OZONE smog will accentuate global warming this century, for it will damage plants and trees that help soak up carbon emissions, a study to be published today said. Its authors fear a major factor in the climate-change equation has been badly overlooked.

While the increasing carbon dioxide level should encourage plant growth, the increasing greenhouse ozone near the earth's surface is countering that effect.

The hole in the ozone layer has returned to its 2001 size as air conditioners using banned chemicals become popular in developing countries