In DepthATMOSPHERIC CHEMISTRY

As polar ozone mends, UV shield closer to equator thins

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Science  09 Feb 2018:
Vol. 359, Issue 6376, pp. 623
DOI: 10.1126/science.359.6376.623

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Summary

Thirty years after nations banded together to phase out chemicals that destroy stratospheric ozone, the gaping hole in Earth's ultraviolet radiation shield above Antarctica is shrinking. But new findings suggest that at midlatitudes, where most people live, the ozone layer in the lower stratosphere is growing more tenuous—for reasons that scientists are struggling to fathom. In an analysis published this week, researchers found that from 1998 to 2016, ozone in the lower stratosphere ebbed by 2.2 Dobson units—a measure of ozone thickness—even as concentrations in the upper stratosphere rose by about 0.8 Dobson units. The culprit may be ozone-eating chemicals such as dichloromethane that break down within 6 months after escaping into the air.

  • * April Reese is a freelance journalist in Santa Fe.