Saturday, August 20, 2016

The Sixth Extinction by Elizabeth Kolbert

The Sixth Extinction: An Unnatural HistoryThe Sixth Extinction: An Unnatural History by Elizabeth Kolbert
My rating: 4 of 5 stars

While I'm pretty clear on the ongoing sixth extinction and am totally horrified by it, one thing that irked me the whole time was wondering what the other five extinctions were. Though she covered some of the others in the book as well, since nothing was in chronological order, I felt a little confused at the end. So here they are:

1. Cretaceous–Paleogene extinction event. About 75% of all species became extinct. In the seas all the ammonites, plesiosaurs, and mosasaurs disappeared. Kolbert talks at length about the ammonites. All non-avian dinosaurs became extinct during that time. This is the one that was probably caused by a huge asteroid hitting the earth. Kolbert talks about the asteroid idea in an earlier chapter than the ammonite chapter which is confusing.

2. Triassic–Jurassic extinction event (End Triassic): About 70% to 75% of all species became extinct.
It was between the Triassic and Jurassic, but I don't really understand this one, and scientists don't really know what caused it.

3. Permian–Triassic extinction event (End Permian): Earth's largest extinction killed about 96% of all marine species and an estimated 70% of land species, including insects. It's called the "Great Dying" and apparently it ended the primacy of mammal-like reptiles? Not sure what those were? Furry reptiles that took care of their young? Scientists also don't know what caused it, but possibly a climate change event.

4. Late Devonian extinction: A prolonged series of extinctions eliminated about 70% of all species. This extinction event lasted maybe 20 million years, with a series of "extinction pulses." Maybe because of more climate change?

5. Ordovician–Silurian extinction events which occurred 443.8 million years ago. Two events occurred that killed off 60% to 70% of all species. Together they are ranked by many scientists as the second largest of the five major extinctions in Earth's history in terms of percentage of genera that became extinct. Not sure what caused this one either. Possibly a combination of climate changes including some freezing.

6. Holocene- 10,000 BCE — now, not even sure yet how many species have been killed off. Caused by humans. Kolbert discusses the American mastodon, Auk, rainforest frogs, coral, bats worldwide, and some other species.

These extinctions are especially terrifying because we're destroying entire areas, changing the climate, destroying food chains, spreading weird diseases. Attempts to stop the damage have largely failed so far. Even if we manage to survive what we're doing the earth might be a really bad place to live for a long time. So... not exactly beac reading.

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