How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic

Pollen Production by Ragweed in a Doubled-CO2 Atmosphere
Wayne, P., Foster, S., Connolly, J., Bazzaz, F. and Epstein, P.  2002.  Production of allergenic pollen by ragweed (Ambrosia artemisiifolia L.) is increased in CO2-enriched atmospheres.  Annals of Allergy, Asthma, and Immunology 88: 279-282.

What was done
The authors grew common ragweed plants (Ambrosia artemisiifolia L.) - which are found along roadsides and in disturbed habitats throughout much of the United States and Canada - from seed in controlled-environment glasshouses maintained at ambient (350 ppm) and enriched (700 ppm) atmospheric CO2 concentrations for 84 days, at which time they carefully sampled the pollen from the central plants of each stand, assessed its characteristics, and then harvested all mature seeds and above-ground shoot material.

What was learned
In the words of the authors, "stand-level pollen production was 61% higher in elevated versus ambient CO2 environments."  Also, the "CO2-induced growth stimulation of stand shoot biomass was similar to that of total pollen production."  That these results are robust is suggest by the fact that they parallel those reported previously by Ziska and Caulfield (2000).

What it means
The authors say "it will be challenging to accurately predict the future threat to public health caused by CO2-stimulated pollen production," since "it is likely that plant pollen production will also be influenced by factors expected to change in concert with CO2, including temperature, precipitation, and atmospheric pollutants."  Nevertheless, they say their research results suggest "the incidence of hay fever and related respiratory diseases may increase in the future."  Although such a consequence is possible, it is by no means certain; and if it does materialize, we suggest in our Editorial of 10 April 2002 that it will be but a small price to pay for the concomitant positive effects of atmospheric CO2 enrichment on agricultural productivity, which will be needed to avoid the starvation of massive segments of the planet's human population but a few short decades from now.

Ziska, L. and Caulfield, F.  2000.  The potential influence of rising atmospheric carbon dioxide (CO2) on public health: pollen production of the common ragweed as a test case.  World Resource Review 12: 449-457.

Reviewed 24 April 2002