Joe D’Aleo suggested earlier today that I take a look at some of the data from NCDC’s web page called “US climate at a glance“. This page allows comparisons of the actual data not anomalies used in the NCDC USHCN Surface temperature network. The NCDC web page allows you to compare and not only the nation but states and cities as well using the actual USHCN data. Joe’s interest was the urban heat island effect (UHI) in cities in Texas. First let’s take a look at the state of Texas itself for the last 100 years:
Source: http://www.ncdc.noaa.gov/oa/climate/research/cag3/tx.html
As you can see the trend is essentially flat, with the trend equaling 0.01F Per decade over the last 100 years. That trend by itself is interesting, but there’s a lot more of interest when you look at the cities individually.
Here is a list of cities in Texas based on population size, this table is from Wikipedia:
| Rank | Population | Place name |
|---|---|---|
| 1 | 2,099,451 | Houston |
| 2 | 1,327,407 | San Antonio |
| 3 | 1,197,816 | Dallas |
| 4 | 790,390 | Austin |
| 5 | 741,206 | Fort Worth |
| 6 | 649,121 | El Paso |
| 7 | 365,438 | Arlington |
| 8 | 305,215 | Corpus Christi |
| 9 | 259,841 | Plano |
| 10 | 236,091 | Laredo |
| 11 | 229,573 | Lubbock |
| 12 | 226,876 | Garland |
| 13 | 216,290 | Irving |
| 14 | 190,695 | Amarillo |
The third largest city in Texas by population is of course Dallas. Unfortunately, Dallas only has data going back to 1948 according to the NCDC pages that allow selection. So will use 1948 as a starting point for comparison, here then is the statewide trend since 1948:
The Decadal scale trend from 1948 to 2011 is 10 times larger than that of the last 100 years at 0.10 Fahrenheit per decade.
Now let’s look at major cities in Texas available from the NCDC cities page, first Dallas:
Source: http://www.ncdc.noaa.gov/oa/climate/research/cag3/city.html
The decadal-scale trend in Dallas is almost three times larger than that of the state of Texas at 0.28 Fahrenheit per decade.
Now let’s have a look at the largest city in Texas, Houston:
Being the largest city, one might expect that Houston would have a larger trend than Dallas, however it should be noted that Houston has a strong ocean influence from the Gulf of Mexico. So, one would expect that it’s trend would be muted compared to an inland city.
Corpus Christi is another Texas city that has an ocean influence. It’s decadal-scale trend is also somewhat muted by comparison:
It is also a significantly smaller city with less growth:
San Antonio however being the second largest city is well inland away from the ocean – look at its trend:
At 0.41 Fahrenheit per decade, it is four times larger than the statewide trend from 1948 to 2011. The population of San Antonio looks like a hockey stick, especially after 1940:
According to the Wikipedia entry on San Antonio: “It was the fastest growing of the top 10 largest cities in the United States from 2000-2010, and the second from 1990-2000.”. So I suppose it is no surprise to find it having such a large temperature trend compared to other Texas cities and the state itself.
El Paso, TX:
Like Corpus Christi, El Paso didn’t grow quickly either.
Amarillo:
Amarillo didn’t see wild growth like San Antonio.
So what can we conclude from all of these comparisons? First, I’d like to point out that this is not a definitive comparison, as it is lacking many of the cities in Texas but these are the cities that were available from the NCDC page.
But, what we can conclude with certainty is that all of the (available) cities plotted from NCDC Data at “US climate at a glance” show a decadal-scale trend that is larger than the decadal-scale trend for entire state of Texas for the same period. Of course, Texas being composed of wide open range has many USHCN stations that are not in populated areas. Thus, it is not surprising to see that the state of Texas has very little trend while Texas cities have a significantly greater trend.
Dr. Roy Spencer has found more UHI examples in Roy Spencer’s ISH population adjusted discoveries. He writes:
The bottom line is that there is still clear evidence of an urban heat island effect on temperature trends in the U.S. surface station network. Now, I should point out that most of these are not co-op stations, but National Weather Service and FAA stations. How these results might compare to the GHCN network of stations used by NOAA for climate monitoring over the U.SA., I have no idea at this point.
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@Joe Kirklin D’Aleo
> Thus, it is not surprising to see that the state of Texas has very
> little trend while Texas cities have a significantly greater trend.
So, Joe, would it be fair to say that you agree, qualitatively, with the AGW crowd that ‘man-made activities’ (i.e. urban heat islands) have created measurable increases in Texas temperatures over the past century. But you disagree, quantitatively, on how those increases are distributed?
