Fig. 1: Energy and CO2 emissions intensity as a function of water-use intensity for 159 countries.

The figure shows the comparison of energy and CO₂ emissions intensity of different irrigation and pumping systems. a Energy intensity is expressed as the ratio of the energy consumed by irrigation to the irrigated area in a country (GJ/ha). b The energy intensity of each irrigation system (drip, sprinkler, and surface) or pumping system (diesel pumping and electric pumping) (MJ/m³) represents the energy consumption of five different irrigation and pumping system to pump and deliver one cubic meter of water. c CO₂ emissions intensity is expressed as the ratio of the carbon dioxide emitted by irrigation to the irrigated area³⁴ in a country (100 kg CO₂/ha). d The CO₂ emissions intensity of each irrigation system or pumping system is expressed in the same way as the energy intensity (g CO₂/m³). Energy and CO₂ emissions intensity reflect the average level during the 2000–2010 period. Mean values in the boxplot are shown with diamonds and median values are shown with midlines. Dashed lines in the figure are used to distinguish countries that are above or below the median energy and CO₂ emissions intensity per unit of water use.