Friday, August 31, 2012

Virtual Water

Export and import flows of water are inherent in the trade of food, since ag requires on average 85% of the freshwater supplies in a country.  An article by J. Carr, P. D'Odorico, F. Laio, L. Ridolfi, and D. Seekell in EOS has a stunning illustration of this

The green and yellow dots show the growth (green) and decrease (yellow) of exports/imports.  The analysis is more difficult because trade in food is itself ephemeral depending on local harvest conditions, which as Judy Dearest, would say, is naturally variable (except, of course when it is not).  Having said that some interesting points from the article are that only a few countries dominate the export market, The US, Canada, Brazil, Argentina and Australia, but the last has shown little change in the past twenty years.

Surprising to Eli was that the US exports virtual water (ie. food) to Mexico on net, and that the FSU is such a strong importer.  Less surprising is to see how China has become dependent on imports from Brazil, and not surprising at all is that money talks if you are going to need to import virtual water.

Why move icebergs around when you can transport ice cream?


David B. Benson said...

Ukraine and the 'stans are now seperate countries. Food grown there; Russia just exports natgas, petroleum products and timber.

Anonymous said...

Any Australin looking at how much water our country exports must be scratching their heads, given the general dryness of the continent. I suppose it's a reflection of the fact that ours is also generally a non-fertile country, which has helped keep the population low, and that it's a First World and a quarry country, which has kept the population rich: altogether these factors (and others) allow us to sell our limited water resources overseas.

The question for Australians is how much longer can we continue to do so?

Bernard J. Hyphen-Anonymous XVII, Esq.

Sou said...

The result for Australia is curious, particularly given the continued improvements to productivity (plant breeding, more efficient water use, improved farm technology practices etc). I'd suggest some hypotheses:

a) A growth in domestic demand - with both exports and imports increasing at the same pace.

b) Too many big floods and big droughts.

c) Limits to productivity improvements in some areas.

a) is possible, but our population isn't growing that quickly and we produce way more for export than for domestic consumption, so I doubt it's a factor.

b) is definitely possible, particularly this past ten years or so.

c) there have always been areas where the limits of sustainable production have been pushed to the limit, and I doubt that's a big factor.

There's at least one other possibility - that the data is incorrect. Haven't checked.

David B. Benson said...

Mexico imports from the USA due to NAFTA and rgww US Food and Farm Act's subsidies to US farmers; Mexicans cannot compete well any longer.

Anonymous said...

the US exports virtual water (ie. food) to Mexico"

The fact that we (the US) suck the Colorado (real water) nearly dry before it ever reaches Mexico certainly doesn't help them any in that regard.


Russell said...

Having the Sea of Cortez were it s doesn't help either.

Anonymous said...

By law (eg, Colorado River Compact), Mexico should get a certain share.

And, actually, the river does not even reach the Sea of Cortez these days- -which is entirely within Mexico, at any rate (despite the name, Baja California, is also part of Mexico.)

What was once a lush delta teaming with wildlife has all but dried up.

And it's only going to get worse with climate change and continued development in the southwestern US (which is using up water faster than it can be replenished, eg from underground aquifers)


Brian said...

I spent all day yesterday touring agricultural water conservation practices in California's Central Valley. Even seasonal crops are drip-line irrigated there.

Most of water efficiency gives results not in decreased use, but increased production. Yields per unit of water have increased. There's some decreased use as well, but farmers' perspective isn't that conservation should mean using less water but in making more money. Wrestling with that in an arid state will take some effort.

Anonymous said...

Most of water efficiency gives results not in decreased use, but increased production"

In Arizona -eg, Tucson, where I used to live -- it's even more perverse.

They ask ordinary" people to "conserve" (in fact, they can fine you if you don't -- if you use too much to wash your car and it trickles down the street) but then allow (and even encourage) development out the yin-yang (especially of water intensive things like golf courses).

If the golf courses etc aren't bad enough, many of the businesses actually have "outdoor air conditioning" misting systems (or at least did when I was there in the 90's).

Tucson is living on borrowed time, quite literally. They are sucking water out of the ground far faster than it can be replenished and the water table has dropped hundreds of feet in some places (with big sink holes sometimes opening up and swallowing houses)

My guess is that 50 years from now, Tucson will be a ghost town -- or at the very least, much smaller than it is now.