Under a White Sky summary

The Chicago Sanitary and Ship Canal is a murky river that stretches 160 feet wide. Its role is deeply important,⁠ if not glamorous.

Before the canal existed, all of Chicago’s waste was dumped into the Chicago River. From there, the waste –⁠ including human feces, cow and sheep manure, and rotting animal guts –⁠ floated down into Lake Michigan. The lake was, and still is, the city’s only source of drinking water. 

In the mid-1800s, a large species of amphibian called the cane toad was brought to the Caribbean. Cane toads are a splotchy brown color, with bodies weighing up to six pounds and eyes set with thick ridges that give them a permanently leery expression.

The toad’s reason for being in the Caribbean was to fight beetle grubs, a species that was destroying regional sugarcane plants. Eventually, the toads were also brought to Australia, where they quickly spread out and made themselves at home. 

On the edge of blisteringly hot Death Valley, California, is a cavern known as Devils Hole. Swimming in it is a species of deep blue, inch-long fish called pupfish – specifically, Devils Hole pupfish. The name originated from the male pupfish who can sometimes be seen wrestling one another in a way that vaguely resembles puppies at play. 

These tiny fish are also perhaps the rarest fish in the world. They only exist in this unique location. Because of their vulnerable status, biologists make special efforts to ensure that the species can survive. 

The 1980s were a particularly devastating time for Caribbean coral reefs. Thanks to a combination of development, overfishing, and pollution, half of the Caribbean’s coral disappeared during this decade alone. 

The problem, however, wasn’t limited to the Caribbean. Climate change was warming the oceans to temperatures many corals couldn’t tolerate. In 1988, for instance, a major spike in water temperatures spelled death for more than 15 percent of corals worldwide.

For the last ten thousand years or so, Earth has had a pocket of remarkably stable climate. Prior to that, rapid climate changes were the norm rather than the exception. 

But we humans lucked out. The stable climate we entered into allowed us to settle in places permanently, building farms and cities. To do that, we chopped down and burned forests, which released CO2 into the atmosphere. The quantities of CO2 were small but impactful, causing overall atmospheric CO2 levels to remain constant when they should have been falling in accordance with natural cycles.

On the evening of April 5, 1815, loud booms resembling cannon fire began to issue ominously from Indonesia’s Mount Tambora. Five days later, lava and a massive column of smoke erupted from the volcano.

Thousands of people died almost immediately, but Tambora’s killing spree continued for years. When the volcano erupted, it released over a hundred million tons of gas and fine particles into the atmosphere. Those particles blocked the sun, resulting in frigid temperatures that caused harvests to fail and potentially millions of people to starve.