Trends in Ozone Loss and Increased UV Radiation


The 1995 Nobel Prize recognized the scientists who first sounded the alarm about ozone loss in the stratosphere. Ozone in the upper atmosphere acts as a sunscreen, shielding us from harmful ultraviolet sunlight. Decreasing ozone means increasing UV and increasing damage to organisms exposed to sunlight. However measuring the ozone in the stratosphere is rather like trying to measure the average temperature of the planet against the background of seasonal changes, weather, and El Niños. Many years' worth of careful measurements are required to observe gradual changes in both global temperature and global stratospheric ozone. A recent Science paper reports that twenty years' worth of data shows clear evidence of ozone decreases in the stratosphere1. The trend should reverse in the next ten to twenty years and then ozone is expected to recover.

In a related paper, scientists in New Zealand have made a long time series of observations of how much harmful UV is reaching the surface of the Earth. In the summer of 1998-99 sunburning UV was 12 percent higher than it was earlier in the decade. These are the first results that directly link ozone loss with an increase in sunburning UV radiation.

We spoke with William Randel about his work on stratospheric ozone measurements and also about McKenzie's paper on increased UV.

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