The Anthropocene - Christian Schwägerl

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For continual measured data, see http://www.esrl.noaa.gov/gmd/ccgg/trends/.

      FOUR Signals of Earth Time

      AS YOU READ THESE LINES, various time scales are at work. It takes just milliseconds for your brain to interpret these letters by means of synapses and neurons, and mere seconds for you to put what I am writing into context. It has taken months, years and even decades for your brain to mature to its current state. Your brain has a history going back hundreds of thousands or even millions of years. The molecules in your brain that perform these feats are billions of years old.

      Thanks to the work of brain researchers, molecular biologists, evolutionary scientists and geologists, we have become familiar with the different time scales in which our lives exist—from the femtoseconds of the quantum world to billions of years of cosmic history.

      Contemporary science makes it astonishingly easy to go on a mental time journey, taking enormous leaps through long periods. But it wasn’t that long ago that the intellectual elites of Europe or America had a completely repressed relationship with such timeframes. A mere two to three hundred years ago it was considered heretical, and a sure path to damnation, to believe that the earth was any older than 6,000 years. The French natural scientist Georges-Louis Leclerc (later Comte de Buffon), was one of the first, in the late 18th century, who dared question the timeframe that church officials had deduced from the Old Testament. By examining the rate at which molten iron cooled, Buffon put forward the hypothesis that the earth, with an inner core of iron, had to be about 75,000 years old.85 Even this overly conservative calculation got Buffon into trouble with his university and with the Catholic Church. To this day, creationists, mostly in the United States, use absurd claims to try to prove that the earth is only a few thousand years old.86

      Time has been understood differently in non-Western cultures, which have been more open to the idea of a deep past. In the Hindu religion a single day and night in the life of the creator god Brahma lasts 8.64 billion years and a year, for Brahma, lasts 3.11 trillion years. The Buddha described how an enormous mountain could be worn away by rubbing it with a silk scarf before one world cycle, or Maha-Kalpa, had passed.

      In Western societies, it has taken much longer than in the East to comprehend the temporal dimensions of existence. When, in the nineteenth century, scientists began to measure the age of rocks and chemical compounds using sophisticated instruments, an amazing expansion of time began, from the theologians’ notion of a 6,000 year existence to the realization that the earth may actually be 4.57 billion years old.

      What were humans to do with this extended past? Awestruck by the magnitude of time’s expansion, a group of natural scientists formed an exclusive assembly of “terrestrial timekeepers,” holding the first International Geological Congress in Paris in 1878. Since the foundation of the International Union of Geological Sciences (IUGS), the self-appointed task of its members has been to divide the past into logical intervals and give names to the various epochs. The chief concern was to tell the “longest story” but in reverse—the story of the earth itself—dividing it into compelling chapters. Scientists who do this are called stratigraphers, after the strata or rock layers that lie beneath us. They spend their professional lives at locations where strata have broken up and become visible on the surface, or where core drilling has revealed earth’s crust as a multi-layered cake of various colors, thicknesses and compositions. They use complex machinery to determine the age of the stones and minerals they find and generally, the deeper the strata, the older they are.

      The largest and most important constituent scientific body in the IUGS organization of terrestrial timekeepers is the International Commission on Stratigraphy. In its numerous task groups and committees, scientists discuss which “signals” in the rock layers justify separating (and naming) one sub-plot of earth’s history as distinguished from another. This is done in a most precise, scientific manner in order to create a reliable classification and avoid having to alter the boundaries of these epochs every few years. Only in the naming is some degree of freedom and creativity

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