Premature Climate Alarmism in Austin

The New York Times is reporting on a study the city of Austin, Texas commissioned to examine the potential impacts of climate change in the city.

According to the article:

The study, which was done by the scientific research and consulting firm Atmos, also found that while Austin would probably experience longer dry spells and receive less rain over all, it would be hit more frequently with 'extreme precipitation' events that could lead to widespread flooding. City departments recently asked the City Council for more than $650,000 for detailed assessments of how climate change could affect Austin’s infrastructure, from its water reservoirs and power plants to its parks.

That's an interesting prediction, given how there has been no significant trend in Austin's summertime precipitation since records began in 1898.  In fact, the correlation is positive, toward more rain in the summer.  Similarly, no significant trend since 1970, either, and another positive correlation – not negative.  No significant trend over the past 30 years as well.

There has been no trend in Austin's annual precipitation since the late 1800s.  It's almost a perfect non-correlation.  Since 1970, there is also no significant trend, and we see a positive – not negative – correlation.  Essentially a perfect non-correlation over the past three decades, too.

Overall, there is absolutely no sign that the amount of summertime or annual precipitation in Austin is changing.  This contrasts sharply with predictions that “Austin would probably ... receive less rain over all.”

And apparently Austin will “be hit more frequently with 'extreme precipitation' events that could lead to widespread flooding.”  The report itself states the following on this subject: “The number of days per year with more than 2 inches of rainfall is projected to increase by about +1 day in every 2 years by end of century.”

Here is the historical record of number of days per year with more than 2 inches of precipitation in Austin since 1898.

There is no significant trend, and the correlation is actually negative towards fewer days of extreme precipitation each year, not more.  No significant trends since 1970 or during the past 30 years, either.  So if anthropogenic climate change is supposed to lead to a substantial increase in extreme precipitation events in Austin over the coming century, how come there has been no significant trend since 1898, 1970, or 1984?

The study also predicts “a slight increase in the number of dry days [precipitation <0.01”] per year” due to climate change.  That's unusual, too.  There is actually a highly statistically significant trend toward declining – not increasing – numbers of dry days per year in Austin since 1898, and over the past century (i.e., since 1914), there is no correlation whatsoever.

Furthermore, while there has been an uptick in average summer maximum temperatures during the past several years, over the past century there has been no significant trend. Indeed, if we take the period from 1914 to 2008, there is almost a perfect non-correlation (p=0.96, parametric) for Austin's average summer high temperatures over these 95 years.

In other words, there was not even a subtle hint of increasing summer highs in Austin up to 2008, and then the past five summers have been unusually hot.  This type of trend cannot rationally be explained by current anthropogenic climate change theories, and may instead just be a period of a few extremely hot summers, much like Austin saw in the early 1920s.  Time will tell, but these types of patterns over time advocate patience and caution on climate predictions rather than alarmism.

Jumping on a recent hot spell only a few years in length after almost a century of absolutely no change is far too rash for policy-making efforts.  Wait several more years, and see if the recent trend of extremely hot summers continues in Austin, or if summer highs return back down to the historical norms the city was experiencing before 2008.

Thus, when I see predictions like the following, I am deeply skeptical:

At the end of the century, Austin’s average summertime high temperature could be six degrees above today’s average high of 97 degrees. And it may be hotter than 110 degrees in the city more than 20 days a year; even one day that hot is a rarity now.

If there was a consistent and continuous increasing trend in Austin's average summertime high temperatures dating back at least several decades, then perhaps some concern would be warranted at this point.  But not when it is only the past five summers that have been anomalously hot, preceded by a century of no change at all.

Austin has had only two days in recorded history with maximum temperatures above 110 degrees: one in 2000 and one in 2011.  And up to 2008, there was no trend in the highest temperature of the year.  Just the past five years have seen unusually high extreme maximum temperatures.  These types of very recent and very short-term trends mean that more time is needed before making long-term predictions – and certainly before engaging in municipal planning efforts based on what could be just a short blip in the historical record.

This seems like premature climate alarmism in Austin.  The city needs to slow down, get multiple expert opinions on historical trends and climate modeling predictions, and be patient before investing significant public funds in either further detailed studies (especially given the poor predictivity of downscaled climate models) or any policymaking and infrastructure upgrading efforts.  Once again, Texas must avoid the climate shock doctrine.