John Nielsen-Gammon, our Texas State climatologist came up with this scary image that most of you have seen, and that everyone in Texas ought to take a good long look at. I was one of the first to reproduce it, but I’ve seen in lots of places since, and with good reason.
Unfortunately, John has followed up on this contribution with what I consider a mistaken article, wherein he claims that
“Texas would probably have broken the all-time record for summer temperatures this year even without global warming.”
Before we get into his argument and its drawbacks, let’s note the obvious. We see that this years drought/heatwave is far outside the observed pattern distribution of events.
So is it a “New Normal”? Is Texas in perpetual drought now? Will we swing back and forth out of unheard-of droughts and unheard-of floods? Will Australia do the same, along with other parts of the formerly semi-arid subtropics? Certainly this is the intuitive impression that many of us come away with. Barry Brooks is no amateur, and he was at least willing to quote a colleague saying
“Given that this was the hottest day on record on top of the driest start to a year on record on top of the longest driest drought on record on top of the hottest drought on record the implications are clear…
It is clear to me that climate change is now becoming such a strong contributor to these hitherto unimaginable events that the language starts to change from one of “climate change increased the chances of an event” to “without climate change this event could not have occured”.
Clearly, we can say similar things in Texas this year. But should we? Nielsen-Gammon says we shouldn’t.
Let me summarize his argument:
- The temperature anomaly this summer is about 5.4 F
- Global warming to date has led to a local warming of Texas summertime temperatures of 0.5 F, so the temperature anomaly can be divided into 0.5 F background warming + 4.9 F other warming.
- There is a strong correlation between annual rainfall variation and annual temperature in the graph. N-G finds a second order curve that fits the data [
about as well as the linear fit] (see comments), and figures that the low rainfall could account for most of the remaining 4.9 F
- He sinks into the tea-leaf territory of the “AMO” and claims to pick up the balance
- Leaving aside the odd idea of superposition of temperature anomalies and the very weak evidence for the AMO, clearly there is a plausible claim that the huge temperature anomaly is “mostly” “because of” the drought
- There is no obvious trend in Texas toward drought, so climate change does not cause unheard-of droughts
- Therefore this is a fluke and has nothing to do with climate, or that other fluke in Australia in ’09, or all the other flukes we have been seeing lately
There is a small, isolated urban country where the wild fauna have been eliminated, and the public is only familiar with pets: dogs, cats, hamsters, and a few horses used in ceremonial events. The entire population knows very little about other animals, and even the experts have acrimonious debates based on fossil records and old paintings, just as we are familiar with contemporary climate but have to extrapolate to ancient or future climates.
- There’s a first time for everything.
- If you push something hard enough it will fall over.
Update: Via Google Plus, Jonathan Abbey summarizes my argument nicely:
Climate characterizes the statistics of weather and the statistical bounds of weather. If we start seeing weather patterns change, that can indicate a change in climate.
The question is all about how likely it is that this weather would occur if the statistical parameters of the climate were held fixed as it has been since instrumental records began, say.
If weather like this is sufficiently unlikely under our previous understanding of regional climate, it may be (a piece of) evidence that the climate is itself experiencing a dislocation.
Which is sort of interesting.