Nobel-winning scientist Paul Crutzen dies at 87

Paul Crutzen, the Dutch atmospheric chemist whose work helped save the ozone layer and who later popularized the idea of the "Anthropocene," died on Thursday.

The big picture: Crutzen's research was key to identifying the role that human-made chlorofluorocarbons (CFCs) played in destroying the ozone layer. But his truly lasting legacy may be his early recognition that human beings had so altered the world that we had entered a new geological epoch: the Anthropocene.

Background: Crutzen, who died at 87 after a long illness, shared the Nobel Prize for Chemistry in 1995 for his work predicting the development and mechanics of the ozone hole.

• Crutzen, along with Mario Molina and Sherwood Rowland, showed that continued use of CFCs — chemicals used in aerosol sprays and refrigerants — would lead to greater levels of ozone depletion, which in turn would damage human health and the environment.
• Their work laid the groundwork for the passage of the Montreal Protocol in 1987, an international treaty that phased out ozone-depleting substances and quite literally helped save the world.

Details: Later in his career, Crutzen began looking to the enormous impact human activities were having on the planet — so enormous, in fact, that it represented an utter break in the Earth's 4.5 billion-year history.

• In a 2002 Nature article, Crutzen coined a name for that new epoch: "the Anthropocene."
• As Crutzen co-wrote in an article nine years later: "We humans are becoming the dominant force for change on Earth."
• It makes sense, then, that Crutzen later moved onto studying solar geoengineering that could artificially cool the climate if global warming ran out of control, an action that if undertaken would represent perhaps the ultimate expression of the Anthropocene.

The bottom line: Crutzen's legacy is a healing ozone layer, and a clearer vision of the world we've made.

Editor's note: This post has been corrected to state that Sherwood Rowland won the Nobel Prize with Crutzen (not Stewart Rowland).