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CO2- and Climate-Induced Effects on Terrestrial Plant Production
Friend, A.D. 2010. Terrestrial plant production and climate change. Journal of Experimental Botany 61: 1293-1309.

What was done
Working with the Hybrid6.5 model of terrestrial primary production, which "simulates the carbon, nitrogen, phosphorus, water, and energy fluxes and structural changes in terrestrial ecosystems at hourly to decadal timescales, and at spatial scales ranging from the individual plant to the whole earth," while employing "the climate change anomalies predicted by the GISS-AOM GCM under the A1B emissions scenario for the 2090s [relative] to observed modern climate, and with atmospheric CO2 increased from 375.7 ppm to 720 ppm" -- a 92% increase -- the author calculated the percentage changes in terrestrial plant production that would occur throughout the world in response to (1) the projected climate changes alone, and (2) the projected concurrent changes in climate and atmospheric CO2 concentration.

What was learned
In response to projected climate changes between 2001-2010 and 2091-2100, net primary production (NPP) of the planet as a whole was reduced by 2.5%, with the largest negative impacts occurring over southern Africa, central Australia, northern Mexico, and the Mediterranean region, where reductions of over 20% were common. At the other extreme, climatic impacts were modestly positive throughout most of the world's boreal forests, as might have been expected when these colder regions received an influx of welcome heat. When both climate and atmospheric CO2 concentration were changed concurrently, however, the story was vastly different, with a mean increase in global NPP of 37.3%, driven by mean increases of 43.9-52.9% among C3 plants and 5.9% among C4 species. And in this case of concurrent increases in the globe's air temperature and CO2 concentration, the largest increases occurred in tropical rainforests and C3 grass and croplands.

What it means
Even for the outlandish magnitude of global warming that is predicted to occur over the remainder of the 21st century, the projected decline in global NPP is rather small; and with the concomitant biological benefits of the aerial fertilization effect of atmospheric CO2 enrichment, along with its ability to greatly increase plant water use efficiency, the worlds of nature and agriculture are projected to come through with flying colors. Fortunately, this response is precisely what we are going to need to be able to provide the extra food that will be required to support the extra billions of people who will be added to the planet between now and the end of the century (see Food in our Subject Index); and to fight against the phenomenon (anthropogenic CO2 emissions), which can make it all possible, is idiocy in the extreme.

Reviewed 30 June 2010