum temperatures compared to record low minimum temperatures in the U.S., Geophysical Research Letters, doi:10.1029/2009GL040736, in press.

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42 thoughts on “More on the record high-low temperature debacle

  1. The one thing I read that stuck in my mind was that AGW would only induce a one degree change in nighttime temperatures, months ago. Forgot the source, seemed reasonable.
    It’s predicted to be 16F in sunny ,banana belt, Western Colorado tonight, bring on the warming!

  2. Well, if the current warm spell was near but not quite as high as the 1930’s-1940’s then this is exactly what I would expect. We would have fewer record lows because we are in a warm spell. We would have about the same number of record highs because we were at about the same temperature and because there are people living in places where towns didn’t exist in the 1930’s.
    The data appears to go to only 2004. Have things changed since 2005?

  3. No, the daytime highs are NOT becoming increasingly hotter.
    What they did was to truncate the records to start at time AFTER many of the extreme highs were set. So, they get new ones. But, the new highs that date back to the 1950’s are still not up to the dizzying heights recorded in the 20’s and 30’s.
    2nd thing that is happening is that the cheapie sensors out in the field that are swapped around when they fail are getting stuck. We saw it happen in Hawaii this year. I see it happening in my area too. The sensors are getting stuck high.
    All the while, our climate grows colder year on year.
    No, this is not real. It’s totally manufactured.
    Pineapple Upside-Down Yamal Mudpies.
    Anger is starting to grow over the obvious charade of false highs and the climate which is doing exactly opposite to what they are claiming.

  4. wakeupmaggy (21:19:53) :
    Kind of makes one very sore, to be shivering while fanboy climate forecasters are busy talking heat waves.

  5. I wonder if there’s a shift in geographical distribution too? I would expect fewer record lows to be set in ocean proximity during periods of higher SST.

  6. Rbateman (21:05:08) on manufacturing climate. I agree. I’ve said it before and I’ll say it again:
    “The spin doctors
    Of climatology
    Deny any bias
    In their new methodology.”

  7. Thomas (22:00:03) :
    Thanks for heads up on the starting up of the CLOUD experiment at CERN. Let us hope that the experiment will be unbiased and thorough.
    The Svensmark hypothesis on cosmic rays is so simple, but elegant in its explanation of how solar variation affects climate.
    From the CERN link it looks like we should be getting results as early as the startup with quantitative results following analysis. Quantitative will be good.

  8. Re Espen (22:33:02) :
    “Chiefio” aka E M Smith’s work suggests strongly that this is the case, thermometers are taking a dislike to being stuck up in mountains and the far north and are seeking warmer climates down south and at the beach!
    http://chiefio.wordpress.com/

  9. Warm nights are primarily created by cloud cover. So it there a similar report on the extent of night-time cloud cover?
    They seem to forget that the primary Greenhouse ‘Gas’ is water vapour and water droplets in the form of clouds. A thin cloud-deck just a couple of thousand feet thick can keep night temperatures 10 degrees c warmer than a clear sky.
    This paper seems to give a good overview of the water vapour problem.
    http://www.geocraft.com/WVFossils/greenhouse_data.html
    .

  10. It says a lot for their theories when they have to be so misleading. If global warming was such a obvious, factual and empirical hypothesis then you wouldn’t need any of this nonsense. As it is every year they have to keep reworking the numbers to make it look like in some way they actually may even possibly with a stretch of the imagination be right. But even then when you do a little due diligence (like you guys do here) its often shown to be blatantly wrong.

  11. I think this is another good reason why Global Average Temperature contains little information about the state of climate. Perhaps CO2 stops working during the day?

  12. Today here in Sydney, it was a bit warm, not overly so (For Western Sydney that is). Predictions of 40c+ inner west where I live and work, didn’t eventuate, actually it was about 33c. But I have noticed over the years that the 1/10th of a degree measurement seem to be rounded in the recorded mininums and maximums. Look here;
    http://weather.smh.com.au/local.jsp
    It will change. But “current” and “feels like” are not like recorded minimum and maximum, seems “rounded”, probably up.

  13. I think it’s fairly clear from the data (for example the long Central England Temperature series at http://hadobs.metoffice.com/hadcet/ that the main change in average temperatures has been a rise in the minimums, not a rise in the maximums. If you look at the seasonal data series it is quite noticeable that the winter is warmer, but there is not a large change in summer temperatures over quite a long time. I’ve not looked at the global data in this way, but would suspect that the same applies.

