Our Fragile Moment
Michael Mann
PublicAffairs, $30
Over four millennia ago, in the final days of the Akkadian Empire in Mesopotamia, a drought swept over the region, afflicting lands as far away as Greece and what’s now Pakistan. Probably driven by the eruption of a distant volcano, the drying climate devastated local agriculture. A contemporary text, The Curse of Akkad, noted that “the large arable tracts yielded no grain … the irrigated orchards yielded no syrup or wine, thick clouds did not rain.”
As once-prosperous farmlands collapsed in the northern part of the empire, people fled to the south. The southern Akkadians’ response? Build a more than 150-kilometer-long wall between the Tigris and Euphrates rivers, barring entry to any migrants. Soon after, history’s first empire crumbled, dying of thirst in the cradle of civilization.
Climate systems and civilizations are stable only up to a point. In Our Fragile Moment, climate scientist Michael Mann reminds us that today we are pushing the limits of both.
In the book, Mann looks back at episodes of global climate change over the last 4.5 billion years, from eras of deadly heat to wastelands of widespread ice. With each instance, he draws out lessons about what happens to Earth in periods of changing climate. Sometimes, the result is dramatic mass extinctions or geologic upheavals (SN: 8/28/15). Other times, as with the Akkadians, it’s societal collapse.
Earth’s climate system includes regulating forces that tend to buffer against small shifts in climate; ice caps and low clouds reflect sunlight and help cool the planet, for instance. But pushed too far, regulating forces can be overwhelmed, causing the climate to spiral out of control.
This was the case 55 million years ago. As a steady set of volcanic eruptions spewed carbon dioxide into the air, Earth warmed. The heat may have contributed to thinner and less reflective clouds. This in turn would have made the planet even…
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