Introduction
The continuing rise in atmospheric carbon dioxide concentration ([CO2]) is a major factor driving global warming and associated climate change (Forster et al., 2007). Atmospheric [CO2] is expected to reach 550 L L−1by 2050 according to the Intergovernmental Panel on Climate Change (IPCC) under emissions scenario A1B(Carter et al., 2007). This is a nearly 50% increase from about