A favorite tactic of those who deny global warming is to exagerate the importance of the temperature record of the contiguous United States (the lower 48 states of the continental USA). It’s only 1.6% of the surface area of the planet, so it’s not truly representative of the globe as a whole. But what the heck, it is part of planet earth, so it’s interesting to examine the temperature history of the contiguous U.S., aka the “lower 48 states,” aka “USA48.”

Another recurring tactic is to portray USA48 temperature change (and other things too) unrealistically. For instance, Steven Goddard actually claimed that most of the USA isn’t warming at all. The National Climate Data Center reports temperature from 1895 to the present for the lower 48 states, as well as the entire contiguous U.S. and various regions of same. Here are annual average temperature anomalies (using the entire time span as a baseline) for USA48:

Here are the trend rates for each of the 48 states, plotted on a longitude-latitude grid, warming trends shown as red dots and cooling trends as blue dots, with larger dots indicating larger trends:

Notice: there are very few blue dots, and they’re all small.

If we consider the trend rates from 1975 to the present for each of the 48 states, the warming is even more pronounced. Here are warming trends shown as red dots and cooling trends as blue dots, with larger dots indicating larger trends:

Notice: there aren’t any blue dots.

Chip Knappenberger chimes in with his temperature update for the USA only. He starts by showing only data through 1997, dropping the hot years which followed, and claiming that:

… there was really not much worth writing home about—there were signs of inter-decadal variability, but nothing that seemed to scream “dangerous anthropogenic global warming!” The overall upward trend was being driven more by cool conditions in the early decades of the record, rather than warm conditions at the end of the record.

Let’s add a smooth curve (in red), and a trend line (in blue), to that 1895-1997 data:

It sure looks like the overall upward trend was driven by warm conditions at the end of the record. Let’s reduce the noise by plotting, not 1-year averages, but 10-year averages:

No doubt about it, the trend comes not just from “cool conditions in the early decades of the record,” but also from “warm conditions at the end of the record.” And that’s ignoring everything from 1998 onward.

Splitting the record into pieces at 1998 is yet another common tactic. Not only does doing so omit the extreme 1998 rise from earlier data, it also makes for an artificially high starting point for subsequent data — kinda like tracking the heights of men walking through a doorway but deliberately starting with Shaquille O’Neal, because you know that whoever comes afterward is likely to be shorter. Should we take to calling that tactic the “Shaq attack”?

Starting with 1998, temperatures in the USA48 were way higher. Here are the decadal averages for the full record, from 1895 to the present:

The final average includes only two years, 2010 and 2011. It’s not as hot as the searing 2000s, but it’s still the 2nd-hottest decade on record so far, an inauspicious beginning to the new decade. Nonetheless, since the last few years weren’t as hot as the decade 1998-2007, Chip wants to portray 1998-2007 as “unusual” and what followed as some sort of “recovery.” His post was written in mid-2011, so he even goes so far as to use the first 6 months of 2011 to forecast that the final 2011 result is likely to be less than 2010:

And how did 2011 actually turn out? As you can see from the first figure in this post, it ended up hotter than 2010 for USA48.

It’s curious that Chip Knappenberger placed so much emphasis on the result of a single year, or even a few years, especially since the temperature over a small fraction of the globe (a mere 1.6%) shows so much more variation than the global average. The fact is that a single year, unless it’s so far out of bounds as to be astounding, isn’t going to tell us a whole lot. Focusing on a time span which is far to short to be meaningful just might be the fake skeptics’ favorite tactic of all.

Clearly, over the long haul it has gotten hotter here in the USA48. But if you listen to the wrong people, you might get the wrong impression about that.

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19 responses to “USA48

  1. i think you mean Chip wrote his post in mid 2011.

    [Response: Right you are. Fixed.]

  2. You quote Chip as saying “The overall upward trend was being driven more by cool conditions in the early decades of the record, rather than warm conditions at the end of the record.”

