Air Quality-Global Climate Change-Forest Productivity: A Frame of Reference, 1990 Environmental Conference Proceedings
The evidence for a significant impact of sulfur and nitrogen in the form of acid rain on forests in the United States is minimal at ambient levels of deposition. Ozone at ambient levels has been shown in some experiments with some species/genotypes of trees to affect rate of growth. Global climate change is postulated by many based on increases in "greenhouse" gases, principally carbon dioxide, in the atmosphere. At present there is no clear signal of change during the last century: climate has changed in the past, e. g., the Pleistocene.
Using first principles of biology and mathematics a model is developed to assist the reader in posing critical questions. The critical questions about environmental changes usually involve the rate of change of the factors inducing the change. In the final analysis, the answers are judgment calls.