AGW in Austin? (II)

I said this in “AGW in Austin?“:

There’s a rise in temperatures [in Austin] between the 1850s and the early 1890s, consistent with the gradual warming that followed the Little Ice Age. The gap between the early 1890s and mid-19naughts seems to have been marked by lower temperatures. It’s possible to find several mini-trends between the mid-19naughts and 1977, but the most obvious “trend” is a flat line for the entire period….

Following the sudden jump between 1977 and 1980, the “trend” remains almost flat through 1997, albeit at a slightly higher level….

The sharpest upward trend really began after the very strong (and naturally warming) El Niño of 1997-1998….

Oh, wait! It turns out that Austin’s sort-of hot-spell from 1998 to the present coincides with the “pause” in global warming….

The rapid increase in Austin’s population since 2000 probably has caused an acceleration of the urban heat-island (UHI) effect. This is known to inflate city temperatures above those in the surrounding countryside by several degrees.

What about drought? In Austin, the drought of recent years is far less severe than the drought of the 1950s, but temperatures have risen more in recent years than they did in the 1950s….

Why? Because Austin’s population is now six times greater than it was in the 1950s. The UHI effect has magnified the drought effect.

Conclusion: Austin’s recent hot weather has nothing to do with AGW.

Now, I’ll quantify the relationship between temperature, precipitation, and population. Here are a few notes about the analysis:

  • I have annual population estimates for Austin from 1960 to the present. However, to tilt the scale in favor of AGW, I used values for 1968-2015, because the average temperature in 1968 was the lowest recorded since 1924.
  • I reduced the official population figures for 1998-2015 to reflect a major annexation in 1998 that significantly increased Austin’s population. The statistical effect of that adjustment is to reduce the apparent effect of population on temperature — thus further tilting the scale in favor of AGW.
  • The official National Weather Service station moved from Mueller Airport (near I-35) to Camp Mabry (near Texas Loop 1) in 1999. I ran the regression for 1968-2015 with a dummy variable for location, but that variable is statistically insignificant.

Here’s the regression equation for 1968-2015:

T = -0.049R + 5.57E-06P + 67.8

Where,

T = average annual temperature (degrees Fahrenheit)

R = annual precipitation (inches)

P = mid-year population (adjusted, as discussed above)

The r-squared of the equation is 0.538, which is considerably better than the r-squared for a simple time trend (see the first graph below). Also, the standard error is 1.01 degrees; F = 2.96E-08; and the p-values on the variables and intercept are highly significant at 0.00313, 2.19E-08, and 7.34E-55, respectively.

Here’s a graph of actual vs. predicted temperatures:

Actual vs predicted average annual temperatures in Austin

The residuals are randomly distributed with respect to time and the estimated values of T, so there’s no question (in my mind) about having omitted a significant variable:

Average annual temperatures_residuals vs. year

Average annual temperaturs_residuals vs. estimates of T

Austin’s average annual temperature rose by 3.6 degrees F between 1968 and 2015, that is, from 66.2 degrees to 69.8 degrees. According to the regression equation, the rise in Austin’s population from 234,000 in 1968 to 853,000 (adjusted) in 2015 accounts for essentially all of the increase — 3.5 degrees of it, to be precise. That’s well within the range of urban heat-island effects for big cities, and it’s obvious that Austin became a big city between 1968 and 2015. It also agrees with the estimated effect of Austin’s population increase, as derived from the equation for North American cities in T.R. Oke’s “City Size and the Urban Heat Island.” The equation (simplified for ease of reproduction) is

T’ = 2.96 log P – 6.41

Where,

T’ = change in temperature, degrees C

P = population, holding area constant

The author reports r-squared = 0.92 and SE = 0.7 degrees C (1.26 degrees F).

The estimated UHI effect of Austin’s population growth from 1968 to 2015 is 2.99 degrees F. Given the standard error of the estimate, the estimate of 2.99 degrees isn’t significantly different from my estimate of 3.5 degrees or from the actual increase of 3.6 degrees.

