But an unprecedented three-year experiment conducted at Stanford University is raising questions about that long-held assumption. Writing in the journal Science, researchers concluded that elevated atmospheric CO2 actually reduces plant growth when combined with other likely consequences of climate change namely, higher temperatures, increased precipitation or increased nitrogen deposits in the soil.
The results of the study may prompt researchers and policymakers to re-think one of the standard arguments against taking action to prevent global warming: that natural ecosystems will minimize the problem of fossil fuel emissions by transferring large amounts of carbon in the atmosphere to plants and soils.
"Perhaps we won't get as much help with the carbon problem as we thought we could, and we will need to put more emphasis on both managing vegetation and reducing emissions," said Harold A. Mooney, the Paul S. Achilles Professor of Environmental Biology at Stanford and co-author of the Dec. 6 Science study.
He noted that the Stanford study is the first ecosystem-scale experiment to apply four climate change factors across several generations of plants.
"To understand complex ecological systems, the traditional approach of isolating one factor and looking at that response, then extrapolating to the whole system, is often not correct," Mooney said. "On an ecosystem scale, many interacting factors may be involved."
Jasper Ridge Global Change Project