  14. Adam Gallon (00:28:10) : Ah, yes, I’ve read his blog, and I’m impressed by his work on GISS. But I think my question was poorly phrased: I was wondering if – given that thermometer sites stay in the same place – there was a shift towards less record lows among those thermometers that are close to the sea (but not among the inland ones).

  15. P Stanwards (03:16:14) : “… the main change in average temperatures has been a rise in the minimums, not a rise in the maximums. If you look at the seasonal data series it is quite noticeable that the winter is warmer, but there is not a large change in summer temperatures over quite a long time. I’ve not looked at the global data in this way, but would suspect that the same applies.
    I have checked out the maximum-temperature data for Australia (all weather stations going back 100+ years) and the same applies : summer maximum temperatures trend slightly down over the 100 years and winter maximum temperatures trend up.
    In Australia, as in the USA, the greatest number of all-time maximum temperatures fall in the 1930s decade.

  16. P Stanwards (03:16:14) :
    “… the main change in average temperatures has been a rise in the minimums, not a rise in the maximums. If you look at the seasonal data series it is quite noticeable that the winter is warmer, but there is not a large change in summer temperatures over quite a long time. I’ve not looked at the global data in this way, but would suspect that the same applies.”

    Mike Jonas (03:33:35) :
    I have checked out the maximum-temperature data for Australia (all weather stations going back 100+ years) and the same applies : summer maximum temperatures trend slightly down over the 100 years and winter maximum temperatures trend up.

    Doesn’t this suggest that the Sun is not a factor as a driver of climate change.

  17. OK, this is OT, but I wonder if anybody else saw the cool airburst in Northern New England this morning, a little after five a.m. Didn’t turn night into day, or anything, but it was many times brighter than Venus for a short instant of blue-white brilliance. Clearly visible through the window when no other stars were. I went outside to verify that it was actually a clear night.

  18. Tenuc (02:00:20) :
    I think this is another good reason why Global Average Temperature contains little information about the state of climate. Perhaps CO2 stops working during the day?

    It doesn’t say much for the Sun’s influence either. At least it could be argued that CO2 is most effective at night and in winter since it might slow down the rate of cooling, i.e. when outgoing energy exceeds incoming energy.

  19. The fact that the study doesn’t extend back to the period of greatest highs activity (30’s) explicates that there was no intention of scientific discovery in this work. It is predetermined propaganda, and because of this, all information therein is suspect, and not useful for any conclusions.

  20. Speaking of the 30’s:
    1932 09 04 9900 107 47 77.0 0.0 12.0 0.00 ####M ###M
    1932 09 05 9900 104 44 74.0 0.0 9.0 0.00 ####M ###M
    1932 09 06 9900 104 47 75.5 0.0 10.5 0.00 ####M ###M
    1932 09 07 9900 102 42 72.0 0.0 7.0 0.00 ####M ###M
    1932 09 08 9900 104 44 74.0 0.0 9.0 0.00 ####M ###M
    1932 09 09 9900 110 42 76.0 0.0 11.0 0.00 ####M ###M
    1932 09 10 9900 106 44 75.0 0.0 10.0 0.00 ####M ###M
    1932 09 11 9900 103 44 73.5 0.0 8.5 0.00 ####M ###M
    1932 09 12 9900 103 44 73.5 0.0 8.5 0.00 ####M ###M
    1932 09 13 9900 108 42 75.0 0.0 10.0 0.00 ####M ###M
    1932 09 14 9900 105 42 73.5 0.0 8.5 0.00 ####M ###M
    1932 09 15 9900 105 40 72.5 0.0 7.5 0.00 ####M ###M
    1932 09 16 9900 100 42 71.0
    It wasn’t just hot, it was bone dry. The diurnals speak of desert conditions in a forest.
    Weaverville, CA Ranger Station.

  21. John Finn (03:53:13) :
    It sure doesn’t say much for the Global Average temperature, and it says even less about Global Warming.
    It was hotter across the US in the 30’s because it was drier, and that concerns H20.
    There is no C02 Magic Carpet and Al Gore will not ascend into heaven after saving the Planet with Cap & Trade.

  22. Gee another present for Copenhagen, and there is no Pony under the tree,
    just a pile of fresh manure…

  23. “Anger is starting to grow over the obvious charade of false highs and the climate which is doing exactly opposite to what they are claiming.”
    Despite the NPR, NOAA, NCAR full court press, here in MN the ‘private’ media are panning AGW as one. Given three nights below -25 F, and three days above 90 F in the last 12 months, confidence in government is in free-fall.

