Figure 3.

Percentage of global crop production area (black bars) and percentage of peer-reviewed publications listed in the web of science citation database (ISI, Thomson Inc., Philadelphia, PA) with the following search terms: climate change or global warming (white bars), drought (light grey bars), temperature and climate change or global warming (hatched bars) and elevated CO₂ (dark grey bars) for (a) the six most widely grown crops and (b) C₃ (wheat, rice, soya bean and barley) and the C₄ (maize and sorghum) crops.