Tree Growth

Stunted by Ozone

Ozone pollution is four times greater now than prior to the Industrial Revolution in the mid-1700s. If modern dependence on fossil fuels continues at the current pace, future ozone concentrations will be at least double current levels by the end of this century with the capacity to further decrease the growth of trees.

The study is the first statistical summary of individual experimental measurements of how ozone will damage the productivity of trees, including data from 263 peer-reviewed scientific publications.

Ozone is the third strongest greenhouse gas, directly contributing to global warming, and is the air pollutant considered to be the most damaging to plants. But more importantly, it has the potential to leave more carbon dioxide, ranked as the strongest greenhouse gas of all, in the atmosphere by decreasing carbon assimilation in trees. Ozone pollution occurs when nitrogen oxides have a photochemical reaction with volatile organic compounds.

"This research quantifies the mean response of trees to ozone pollution measured in terms of total tree biomass, and all component parts such as leaf, root and shoot, lost due to ozone pollution," said Victoria Wittig, lead author of the study. "Looking at how ozone pollution affects trees is important because of the indirect impact on carbon dioxide concentrations in the atmosphere which will further enhance global warming, in addition to ozone's already potent direct impact."