  24. John Finn (03:53:13) : At least it could be argued that CO2 is most effective at night and in winter since it might slow down the rate of cooling, i.e. when outgoing energy exceeds incoming energy
    Except it doesn’t to any measure. Go to any desert or dry climate where it cools 40-50° every night. UHI is adding degrees and you’re hanging onto something that “might” have a fraction of a degree effect that can’t be observed? In that same dry climate place, lingering humidity after a rainshower, or thin high clouds can keep the night time heat loss to 10°. CO2 has no place on a scale of things that have a real world effect on climate.

  25. So we have had some cyclical warming that is coming to an end. I fail to see the dire conseqences that will lead to CAGW.
    The cyclical nature of the climate is the concensus position, because it has never been clearly rejected with real, reproducable evidence.
    The cycle has peaked and the propaganda will soon peak in an effort to deny the reality.

  26. Steve Keohane (08:17:06) :

    John Finn (03:53:13) : At least it could be argued that CO2 is most effective at night and in winter since it might slow down the rate of cooling, i.e. when outgoing energy exceeds incoming energy


    Except it doesn’t to any measure. Go to any desert or dry climate where it cools 40-50° every night. UHI is adding degrees and you’re hanging onto something that “might” have a fraction of a degree effect that can’t be observed? In that same dry climate place, lingering humidity after a rainshower, or thin high clouds can keep the night time heat loss to 10°. CO2 has no place on a scale of things that have a real world effect on climate.
    UHI is not an issue. Over the last 20 years satellite readings have measured the same warming as the surface records.
    The fact that the drier desert cools faster than more hiumid regions is tells us very little about the effectiveness of CO2.
    Russ R. (08:19:51) :
    So we have had some cyclical warming that is coming to an end.

    Is it? I reckon the next 5 years will be warmer than the last 5 years.

  27. Patrick Davis (03:09:08) :
    But I have noticed over the years that the 1/10th of a degree measurement seem to be rounded in the recorded mininums and maximums.
    …………………
    The other thing to notice Patrick is that when we have a day that looks like setting a cold record the BOM thermometer will all of a sudden ‘jump’ above the record minimum at Observatory Hill though the rest of the stations in Sydney remain FLAT.

  28. John Finn (10:54:41)
    “Is it? I reckon the next 5 years will be warmer than the last 5 years.”
    I hope you are right, John. A warm planet is more productive than a cold one. But this NCAR paper is no evidence of what will happen. It is meant for the AGW faithful, who are crying in their whine coolers over the pre-emptive failure of Copenhagen.
    There are many ways to massage numbers, and most of them have been used to keep this AGW balloon inflated. The key is the climate sensitivity to CO2. If it turns out to be low, then the balloon has to pop, no matter how you, or anyone else feels about it.

  29. Yes, but the Expected Count curve in Figure 1 does not fit the data. Most of the data points are below the line. Hence the Expected Count is over-predicted. Ergo, fewer records are being set than predicted by the Null Warming Model. If you credit this data with any veracity (a stretch due to UHI effect, false readings, etc.), the implication is that the climate is moderating (fewer records than expected).
    It is also interesting that from 1960 to 1980 the cold records outnumber the warm records. So that must have been a cooling period (given the questionable assumptions and data).

  30. Something I noticed immediately on the graphs you show – and it screams bad statistical practice out loud. The fitted theoretical curves have no ‘error’ envelope which would allow a viewer to visually assess any meaningful deviation of individual points.

  31. Meehl is a sophisticated player surviving (with grace actually – perhaps I should say “flourishing”) in a world of sharks & wolves. Let’s not forget the research he does on links between solar & hydrologic cycles (for which he needs to attract funding). My instinct is that there is a method to the recent (apparent) “madness”. Watch the way he smiles coyly in the video. This guy is capable of smoothly getting wool over the eyes of even the sharp – and additionally they won’t feel threatened by it because it comes with the polish of temporal restraint (i.e. they’ll trust him to apply “cordial” judgement in timing publicity of his findings on natural climate variation). As with Trenberth, I’m not writing this guy off because there may be opportunity to learn something important about natural climate cycles from these people, despite whatever political dances they may be doing to maintain secure funding-trains for their research programs on natural climate variation. Interesting psychologically, scientifically, politically… – layers of complexity.

