Friday, March 23, 2012

Agriculture Uses 92% of the World’s Drinking Water by Heather Carr

                                          Irrigation of vineyard in Thailand photo via Shutterstock

A new study shows that agriculture consumes 92% of the world’s fresh water used each year.

Arjen Hoekstra and Mesfin Mekonnen of the University of Twente in Enschede in the Netherlands divided the surface of the earth into blocks of 85 square kilometers or less and looked at water consumption patterns for agricultural, industrial, and household uses in each block. The study looked at the years 1996 to 2005.

In that time, people used an annual average of 9087 cubic kilometers (about 24 quadrillion gallons) of fresh water for all uses. Unlike many other studies, this one took into account the fact that water is often recycled and reused many times before it goes into the sea.

The study also looked at “virtual water”, or the water embedded in the creation of a product.  A previous study found that it takes about 5300 liters of water to grow and process a dollar’s worth of grain, something that’s not obvious when looking at a sack of flour in the grocery store.

Many countries lack sufficient water to produce necessary goods, so the crops are grown and processed in other couuntries, then imported, or material goods, such as electronics, are created and put together, then imported. About 22% of the water consumed worldwide is virtual water that has moved across national borders.

Some interesting numbers from the study:
  • Agriculture accounts for 92% of all water usage.
  • 27% of worldwide water consumption goes to growing cereal grains (wheat, rice, corn, etc.)
  • 22% of worldwide water consumption goes to raising meat animals
  • 7% goes to dairy production
The authors go on to suggest that improvements in irrigation and simple changes in our diets can reduce our water usage.

No comments:

Post a Comment