A Royal Society research team member, Jules Pretty, says the team took into account a number of changes that are expected in coming decades, such as climate change, massive rises in world population, and new consumption patterns.
VOA: standard.2009.10.21
But while U.S. usage has remained flat, China's oil consumptionrises about 5% per year.
As demand rises in China and protein consumptionrises even faster, this requires the intensive growing of grains for both foods and for renewable energy.
In fact, in some cases the worst excesses are seen among more affluent groups - for example, the largest rises in alcohol consumption have been seen in the higher income groups in recent years.