  32. I burrowed through our local(Yes, I realize they’re local) record temperatures and had some similar findings. Instead of breaking them down by month, I used the seasons and broke them down further into warm(Spring/Summer and cool(Autumn/Winter). Our records are from 1893-Present and I divided them into four eras, 1893-1919(A), 20’s-40’s(B), 50s-1978(C) and 1979-Present(D).
    It gave a different look at what records were set during which periods.
    Highs:
    A-53.9% S/S, 46.1 A/W
    B-66.7% S/S, 33.3 A/W
    C-33.3% S/S, 66.7% A/W
    D-42.1% S/S, 57.9$ A/W
    Low highs:
    A-50% S/S, 50% A/W
    B-50% S/S, 50% A/W
    C-53.4% S/S, 46.6% A/W
    D-49.5% S/S, 50.5 A/W
    Lows:
    A-46.4% S/S, 53.6% A/W
    B-56.9% S/S, 43.1% A/W
    C-42.4% S/S, 57.6% A/W
    D-58.5% S/S, 41.5 A/W
    High lows:
    A-57.9% S/S, 42.1% A/W
    B-52.5% S/S, 47.5% A/W
    C-46.2% S/S, 53.8% A/W
    D-48.3% S/S, 51.7 A/W
    The number of records also shifted:
    Highs per year:
    A-2.8
    B-4
    C-2.6
    D-3.2
    High records are relatively constant except for era B, which included the 30’s.
    Low highs per year:
    A-3.4
    B-2.6
    C-3.6
    D-3.1
    Fairly constant.
    Lows per year:
    A-4.1
    B-3.9
    C-2.9
    D-1.8
    A measurable decline from B through C.
    High lows per year:
    A-2.8
    B-2.7
    C-2.2
    D-4.8
    So I saw the largest anomaly in record lows, which declined measurably and record high lows, which rose measurably. The only variables that stayed fairly constant were highs and low highs. I also noticed that more of the high records in recent years(D) occurred in autumn and winter and more of the low records were set in spring and summer.
    So it could be it’s not just the time of day when records are being set but also the time of year. (Again, I recognize this is just my little corner of the world.)
    Don’t be too hard on me, I’m just a middle aged guy with some time on my hands. 🙂

  33. Re: Greybrd (01:39:14)
    Thanks for sharing that.
    One of the patterns I noticed in your numbers has given me an insight into a regional TMin x TMax cross-wavelet analysis I ran more than a year ago (& shelved). [Btw: This raises very serious questions about homogenization-procedures.]
    I continue to find the 1920-1940 period fascinating.
    http://www.sfu.ca/~plv/PolarMotionPeriodMorlet2piPower.PNG
    http://www.sfu.ca/~plv/ChandlerPeriodAgassizBC,CanadaPrecipitationTimePlot.PNG
    http://www.sfu.ca/~plv/JN2&Pr.1840.png
    http://www.sfu.ca/~plv/MorletPi_Phase(Pr.-r..).png
    http://www.sfu.ca/~plv/TPM_SSD_LNC_3.png
    http://www.sfu.ca/~plv/Phase_JN_Pr..png
    http://www.sfu.ca/~plv/GA_MapXL_Line.PNG
    http://www.sfu.ca/~plv/CumuSumAMO.png
    http://www.sfu.ca/~plv/sqrtaayoy.sq22.png
    It is really unfortunate that many of our climate records do not extend back that far.

  34. I believe there is value to knowing ‘which’ records are broken. When were they set and what is the differential. As previously noted by others …. during a warm period (which we have warmed) it is less likely to break a cold record then a warm record.
    I think that if you tier periods…
    Early 1900’s = A
    Mid 1900’s = B
    Late 1900’s = C
    A high record set in A being broken in C by 0.1 to me has little meaning.
    A high record set in C and broken in C by 1.2 degrees would be more important, but, then I would have to consider ‘why’ (ie; ElNino, etc)
    A cold record set in A broken in C by any amount having significance and if broken with a fairly large differential then even more so.
    The probability of a record high set in A being broken in C is high.
    The probability of a record low set in A being broken in C is low.
    What about all time record highs by continent? Where do they stand?
    Highest temperatures recorded by continent:
    Africa – 136 – 1922
    North America – 134 – 1913
    Asia – 129 – 1942
    Australia – 128 – 1889
    Europe – 122 – 1881
    South America – 120 – 1905
    Oceania – 108 – 1912
    Antarctica – 59 – 1974
    It seems that each is a statistical anomaly relative to records in general.

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