Climate scientists are leaving few stones unturned as they look for ways to offset global warming, including geoengineering–the deliberate modification of the environment on a large scale. One widely discussed geoengineering idea for cooling the planet has recently been judged to have some potentially harmful side effects.  

The idea was to regularly inject large amounts of sun-blocking sulfate particles into the stratosphere. The goal would be to cool earth’s surface, much as sulfur particles from major volcanic eruptions in the past have resulted in reduced surface temperatures.

Simone Tilmes of the National Center for Atmospheric Research and a team of researchers looked at the potential impact on ozone over the poles. They found that artificial injections of sulfates would destroy much of the ozone layer about the Arctic and would also delay the expected recovery of the ozone hole over the Antarctic by about 30 to 70 years.

To determine the relationship between sulfates and ozone loss, the researchers used a combination of measurements and computer simulations. They then estimated future ozone loss by looking at two geoengineering schemes–one that would use volcanic-sized sulfates and a second that would use much smaller injections.

Tilmes and others caution that the actual impacts on ozone could be somewhat different than estimated if atmospheric changes led to unusually warm or cold polar winters. They also warn that a geoengineering project could lead to even more severe ozone loss if a major volcanic eruption took place at the same time.