Rising atmospheric carbon dioxide and plant biology: the overlooked paradigm.

As human populations continue to expand, concurrent increases in energy and food will be required. Consequently, fossil-fuel burning and deforestation will continue to be human-derived sources of atmospheric carbon dioxide (CO2). The current annual rate of CO2 increase ( 0.5%) from these sources is expected to continue with concentrations exceeding 600 parts per million (ppm) by the end of the current century (Schimel, et al. 1996). Because carbon dioxide absorbs heat leaving the earth’s atmosphere, there is widespread agreement that increasing CO2 will result in increasing global temperatures. The extent to which temperatures increase, and the potential biological consequences—from sea-level rise, to the spread of malaria—have been discussed and debated extensively in both the scientific and popular literature. Unfortunately, given the focus on global warming, it is seldom acknowledged that no matter what the end effect of rising temperatures, the ongoing increase in atmospheric carbon dioxide, of and by itself, has affected, and will continue to affect, all life on the planet.