REPLY: Joe didn’t write that, I did. I disagree with the way the data is homogenized, combining the good stations with the bad ones for a smeared around data result that is claimed to be representative – Anthony
In the 1970’s oil shock the idea of “thermal mass” for storing energy/heat was talked about a great deal. Cities by their very existance have thermal mass. Black top roads and concrete buildings who would have thought they can get hotter than grass and trees. Ever listen to an announcer tell you the temperature on a baseball field at stadiums with artificial turf?
The other side of the coin is the data from sites NOT in/near UHIs. In Texas this would mean sites not near the cities listed above, those with about 200,000 or more population. What do the temperature data show for these sites?
More data to back up E M Smith’s great work, and suggest to Steve Mosher that although his sums are fine, his parameters need re-examination perhaps.
And of course, a whole pageful of UHI studies here. I shall now add Anthony’s excellent study here to that page as soon as I get a chance – and as soon as I can cope better with my own arm RSI. Thank you again Anthony for keeping this important issue up front. Hope your own hand healing process is being protected from further strain.
This post goes to the heart of my argument: the inconsistency of CO2-caused warming. If little warming is shown state-wide, yet the big cities are rapidly warming, then many places must be cooling.
Why does CO2 allow those non-urban areas to cool?
See http://sowellslawblog.blogspot.com/2012/05/warmists-are-wrong-cooling-is-coming.html
And the portion following:
“This is from Abilene, Texas which is right out in the middle of the state, a little bit west of Dallas. It shows absolutely no warming whatsoever for the past 110 years or so. The slope here, and you probably cannot read that, is actually negative. It is -0.19° per century, round it off -0.2. From an earlier slide [Figure 1], remember we were looking at a warming trend of about 0.6° per century, which is what the warmists are saying. I want to know why it ignored Abilene?”
Kristen Byrnes (Ponder the Maunder) — 1
Al Gore (Post Turtle) — 0
It’s official, CO2 causes *extreme* population growth.
😉
Like Tadchem, I reckon that if all major cities show a greater temperature rise than the State as a whole, then rural areas must show a decline. The only way to display global temperatures is to eliminate all urban sites. That blows AGW out of the water.
with TX cities, you also have to consider the huge amount of growth in the suburbs outside the city limits. the last 15 years has seen a large influx of people to the states major metro areas. in Houston, you can see where large areas, 20-30 miles out from the city, that used to be woods in the 90’s are now parking lots, subdivisions and strip malls…
Without looking at the data – is it that in rural areas that temperature has shown little or no change and that ‘adjustments’ for UHI are far, far less than the recorded amount of change when compared to rural temperatures thus leading to the deceptive appearance that Texas has seen a rise in temperature ?
Be interesting to see unadjusted average temperatures of the rural areas plotted against the same in urban areas to see how far off the ‘adjustments’ for UHI are in Tx.
The trend may look flat. But just wait until the past gets cooler.
Take the data from the top cities out and see what happens for the rest of the state.
Perhaps there are better ways to handle UHI that are better than a simple across the board CO2 type tax
John Day: ” ‘man-made activities’ (i.e. urban heat islands) have created measurable increases in Texas temperatures over the past century”
Don’t confuse temperatures of Texas cities with temperatures of the state of Texas. Just because the roof of your house is very hot does not mean that your backyard is the same temperature.
KTWO says:
June 28, 2012 at 11:12 am
“The trend may look flat. But just wait until the past gets cooler.”
As I noted in another post, even the Weather Channel had a brief item last night re the UHI phenomina though, at least in the part I saw, did not relate it back to the mismeasurement of overall temperatures. The past may not get cooler in the UHI areas as concrete and roof areas increase over time.
Somewhat OT, but the SCOTUS ruling on the AHCA today dealt a blow to using the Commerce Clause indiscriminately. This will have widespread ramifications on various regulatory agencies who rely on it as their legal right to regulate many things. Including issues related to food, farming, water, etc. We’ll have to wait and see, but I think it will be of benefit in reining in the EPA, USDA, and others.
Of course, you know that the UHI effect can be seen as evidenced in the higher-res IR satellite imagery for some of these cities (like Dallas) as evening turns into night and radiative cooling takes place in the countryside …
.
This is pretty good data as it puts a few myths to rest.
1. Most studies of UHI ( like Oke ) focus on UHI MAX. that is the maximum UHI that
a city can see. To do this researchers cherry pick the days to study. They study
days that have the optimal synoptic conditions for UHI: no wind, no clouds, no precipitation
in the previous days leading up to the observation. This is all well and good for capturing
the maximum, and you will see figures like 2C, 4C, and higher. But this is not average
UHI. Average UHI is what biases the record so we need a good estimate of the average
which means we need to look over time.
2. Its unfortunate that the data was presented in F. But we can fix that. First thing we have to note is what the literature already shows for a range of UHI Bias. Now most of this
is for large cities, but generally the bias is anywhere between .05C per decade to .125C
per decade for cities and regions such as : large US cities, tiawan, korea, china, japan,
and London.
