Naafs’ team studied examples of lower-quality coals called lignites, or fossilized peat. The Powder River Basin in the United States, for instance, is filled with fossil Paleocene swamplands that, when burned today, contribute about 10 percent of U.S. To study Earth’s past, scientists need good rocks to study, and fortunately for geologists and fossil-fuel companies alike, the jungles and swamps of this early age of mammals left behind lots of coal. And the temperatures they unearthed are unsurprisingly scorching. Last week, Naafs and colleagues released a study in Nature Geoscience that reconstructs temperatures on land during this ancient high-CO 2 hothouse of the late Paleocene and early Eocene epochs-the sweltering launch to the age of mammals. Based on our research of these ancient climates, though, it’s probably more than we thought.” “But exactly how much it will warm by the end of the century, we don’t know. “You put more CO 2 in the atmosphere and you get more warming, that’s just super-simple physics that we figured out in the 19th century,” says David Naafs, an organic geochemist at the University of Bristol. If this number sounds familiar, 1,000 ppm of CO 2 is around what humanity is on pace to reach by the end of this century. This is what you get in an ancient atmosphere with around 1,000 parts per million (ppm) of carbon dioxide. There were perhaps even sprawling, febrile dead zones spanning the tropics, too hot even for animal or plant life of any sort. On the other side of the blue-green orb, in waters that today would surround Antarctica, sea-surface temperatures might have topped an unthinkable 86 degrees Fahrenheit, with near-tropical forests on Antarctica itself. The first lemur-like primates leapt from the treetops, and hoofed things of all varieties dashed through the forest.īut the most striking feature of this early age of mammals is that it was almost unbelievably hot, so hot that around 50 million years ago there were crocodiles, palm trees, and sand tiger sharks in the Arctic Circle. Early whales pranced across a Pakistani archipelago on all fours, testing out life in the water. Within a few million years, loosed from under the iron heel of the vanished giants, they began to experiment. Before long, life settled into new rhythms: Earth hosted 50-foot-long boas sliding through steam-bath jungles, birds grew gigantic in imitation of their dearly departed cousins, and mildly modern mammals we might squint to recognize appeared. In the wake of Armageddon our shell-shocked ancestors meekly negotiated new roles on a planet they inherited quite by accident. Earth’s newest crater was still a smoldering system of hydrothermal vents, roiling under the Gulf of Mexico. The planet was still hungover from the astonishing disappearance of its marquee superstars, the dinosaurs.
They were strange days at the beginning of the age of mammals.
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