Nearly a quarter of the energy processed by land plants is either harvested by humans or lost due to our activities, according to a global analysis of agricultural production. In parts of the world where human activity is most intense, such as Europe and southern Asia, more than half the energy processed by plants is appropriated by people. The figures ... indicate how difficult it will be to increase agricultural production to feed an ever-growing global population or find sources of biofuel to replace oil and gas.

The researchers used huge data sets from the U.N.'s Food and Agriculture Organization on agricultural production in 161 countries and combined this with a global climate model, which predicted the natural productivity of different climatic regions if they were not converted to agriculture. 'We wanted to quantify the human domination of ecosystems,' said team member Karlheinz Erb at Klagenfurt University in Vienna. The results are published in the Proceedings of the National Academy of Sciences."

Source: Guardian