What do we find in texas for 1948 through present, a baseline trend of .1F decade
for a quick and dirty estimate of the UHI bias added above this trend we have
Dallas: UHi ads approx .1C per decade
Houston: around .05C
Corpus Cristi : < .03C decade
San antonio: .15C per decade
El Paso and amerillo.. lost in the noise.
With the exception of San Antonio all are within previous estimates. It would be interesting
for example, to see what happens to the average in texas ( and the world) if you remove
all cities larger than 10,000. Another way to look at it is this. If we make one pile
of all the stations that have tiny populations ( less than 10 people/sq km ) and
another pile of all the other stations ( on average 500 people per sq km).. the UHI
Bias is on the order of .04C per decade. ( Hausfather & Mosher)
As a side note population density in places like dallas and san antonio is on the
order of several thousands per sq mile ( and 1-3 thousand per sq km ) far above the
average of all stations.
The other things we see of course is that other factors ( such as distance from coast )
can really drive UHI. For the global database, therefore its good to remember that a good majority of human population lives on the coast in coastal cities. consequently in the global database its important to realize that the total effect of UHI can be muted by city location.
the more cities in your database that are on the coast the lower your UHI bias.
The other really important factor here is that UHI is also known to be much higher in northern latitudes than in southern latitudes. Texas is a northern latitude location.
An one last thing to note is that while a "log" curve is a good approximation for
UHI MAX for large cities, the data here ( UHI average ) indicates, as does other research,
that average UHI is not easily modelled as a function of population. Oke himself realized this and modified his formula to take regional windspeed into account as well as the regional building practice. Large population in high rises exhibit the highest UHI whereas large populations spread out in sprawling cities have lower UHI. Basically building height matters ( statistically it matters more than other factors ) Specicially aspect ratio matters.
( compare the aspect ratios of dallas and san antonio for example) and its also clear why san antonio would tend to have the higher UHI
Finally, all of these cities are large population. you dont see any "village UHI" here and what the data seems to indicate ( if you plot UHI versus change in population ) is that the bias
vanishes as you go to smaller and smaller populations.
As an example: in the Berkeley Earth dataset, around 10000 stations have zero population.
You can in fact build a global database where there are no large cities, no medium sized cities, no small cities,..
“So, Joe, would it be fair to say that you agree, qualitatively, with the AGW crowd that ‘man-made activities’ (i.e. urban heat islands) have created measurable increases in Texas temperatures over the past century. But you disagree, quantitatively, on how those increases are distributed?”
Man caused, yes.
CO2 caused, no.
So controlling CO2 is the wrong solution for this problem.
Good vs. Bad stations? There are a bunch of people in these rapidly growing cities that care about how hot it is in those cities. Temperature measurements in those cities are valid for those cities for many purposes – not just dithering about global warming. To exclude temperatures from where millions of people live because millions of people live there seems a little absurd.
In arguing for a UHI, this article compares absolute temperature records when temperature anomoly records are used to determine GW.
Why are you using absolute temperature instead of temperature anomoly? Here is NOAA’s explanation of why anomoly is superior: http://www.ncdc.noaa.gov/cmb-faq/anomalies.php go to question 7.
It would be very interesting to discuss why NOAA’s methodology does not account for UHI. Here is how they address it: http://www.ncdc.noaa.gov/oa/climate/research/ushcn/#urbanization
Intersting, I just moved to Corpus Christi – With so much air moving in the city from the ocean, you can see while driving the change in temperature as you drive through the town, but it isn’t much.
Driving into San Antonio, your A/C sound will change, it is almost a line you cross. The town is significantly hotter from outside the city limits compared to inside. You can feel the difference.
0 population doesn’t mean no UHI. Airports don’t have any population.
What seems to be missing in the discussion of UHI is that it is not just a factor of population. The radical increase in air conditioning and use of asphalt in the 1965-1985 time slot (for the US at least) would give a much larger anomaly jump during those years. Any study that looks at a different time period to calculate an average UHI would miss this.
SocialBlunder says:
“To exclude temperatures from where millions of people live because millions of people live there seems a little absurd.”
What’s absurd is taking a temperature (absolute or anomaly) increase that has been artificially increased due to population increase and attributing that increase to “enhanced greenhouse effect”; excluding those temperatures is the exact opposite of absurd.
There are other local factors at play in addition to population. As this map that Muller produced shows, there are many stations with warming trends next door to ones with cooling.
Simply averaging them all together is nonsense.
http://notalotofpeopleknowthat.wordpress.com/2011/10/22/kansas-temperature-trend-updatemuller-confirms-there-is-a-problem/