[Water_news] 5. DWR'S CALIFORNIA WATER NEWS: AGENCIES, PROGRAMS, PEOPLE - 5/20/08

Department of Water Resources

California Water News

A daily compilation of significant news articles and comment

 

May 20, 2008

 

5. Agencies, Programs, People -

 

 

Green pedicure

Footprints in carbon, nitrogen and water

The Economist – 5/19/08

 

CARBON footprints have become a widely accepted way to measure and describe humanity’s impact on the planet. But in principle, one can work out any kind of footprint. One’s turnip footprint would be the number of turnips (or root-vegetable equivalents) consumed in a lifetime. It wouldn’t be useful because it doesn’t capture anything that the world actually needs to know. That’s an important point when calculating a footprint: what is to be measured?

 

A carbon footprint measures greenhouse gases produced by any activity. The father of the carbon footprint is the ecological footprint, which was introduced in the 1990s. It calculates the productive land and aquatic ecosystems needed to produce the resources and assimilate the wastes of any given human population.

 

But there are other kinds of footprints, such as the nitrogen footprint, an idea being developed by James Galloway of the University of Virginia. Forms of reactive nitrogen—including oxides of nitrogen, ammonia, ammonium and urea—are being produced at an astonishing rate, mainly by burning fossil fuels (oxides of nitrogen), and making fertilisers (ammonia). But the release of reactive nitrogen is cascading through the environment, adding to global warming, respiratory ailments, acid rain and marine dead-zones. Much could be done to reduce its impact. But to do so a metric is needed for individuals, businesses, nations and activities.

 

Creating a nitrogen-footprint calculator will reveal some surprising information. It could well reveal that some forms of organic farming release more nitrogen into the environment than traditional or no-till agriculture. It would show that the world’s nitrogen rich (the United States and Europe) produce so much that it is mostly washed away into the sea. And it would reveal the world’s nitrogen poor (mostly in Africa), where decades of farming have stripped the soils of nutrients, and many farmers cannot afford to use the mineral fertilisers they need.

 

Water footprints are also in vogue. Traditional water-use statistics have been given in sectors, such as domestic, agricultural and industrial water use, but that tells you little about how much water a country actually uses. The water footprint provides a more accurate way to compare individual and national water use. According to one recent study, India uses more water than any other country, but America’s per capita use is highest at 2,480 cubic metres per person per year, followed by Greece, Italy, and Spain. China has relatively low water footprint of 700 cubic metres per person per year.

 

The water footprint is closely linked to the concept of virtual water, which is the volume needed to produce a commodity or service. Earlier this year, Dr John Allan from King’s College London was given the 2008 Stockholm Water Prize for introducing the concept in the early 1990s. He was studying the option of importing virtual water as a partial solution to problems of water scarcity in the Middle East. National, regional and global water and food security can be improved when water-intensive commodities are traded from places where they are economically viable to places they are not. Dr Allan wanted to import food as an alternative water “source” to reduce pressure on domestic water resources. It’s a clever idea that opens the way to more productive water use, even though it assumes that all sources of water—whether from rain, irrigation or desalination—are of equal value.

 

Now that virtual water is established, Dr Galloway and his colleagues are introducing the virtual nitrogen and virtual land concepts. For example, key meat-importing countries such as Japan are also bringing in virtual land, water and nitrogen, from meat-exporting countries like Brazil. Japan’s pig and chicken meat imports embody the virtual equivalent of 50% of Japan’s total arable land. Half of Japan’s virtual nitrogen is actually lost in the US. That might alarm the citizens of Louisiana and Texas when the Gulf of Mexico marine dead-zone (caused by nitrogen runoff) returns this summer.

 

Ultimately, these metrics bring to light the broad but subtle environmental implications inherent to various activities. Paying for them is another matter. But at some point, someone is bound to think of asking Japan’s meat-eaters to pay for the damage they do to the fisheries in the Gulf of Mexico.#

http://www.economist.com/displaystory.cfm?story_id=11394516

 

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