Sunday, May 17, 2009

Legal Scholarship, Global Warming, and Jazzfest

I've been thinking about this for a few years, ever since I read Can We Save New Orleans?, 19 Tul. Envtl L. Rev 1 (2006), by Professor Oliver Houck of Tulane School of Law. It's a very good, informal riff on a lot of the environmental issues related to New Orleans, Louisiana, the Mississippi River, all tied up in a nice bow of justifiable post-Katrina anger and personal narrative, including excerpts from Professor Houck's own evacuation journal.

What stood out in my mind from this article when I first read it was a rather specific prediction about global warming, though I slightly mis-remembered it - he doesn't give a time frame like I had thought he had (a lot of anthropogenic global warming alarmists tend to omit specific predictions of when the planet is going to be significantly hotter than whenever their spreading their current hysteria). But Professor Houck does give a specific temperature prediction linked to one of our big annual cultural events here in New Orleans:
Here in Louisiana we will be warmer in summer (think, maybe, 103 degrees at Jazz Fest) .... Houck, Tul. Envtl. L. Rev 1, at 27.
For one, the "maybe" in the parenthetical is his big weasel-word out of pulling the specific figure of 103 degrees out of thin air. The rest of his sentence discusses predicted drier conditions and the effect that may have on our state's leading crops and then a footnote for that sentence refers to (after an "id." or two) this:
Envtl. Prot. Agency, Climate Change and Louisiana 3 (1997) available at http://$File/la_ impct.pdf
The only part of that four-page report that I found which predicted specific temperature change in Louisiana was this:
[It] is projected that by 2100, temperatures in Louisiana could increase about 3°F (with a range of 1-5°F) in spring and summer, slightly less in winter, and slightly more in fall. Envtl. Prot. Agency, Climate Change and Louisiana 2 (1997).
Like a lot of the source material cited by alarmists, it's a bit more measured than the attention-grabbing headlines and statements: "could increase" anywhere from one to five degrees in a hundred years. But 103 degrees at Jazz Fest? Yes, Jazz Fest is hot: it's a music festival with tens of thousand of people crowded onto a dirt and asphalt racetrack and fairgrounds in late spring. Is it really likely to be 103 degrees there any time soon? Ever?

As a librarian I deal in facts. Students sometimes think we know how to find anything, but I tell them that while that's not true, I do know how to find out how to find just about anything. So I spent some time learning about weather data the did some research and came up with the average high temperature for Jazz Fest during its 40 year history.

Jazz Fest has had different schedules over its forty year history, so to have a consistent year-to-year set of data, I used a constant set of ten days over the last weekend of April through the first weekend of may - the first Friday through the next weekend's Sunday, which has been the more-or-less consistent schedule for the Fest in the past 15 years or so. Also, I included the days between weekends because the second weekend of Jazz Fest has started to include that Thursday so this way I'm taking an average of the more-or-less same ten days year to year (and because your hardcore Jazz Fest fans make good use of these weekdays to continue enjoying the local music scene, some consider Jazz Fest to be the entire ten day period).

The National Climatic Data Center, part of NOAA, has its primary on-line climate data search here:

It took me a while to figure it out - you submit your query and they actually e-mail you a link a little while later with the information you requested (the link lasts two weeks, but I saved the important data). The various data stations collect different data, and the range of years for which they collected data varies, and the stations nearest the fair grounds don't have complete data for these forty years so I used the main station at the New Orleans airport (which, I think, is the main station in this area - it definitely has the most complete data).

There's no way I could find to get just the data for certain dates, or just the April and May data, for all forty years, so I submitted a request for all forty years of data and then copied the daily high temperatures to my spreadsheet for each year's ten day Jazz Fest "period". (You can view either the original data from the NCDC (PDF) or my spreadsheet of the daily highs (also PDF)).

What I found out is this: the hottest Jazz Fest ever was 2002, when the average temperature was 89.1 degrees. The hottest single day ever was May 2 of that year, when the temperature was 92 degrees. So even if the upper range of the EPA's 1979 prediction is correct, Jazz Fest might be 97 degrees in a hundred years. Still damn hot, but well short of 103 degrees.

Looking over the numbers, its clear there is no definitive warming trend; the second hottest Jazz Fest was 1987, when the average temperature was 84.9 degrees. This year was the tenth hottest (84.9 degrees), but the eleventh, thirteenth, and fourteenth hottest Jazz Fests were all in the 1970s: 1975, 1971, and 1978 - 83.5, 83.4, and 83.1 degrees, respectively. AND the third, fifth, and ninth coolest Jazz Fests were all in the last four years: 2005, 2004, and 2009 - 77.3, 77.7, and 79.1 degrees, respectively.

The full numbers are sorted different ways in the next three charts. Here's the average high temperatures for all forty years, in chronological order (click any of these charts to see larger versions):

And, because there's no shortage of fun things you can do while number crunching, here's the forty years of Jazz Fest ranked from hottest to "coolest" (74.9 degrees is "cool" here in New Orleans):

and here it is the data, coolest to hottest:

Conclusions? Yes, the planet has gotten warmer in the past century or so. But these Jazz Fest temperatures are consistent with a more realistic view of climate change than the anthropogenic alarmists have: there hasn't been a clear "hockey stick" temperature increase in the past few decades and its likely that what warming we have seen peaked in the late 1990s and that natural variations dwarf mankind's contributions to warming the planet.

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