You Don’t Wanna Know How A Climate Change-Induced Mass Extinction Can End (Hint: Lizards)

You Don’t Wanna Know How A Climate Change-Induced Mass Extinction Can End (Hint: Lizards)

It’s a widely accepted fact that we’re screwed. That’s sort of in a general sense. You, reader, are certainly not making it past 2100. And civilisation? Maybe it will meet its maker from superbugs and nuclear war in 50 years, or sea level rise in a few centuries. Maybe it will be an asteroid in a thousand years, or the Sun engulfing the planet in a few billion. Or, maybe a new mass extinction event will result in a lizard-pocalypse, which is basically what happened in Australia 35 million years ago.

Image: Jessi Swick/Flickr

A pair of Australian scientists took a look at species (particularly geckos) living and dying around the Eocene-Oligocene boundary, a time where the Earth cooled rapidly and lots of species went extinct. But one species’ hell is another’s habitat, and survival-of-the fittest meant lots of lizard species who happened to thrive in the desert did quite nicely in the drier climate.

People who study our round planet accept the fact that there were five major mass extinctions. You may have heard of the one 65 million years ago that claimed the dinosaurs. The Eocene-Oligocene extinction event wasn’t as bad, but still cut down lots of family trees, especially in the ocean. Ninety per cent of mollusc species died off the US Gulf Coast, according to one Nature paper. Folks generally consider the event to be the result of rapid global cooling — roughly 5C in less than 100,000 years — from either volcanism or a meteor.

The researchers used an enormous dataset representing 90 per cent of the so-called pygopodoid geckos, including fossils and changes in biological molecules like DNA, RNA and proteins, to build computer models that could analyse the diversity of Australian gecko species going back tens of millions of years. They noticed a decline in species diversity around the Eocene-Oligocene event, which they assumed stemmed from the lizards’ inability to keep up with the cooling and changing environment and other geologic factors. But then, new species of geckos started to flourish in the resulting dry environment (especially 20 to 10 million years ago), taking up residence throughout the continent. The researchers published their analysis in the journal Evolution two weeks ago.

Now, there are a lot of caveats to any study that tries to analyse communities of species from that long ago. The study involved lots of mathematical modelling — the researchers don’t have a fossil go alongside every branching point in the evolutionary tree where they think a new species emerged, Richard Hulbert, Vertebrate Paleontology Collections Manager at the Florida Museum of Natural History, told Gizmodo. “A major assumption of this whole study they can take these points of branching and accurately put them into geologic time on a numeric scale,” he said.

Also, all of this stuff is happening on million year timescales. If you remember what I said earlier, you will be dead by 2100, and wouldn’t notice this level of species change during your lifetime. And the scientists are just studying a history of gecko species in Australia, so we can’t extrapolate that much about, say, what’s going to happen to giraffes in Africa. (Although we have other hints that giraffes, along with many animals, are headed toward extinction today thanks to human activity.)

But still, the study shows that while many species go extinct, some have thrived in the past thanks to a rapidly-changing climate.

“Studies like this and also studies using actual fossils allow us to make such predictions about potentially what can happen during intervals of climate change,” said Hulbert.

So, who knows, maybe the future will be full of lizards. But like I always say, whatever. Nothing matters. Chaos reigns.