Pros and cons of radioactive dating

MAINZ, Germany -- The man who named the Anthropocene has had a change of heart.

Twelve years ago, Paul Crutzen, a Nobel laureate and atmospheric chemist, coined the term "Anthropocene" as shorthand, an argument wrapped in a word.

Known for his Nobel-winning work on the ozone hole, Crutzen famously blurted out his new geological epoch at a meeting of the International Geosphere-Biosphere Programme (IGBP) near Mexico City in 2000, after a paleoclimate scientist invoked the Holocene 10 times or so.

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It made the cover of But while the Anthropocene fad may wane, the judgment of stratigraphers will bear the test of time.

If the International Commission on Stratigraphy, the bureaucracy that rules on issues of geological time, decides that the world has entered an epoch dominated by man, the verdict will reverberate with a clamor matched by few academic findings. Zalasiewicz's working group has embarked on an exhaustive search to find the uniform signals that will remain embedded in the Earth for millions of years, after much of our world erodes.

On further thought, Crutzen's start date may have been off, he said during a visit to the gleaming new building of the Max Planck Institute for Chemistry, nestled just west of downtown Mainz, the city famous as Gutenberg's home.

The institute's elder statesman, Crutzen speaks with a frail voice and resembles a wise gnome.

"All of these discussions about any unit in geology take an age, almost literally," he said.

By nature, stratigraphy is a conservative profession, resisting proposals even from its own eminences, let alone offhand remarks from climate scientists.It's not that stratigraphers want to fight a rear-guard action against the realities of human influence on the planet, added Whitney Autin, a geologist at the State University of New York, Brockport, who has criticized the Anthropocene's stratigraphic credentials. "When you bring it down to the nuances of how we practice our science, the requirements go up." Before there was the Anthropocene, there was the "Coca-Cola layer." Geologists have long joked about the traces left behind a million years in the future if humanity wiped itself out. The late Derek Ager once said that to study the stratigraphy of Alaska in the future, beer bottle caps could be an excellent guide.It's great that it's raising environmental awareness, he said. But beyond a few intellectual misfits of the 19th and 20th centuries, most geologists demurred from formalizing their after-dinner chatter.Notoriously, the field wrangled for 60 years over the Quaternary, the geological period that enwraps the Holocene.Debates about the boundaries often turn political and bitter, and last forever, said Michael Ellis, head of climate change science at the British Geological Survey."Whenever you go somewhere in the world and make measurements, you cannot avoid having to deal with humankind," Crutzen said.

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