I therefore dismiss the possibility that population is a proxy for the effects of CO2 emissions, which — if they significantly affect temperature (a big “if”) — do so because of their prevalence in the atmosphere, not because of their concentration in particular areas. And Austin’s hottest years occurred during the “pause” in global warming after 1998. There was no “pause” in Austin because its population continued to grow rapidly; thus:

12-month average temperatures in Austin_1903-2016

Bottom line: Austin’s temperature can be accounted for by precipitation and population. AGW will have to find another place in which to work its evil magic.

*     *     *

Related reading:
U.S. climate page at WUWT
Articles about UHI at WUWT
David Evans, “There Is No Evidence,” Science Speak, June 16, 2009
Roy W. Spencer, “Global Urban Heat Island Effect Study – An Update,” WUWT, March 10, 2010
David M.W. Evans, “The Skeptic’s Case,” Science Speak, August 16, 2012
Anthony Watts, “UHI – Worse Than We Thought?,” WUWT, August 20, 2014
Christopher Monckton of Brenchley, “The Great Pause Lengthens Again,” WUWT, January 3, 2015
Anthony Watts, “Two New Papers Suggest Solar Activity Is a ‘Climate Pacemaker‘,” WUWT, January 9, 2015
John Hinderaker, “Was 2014 Really the Warmest Year Ever?,” PowerLine, January 16, 2015
Roy W. Spencer, John R. Christy, and William D. Braswell, “Version 6.0 of the UAH Temperature Dataset Released: New LT Trend = +0.11 C/decade,” DrRoySpencer.com, April 28, 2015
Bob Tisdale, “New UAH Lower Troposphere Temperature Data Show No Global Warming for More Than 18 Years,” WUWT, April 29, 2015
Patrick J. Michaels and Charles C. Knappenberger, “You Ought to Have a Look: Science Round Up—Less Warming, Little Ice Melt, Lack of Imagination,” Cato at Liberty, May 1, 2015
Mike Brakey, “151 Degrees Of Fudging…Energy Physicist Unveils NOAA’s “Massive Rewrite” Of Maine Climate History,” NoTricksZone, May 2, 2015 (see also David Archibald, “A Prediction Coming True?,” WUWT, May 4, 2015)
Christopher Monckton of Brenchley, “El Niño Has Not Yet Paused the Pause,” WUWT, May 4, 2015
Anthony J. Sadar and JoAnn Truchan, “Saul Alinsky, Climate Scientist,” American Thinker, May 4, 2015
Clyde Spencer, “Anthropogenic Global Warming and Its Causes,” WUWT, May 5, 2015
Roy W. Spencer, “Nearly 3,500 Days since Major Hurricane Strike … Despite Record CO2,” DrRoySpencer.com, May 8, 2015

Related posts:
AGW: The Death Knell (with many links to related readings and earlier posts)
Not-So-Random Thoughts (XIV) (second item)
AGW in Austin?
Understanding Probability: Pascal’s Wager and Catastrophic Global Warming
The Precautionary Principle and Pascal’s Wager

AGW in Austin?

“Climate change” is religion refracted through the lens of paganism.

Melanie Phillips

There is a hypothesis that the purported rise in global temperatures since 1850 (or some shorter span if you’re embarrassed by periods of notable decline after 1850) was or is due mainly or solely to human activity, as manifested in emissions of CO2. Adherents of this hypothesis call the supposed phenomenon by various names: anthropogenic global warming (AGW), just plain global warming, climate change, and climate catastrophe, for example.

Those adherents loudly advocate measures that (they assert) would reduce CO2 emissions by enough to avoid climatic catastrophe. They have been advocating such measures for about 25 years, yet climate catastrophe remains elusive. (See “pause,” below.) But the true believers in AGW remain steadfast in their faith.

Actually, belief in catastrophic AGW requires three leaps of faith. The first leap is to assume the truth of the alternative hypothesis — a strong and persistent connection between CO2 emissions and global temperatures — without having found (or even looked for) scientific evidence which disproves the null hypothesis, namely, that there isn’t a strong and persistent connection between CO2 emissions and global temperatures. The search for such evidence shouldn’t be confined to the near-past, but should extend centuries, millennia, and eons into the past. The problem for advocates of AGW is that a diligent search of that kind works against the alternative hypothesis and supports the null hypothesis. As a result, the advocates of AGW confine their analysis to the recent past and substitute kludgy computer models, full of fudge-factors, for a disinterested examination of the actual causes of climate change. There is strong evidence that such causes include solar activity and its influence on cloud formation through cosmic radiation. That truth is too inconvenient for the AGW mob, as are many other truths about climate.

