Global warming baking lizards

In today's e-mail from TheScientist.com is an article estimating that 20% of lizard species are likely to go extinct because of global warming.

The worst-case scenario of the consequences of global warming - mass extinctions - appears to be a reality for lizards, according to a new report in Science.
The authors found that 12 percent of local populations of lizards have already disappeared from hundreds of sites in Mexico. Furthermore, within the next 70 years, the authors predict that 1 in 5 lizard species will no longer exist anywhere on the planet, all the result of rising global temperatures.

Sounds bad.  How'd they come up with those numbers?

The study began when the authors returned to 200 sites in Mexico that were home to 48 species of Sceloporus lizards, which had already been sampled in 1975 and 1999. They saw that 12 percent of lizards in the Mexican study area were already locally extinct -- meaning, environmental stressors had eliminated the populations in these particular areas.
....
Lizards regulate their body heat by basking in the sun; too hot, and they retreat to shade. Too much time in the shade, however, and they become unable to gather enough food to grow and survive.
The close to 30 co-authors compared the rate of change in lizard populations since the 1970s to historic changes in temperature, and, along with an understanding of lizard physiology and geographic distribution, developed a model to predict how many species would go extinct worldwide, based on how global temperatures are predicted to rise through 2080. The authors then confirmed the model's predictions by comparing them to actual extinction data.

So what the authors did was compare geographical ranges with the change in temperature over time, and the data seem to fit the model they came up with.

I don't know how much attention they paid to possible other factors.  The dependence on temperature seems plausible, and I'm inclined to buy it, but there may be other factors that are being ignored.

The article also states:

"I think the paper is really impressive. It uses historical records of climate variation and population distributions to develop a predictive model. Importantly, it takes past climate variation at face value, without trying to link it to anthropocentric causation," said Henry John-Adler, an ecologist at Rutgers University, who did not participate in the research.

So this change seems to be happening without regard for the amount of temperature change that results from human activity. 

This looks like a measurement of the sensitivity of the lizard species studied to temperature changes in general. Since a great deal of warming seems to have happened in the first half of the 20th Century, I'm wondering if we can conclude that these lizards were even more abundant back then. I'm also inclined to wonder how they managed to weather temperature changes even further in the past.

It may be that we're seeing lizard species that evolved to become too specialized in their requirements, and are being pruned by natural selection.  In this case, we'll see a die-off of the most sensitive and most specialized species, and more adaptable species will survive.   How big is this sensitive fringe?  Well, I guess we can say it's larger than 12%, and it might even be as high as 20%.

And we still don't know how much of this we can prevent, or at what cost.