Submitted to: Global Change Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/15/2000
Publication Date: N/A
Interpretive Summary: Researchers have recently reported a marked increase in the percentage and persistence of allergies and asthma among the general population. The epidemiology of allergies depends on both sensitivity to the allergen and environmental factors which influence the amount of allergen present. Although environmental factors such as rainfall are recognized as influencing pollen production, the impact of rising atmospheric carbon dioxide [CO2] on the potential growth and pollen production of hay-fever inducing plants is unknown. Here we present measurements of common ragweed growth and pollen production from pre-industrial carbon dioxide concentrations of 280 ppmv to current concentrations, 370 ppmv, and a projected 21st century concentration 600 ppmv. We find that exposure to current and elevated [CO2] increased ragweed pollen production by 131% and 320%, respectively, for plants grown at pre-industrial levels. The observed stimulations of pollen production from the pre-industrial carbon dioxide concentration were due to an increase in the number (370 ppmv) and number and size of floral spikes (600 ppmv). Our results suggest that the continuing increase in atmospheric carbon dioxide has already and may continue to influence public health by stimulating the potential growth and pollen production of allergy-inducing species such as ragweed.
Technical Abstract: Although the epidemiology of allergies is complex, the impact of rising atmospheric carbon dioxide [CO2] on the potential growth and pollen production of hay-fever plants is unknown. To determine possible changes associated with rising carbon dioxide, common ragweed (Ambrosia artemisiifolia L.) was grown to maturity at three different carbon dioxide concentrations; 280 ppmv (pre-industrial), 370 ppmv (current), and 600 ppm (future, elevated). Exposure to current and elevated [CO2] resulted in a significant increase in relative growth rate (+20%, +26%) and single leaf photosynthesis (+170%, +250%) when compared to plants grown at pre-industrial [CO2]. Pollen production by staminate flowers increased significantly for plants grown at the pre-industrial [CO2] when exposed to current and elevated concentrations of CO2 (+131 and +320%, respectively). The observed increase in pollen production from pre-industrial carbon dioxide concentrations was due to an increase in the number and number and size of floral spikes (current and future [CO2], respectively). Data from the current study suggest that the ongoing rise in atmospheric carbon dioxide has already and will continue to influence public health by stimulating the potential growth and pollen production of allergy-inducing species such as ragweed.