The second leap of faith is to assume that rising temperatures, whatever the cause, are a bad thing. This, despite the known advantages of warmer climates: longer growing seasons and lower death rates, to name but two. This is so because believers in AGW and policies that would (according to them) mitigate it, like to depict worst-case scenarios about the extent of global warming and its negative effects.

The third leap of faith is related to the first two. It is the belief that policies meant to mitigate global warming — policies that mainly involve the curtailment of CO2 emissions — would be (a) effective and (b) worth the cost. There is more than ample doubt about both propositions, which seem to flow from the kind of anti-scientific mind that eagerly embraces the alternative hypothesis without first having disproved the null hypothesis. It is notable that “worth the cost” is a value judgment which springs readily from the tongues and keyboards of affluent Westerners like __________ who already have it made. (Insert “Al Gore”, “high-end Democrats,” “liberal pundits and politicians,” etc.)

Prominent among the leapers-of-faith in my neck of the woods is the “chief weathercaster” of an Austin TV station. We watch his weather forecasts because he spews out more information than his competitors, but I must resist the urge to throw a brick through my TV screen when his mask slips and he reveals himself as a true believer in AGW. What else should I expect from a weather nazi who proclaims it “nice” when daytime high temperatures are in the 60s and 70s, and who bemoans higher temperatures?

Like any nazi, he projects his preferences onto others — in this case his viewership. This undoubtedly includes a goodly number of persons (like me) who moved to Austin and stay in Austin for the sake of sunny days when the thermometer is in the 80-to-95-degree range. It is a bit much when temperatures are consistently in the high 90s and low 100s, as they are for much of Austin’s summer. But that’s the price of those sunny days in the 80s and low 90s, unless you can afford to live in San Diego or Hawaii instead of Austin.

Anyway, the weather nazi would make a great deal out of the following graph:

12-month average temperatures in Austin_1977-2015

The graph covers the period from April 1977 through April 2015. The jagged line represents 12-month averages of monthly averages for the official National Weather Service stations in Austin: Mueller Airport (until July 1999) and Camp Mabry (July 1999 to the present). (There’s a history of Austin’s weather stations in a NOAA document, “Austin Climate Summary.”) The upward trend is unmistakeable. Equally unmistakeable is the difference between the early and late years of the period — a difference that’s highlighted by the y-error bars, which represent a span of plus-and-minus one standard deviation from the mean for the period.

Your first question should be “Why begin with April 1977?” Well, it’s a “good” starting point — if you want to sell AGW — because the 12-month average temperature as of April 1977 was the lowest in 64 years. After all, it was the seemingly steep increase in temperatures after 1970 that sparked the AGW business.

What about the “fact” that temperatures have been rising since about 1850? The “fact” is that temperatures have been recorded in a relatively small number of locales continuously since the 1850s, though the reliability of the temperature data and their relationship to any kind of “global” average is in serious doubt. The most reliable data come from weather satellites, and those have been in operation only since the late 1970s.

A recent post by Bob Tisdale, “New UAH Lower Troposphere Temperature Data Show No Global Warming for More Than 18 Years” (Watts Up With That?, April 29, 2015), summarizes the history of satellite readings, in the course of documenting the “pause” in global warming. The “pause,” if dated from 2001, has lasted 14 years; if dated from 1997, it has lasted 18 years. In either event, the “pause” has lasted about as long as the rise in late-20th century temperatures that led to the AGW hypothesis.

What about those observations since the 1850s? Riddled with holes, that’s what. And even if they were reliable and covered a good part of the globe (which they aren’t and don’t), they wouldn’t tell the story that AGW enthusiasts are trying to sell. Take Austin, for example, which has a (broken) temperature record dating back to 1856:

12-month average temperatures in Austin_1856-2015

Looks just like the first graph? No, it doesn’t. The trend line and error bars suggest a trend that isn’t there. Strip away the trend line and the error bars, and you see this:

12-month average temperatures in Austin_1856-2015_2

Which is what? There’s a rise in temperatures between the 1850s and the early 1890s, consistent with the gradual warming that followed the Little Ice Age. The gap between the early 1890s and mid-19naughts seems to have been marked by lower temperatures. It’s possible to find several mini-trends between the mid-19naughts and 1977, but the most obvious “trend” is a flat line for the entire period:

