How does rising atmospheric CO2 affect marine organisms?

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CO2 Enhances Plant Production of Cancer-Fighting Substances
Idso, S.B., Kimball, B.A., Pettit III, G.R., Garner, L.C., Pettit, G.R. and Backhaus, R.A.  2000.  Effects of atmospheric CO2 enrichment on the growth and development of Hymenocallis littoralis (Amaryllidaceae) and the concentrations of several antineoplastic and antiviral constituents of its bulbs.  American Journal of Botany 87: 769-773.

What was done
The authors grew spider lily (Hymenocallis littoralis) plants out-of-doors at Phoenix, Arizona in clear-plastic-wall open-top enclosures that had their atmospheric CO2 concentrations continuously maintained at either 400 or 700 ppm for two consecutive two-year growth cycles.  At the end of each of the two-year periods, the underground bulbs of the plants were harvested and the amounts and concentrations of a number of substances proven to be effective in fighting various human cancers and viral diseases were measured.

What was learned
The 75% increase in the air's CO2 concentration resulted in a 48% increase in aboveground plant biomass and a 56% increase in belowground (bulb) biomass.  In addition, it increased the concentrations of the five bulb constituents possessing the anticancer and antiviral properties.  Mean percentage increases in these concentrations were, in the words of the authors, "6% for a two-constituent (1:1) mixture of 7-deoxynarciclasine and 7-deoxy-trans-dihydronarciclasine, 8% for pancratistatin, 8% for trans-dihydronarciclasine, and 28% for narciclasine, for a mean active-ingredient percentage concentration increase of 12%."  Combined with the 56% increase in bulb biomass, these percentage concentration increases resulted in a mean active-ingredient increase of 75% for the 75% increase in the air's CO2 concentration.

What it means
The substances evaluated in this study have been demonstrated to be effective in fighting a number of human maladies, including leukemia, ovary sarcoma, melanoma, and brain, colon, lung and renal cancers, as well as Japanese encephalitis and yellow, dengue, Punta Tora and Rift Valley fevers.  The finding that atmospheric CO2 enrichment increases both the concentrations and absolute amounts of these substances in the bulbs of the common spider lily plant bodes well for the future production of botanical-based medicines.  It additionally points to the tantalizing possibility that there may be a number of health-promoting substances in other plant tissues, such as common foods, that may also have their concentrations enhanced by the ongoing rise in the air's CO2 concentration.  In fact, the astonishing finding of ever-lengthening life-spans in all of the G7 nations over the past 50 years (see our Journal Review: Why Are We Living Longer?) suggests we may already be benefiting from this phenomenon in a major way.

Reviewed 1 July 2000