You create two tons of carbon dioxide a year just from eatingS

Reducing our carbon footprints definitely won't be easy. Indeed, 20% of all carbon dioxide emissions come from people eating - and digesting.

Researchers at Spain's Universidad de Almería has determined that all food-related CO2 emissions add up to about 2 tons of carbon dioxide and 20 gigajoules of energy per person every year. That number encompasses everything from when the food is produced to when humans excrete it, and altogether that accounts for a fifth of all the world's CO2 emissions.

Although the initial act of producing food, particularly food from animals, has the biggest carbon footprint, the next biggest factor is human excretion. This is the first ever study to include pooping in an investigation of carbon emissions, and the results predictably enough aren't pretty. Chief researcher Iván Muñoz explains:

"Human excretion contributes significantly to water polluting through providing organic matter and nutrients, such as nitrogen and phosphorus, which fosters the growth of algae, a decrease in the level of oxygen dissolved in the water, bad smells and other problems associated to eutrophication," Muñoz says, "although such effects are minimised by the purification processes performed before wastewaters are discharged into rivers or to the coast. The problem is that in many cases our rivers have a very low water level and find it difficult to soak up wastewaters, not only from excrements, but also from other sources such as pesticides and fertilisers used in farming and pollutants from industry."

[The International Journal of Life Cycle Assessment]