    Isn’t that kind of like saying “the difference between 1 and 2 isn’t important, because it’s driven by 1 being less than 2, rather than 2 being less than 1″???

    Needless, to say, the recent temperatures are well above nearly everything else – you’ve got to do some serious cherry picking to get anything close to what Chip seems to want to believe.

  3. “The overall upward trend was being driven more by cool conditions in the early decades of the record, rather than warm conditions at the end of the record.”

    Now that one rates a “liar, liar, pants on fire” rating. Not only is it not true (as shown in the post), but the presence of a few small ‘blue dots’ of cooling in Figure 2 is primarily due to warmtemperatures in the Southeast at the beginning of the record. That’s why those dots ‘turn red’ in Figure 3, when the early part of the record isn’t considered.

  4. Is Chip a gardener? What’s he going to do when he sees the back of the seed packet telling him that the climatic “hardiness” zones have shifted throughout these non-changing United States. Perhaps he thinks kudzu will be a decorative boon to New England landscapes.

    • We had a crocus bloom. 4 days ago!

    • Horatio Algeranon

      Chip is that rarest of gardeners who yanks out all the cultured flowers and vegetables and then proceeds to cultivate the weeds.

      And 1998 was a particularly good year for weeds.

      The Dandy Lyin has never been bigger.

    • Last week, in northern Missouri, I took the twins out for a stroll in their red wagon. I set the boy down on the grass and picked him back up almost immediately. There were thousands of spiders crawling all over everything. They weren’t just in one spot, either. Baby spiders crawling around during the allegedly coldest part of winter. We’ll be in the 50s (F) all week this week.

  5. Hmmm… This might be of interest then:


  6. I don’t know if you were aware of it, adelady, but kudzu has made it to southwestern Ontario, if not New England. So far, it’s just a struggling little outlier patch, managing to hang on in the face of eradication efforts, but not really thriving. For now. . .

    • Bloody hell! I thought we had a few years before it turned up.

      I was mentioning Kudzu to a friend this afternoon and said I thought we had 10-15 years before it appeared.

      Of course, I’m from Kingston so we probably have a couple of years left!

      • Yeah, the only known patch is near Leamington, so you’ve got a separation of what, maybe 400-450 km? Plus, Kingston is distinctly colder than the southwestern peninsula.

        And who knows? Maybe the GTA has some value as a buffer!

  7. “Steven Goddard actually claimed that most of the USA isn’t warming at all.”

    He actually claimed it had cooled since 1895! This was in a post his called his 2012 Global Warming Report Card;

    I rebutted the whole thing here;
    And went into more details on how he handled this issue here;

    Which prompted the post from him that you have linked too, calling on me for a retraction, along with some childish name calling. In the end he was told by a commentator how he had coloured all the grey neutral areas bright blue when they did not indicate warming at all and ended up retracting!

    I will link to this post from my own as you have dealt with the it better than I.

  8. Here in East TN crocus was blooming at least two weeks ago and insects on plants in the garden around Xmas.

  9. Off topic, perhaps for a new open thread?

    Does anyone else note the similarity between this (published 01/25/2012);

    and this (published 01/29/2012);

    These two plots are virtually identical. Sheer coincidence? I doubt it.

    Some background;–Cycle-25-need-worry-NASA-scientists-right-Thames-freezing-again.html

    My conjecture would be that this is a fabricated story using David Archibald data/plots and/or WTFUWT? data/plots as shown in the David Rose article. Either that, or DR lifted this plot from WTFUWT? without attribution, as I can’t find a similar graphic anywhere else.

  10. This might be of interest here …

    And yes, I am the third author on the paper …

  11. Tamino,

    Beyond appreciation for this the post, added thanks for the 1st paragraph. Contiguous U.S. is the accurate term. Using “the lower 48″ ignores Hawaii which is the southern most State, and Alaska realty is part of the North American Continent despite Sara Palin. USA48 is a new one to me but works just fine. Your coinage?