The Sixth Extinction: An Unnatural History

by Elizabeth Kolbert

the concentration of carbon dioxide in the air has risen by forty percent over the last two centuries, while the concentration of methane, an even more potent greenhouse gas, has more than doubled.

the concentration of carbon dioxide in the air today—a little over four hundred parts per million—is higher than at any other point in the last eight hundred thousand years.

Triassic, for example, can now be found towering thousands of feet above sea level in the Austrian Alps. The Guadalupe Mountains in west Texas are what’s left of reefs from the Permian period that were elevated in an episode of “tectonic compression” about eighty million years ago. Reefs from the Silurian period can be seen in northern Greenland.

between 22 and 31 percent of the species would be “committed to extinction” by 2050.

A, T, G, and C, so that a stretch of the human genome might be represented as ACCTCCTCTAATGTCA. (This is an actual sequence, from chromosome 10; the comparable sequence in an elephant is ACCTCCCCTAATGTCA.) The human genome is three billion bases

Paul Ehrlich: IN PUSHING OTHER SPECIES TO EXTINCTION, HUMANITY IS BUSY SAWING OFF THE LIMB ON WHICH IT PERCHES.