The Role of Roots
At Elevated CO2 Concentrations, Plants Have More Extensive Root Systems
One of the reasons why plants are able to positively respond to atmospheric CO2 enrichment when resource limitations such as water or nitrogen significantly curtail their growth is that plants grown at elevated CO2 concentrations typically have more extensive and active root systems, which allow them to more thoroughly explore larger volumes of soil in search of the things they need.
When more nutrients are encountered in the course of this activity, plants can also acquire them more effectively; for the uptake of many essential elements requires the expenditure of metabolic energy, and the enhanced availability of carbohydrates typically provided by atmospheric CO2 enrichment tends to promote this process.
** For additional peer-reviewed scientific references and an in-depth discussion of the science supporting our position, please visit Climate Change Reconsidered: The Report of the Nongovernmental Planel on Climate Change (www.climatechangereconsidered.org), or CO2 Science (www.co2science.org).