12-month average temperatures in Austin_1903-1977

Following the sudden jump between 1977 and 1980, the “trend” remains almost flat through 1997, albeit at a slightly higher level:

12-month average temperatures in Austin_1980-1997

The sharpest upward trend really began after the very strong (and naturally warming) El Niño of 1997-1998:

12-month average temperatures in Austin_1997-2015

Oh, wait! It turns out that Austin’s sort-of hot-spell from 1998 to the present coincides with the “pause” in global warming:

The pause_from WUWT_20150429
Source: Bob Tisdale, “New UAH Lower Troposphere Temperature Data Show No Global Warming for More Than 18 Years,” Watts Up With That?, April 29, 2015.

What a revolting development this would be for our local weather nazi, if he could be bothered to acknowledge it. And if he did, he’d have to look beyond the egregious AGW hypothesis for an explanation of the warmer temperatures that he abhors. Where should he look? Here: the rapid increase in Austin’s population, combined with a drought.

The rapid increase in Austin’s population since 2000 probably has caused an acceleration of the urban heat-island (UHI) effect. This is known to inflate city temperatures above those in the surrounding countryside by several degrees.

What about drought? In Austin, the drought of recent years is far less severe than the drought of the 1950s, but temperatures have risen more in recent years than they did in the 1950s:

Indices of 5-year average precipitation and temperature

Why? Because Austin’s population is now six times greater than it was in the 1950s. The UHI effect has magnified the drought effect.

Conclusion: Austin’s recent hot weather has nothing to do with AGW. But don’t try to tell that to a weather nazi — or to the officials of the City of Austin, who lurch zombie-like onward in their pursuit of “solutions” to a non-problem.

BE SURE TO READ THE SEQUEL, IN WHICH I QUANTIFY THE EFFECTS OF PRECIPITATION AND POPULATION, LEAVING NOTHING ON THE TABLE FOR AGW.

*     *     *

Related reading:
U.S. climate page at WUWT
Articles about UHI at WUWT
Roy W. Spencer, “Global Urban Heat Island Effect Study – An Update,” WUWT, March 10, 2010
Anthony Watts, “UHI – Worse Than We Thought?,” WUWT, August 20, 2014
Christopher Monckton of Brenchley, “The Great Pause Lengthens Again,” WUWT, January 3, 2015
Anthony Watts, “Two New Papers Suggest Solar Activity Is a ‘Climate Pacemaker‘,” WUWT, January 9, 2015
John Hinderaker, “Was 2014 Really the Warmest Year Ever?,” PowerLine, January 16, 2015
Roy W. Spencer, John R. Christy, and William D. Braswell, “Version 6.0 of the UAH Temperature Dataset Released: New LT Trend = +0.11 C/decade,” DrRoySpencer.com, April 28, 2015
Bob Tisdale, “New UAH Lower Troposphere Temperature Data Show No Global Warming for More Than 18 Years,” WUWT, April 29, 2015
Patrick J. Michaels and Charles C. Knappenberger, “You Ought to Have a Look: Science Round Up—Less Warming, Little Ice Melt, Lack of Imagination,” Cato at Liberty, May 1, 2015
Mike Brakey, “151 Degrees Of Fudging…Energy Physicist Unveils NOAA’s “Massive Rewrite” Of Maine Climate History,” NoTricksZone, May 2, 2015 (see also David Archibald, “A Prediction Coming True?,” WUWT, May 4, 2015)
Christopher Monckton of Brenchley, “El Niño Has Not Yet Paused the Pause,” WUWT, May 4, 2015
Anthony J. Sadar and JoAnn Truchan, “Saul Alinsky, Climate Scientist,” American Thinker, May 4, 2015
Clyde Spencer, “Anthropogenic Global Warming and Its Causes,” WUWT, May 5, 2015
Roy W. Spencer, “Nearly 3,500 Days since Major Hurricane Strike … Despite Record CO2,” DrRoySpencer.com, May 8, 2015

Related posts:
AGW: The Death Knell (with many links to related readings and earlier posts)
Not-So-Random Thoughts (XIV) (second item)

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