It is a sobering journey, one that warns of catastrophic surprises that may be in store. So let us take a trip back into deep time, a journey that will begin with the familiar climate of recorded history and end in the feverish, high-CO 2 greenhouse of the early age of mammals, 50 million years ago. To truly appreciate the coming changes to our planet, we need to plumb the history of climate change. This is the grim lesson of paleoclimatology: The planet seems to respond far more aggressively to small provocations than it’s been projected to by many of our models. The transition will be punishing in the near term and the long term, and when it’s over, Earth will look far different from the one that nursed humanity. If CO 2 stays at its current levels, much less steadily increases, it will take centuries-even millennia-for the planet to fully find its new footing. Why? The planet today is not yet in equilibrium with the warped atmosphere that industrial civilization has so recently created. When there’s been as much carbon dioxide in the air as there already is today-not to mention how much there’s likely to be in 50 or 100 years-the world has been much, much warmer, with seas 70 feet higher than they are today. But humanity’s ongoing chemistry experiment on our planet could push the climate well beyond those slim historical parameters, into a state it hasn’t seen in tens of millions of years, a world for which Homo sapiens did not evolve. We have been shielded from the climate’s violence by our short civilizational memory, and our remarkably good fortune. All of recorded human history-at only a few thousand years, a mere eyeblink in geologic time-has played out in perhaps the most stable climate window of the past 650,000 years. “The climate system is an angry beast,” the late Columbia climate scientist Wally Broecker was fond of saying, “and we are poking it with sticks.” When hucksters tell you that the climate is always changing, they’re right, but that’s not the good news they think it is. And humans are injecting more CO 2 into the atmosphere at one of the fastest rates ever. Today, atmospheric CO 2 sits at 410 parts per million, a higher level than at any point in more than 3 million years.
And sometimes, when the planet has issued a truly titanic slug of CO 2 into the atmosphere, things have gone horribly wrong.
During the entire half-billion-year Phanerozoic eon of animal life, CO 2 has been the primary driver of the Earth’s climate. The sea level, meanwhile, has tried to keep up-rising and falling over the ages, with coastlines racing out across the continental shelf, only to be drawn back in again. At others, lots of CO 2 has been hidden away in the rocks and in the ocean’s depths, and the planet has gotten cold. At some points in the Earth’s history, lots of CO 2 has vented from the crust and leaped from the seas, and the planet has gotten warm. And not just based on mathematical models: The planet has run many experiments with different levels of atmospheric CO 2. Since about the time of the American Civil War, CO 2’s crucial role in warming the planet has been well understood. That negligible wisp of the air is carbon dioxide. Of more immediate interest today, a variation in the composition of the Earth’s atmosphere of as little as 0.1 percent has meant the difference between sweltering Arctic rainforests and a half mile of ice atop Boston. When the unseen tug of celestial bodies points Earth toward a new North Star, for instance, the shift in sunlight can dry up the Sahara, or fill it with hippopotamuses. Big rocks whiz by overhead, and here on the Earth’s surface, whole continents crash together, rip apart, and occasionally turn inside out, killing nearly everything. We live on a wild planet, a wobbly, erupting, ocean-sloshed orb that careens around a giant thermonuclear explosion in the void. This article was published online on February 3, 2021. In his photo illustrations throughout this article, the colors of the original photos have been adjusted, but the images are otherwise unaltered. Images above: Glaciers from the Vatnajökull ice cap, in Icelandīrendan Pattengale is a photographer who explores how color can convey emotions in an image.
Photo Illustrations by Brendan Pattengale | Maps by La Tigre