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05/22/2008
Water, Virtual and Otherwise
After last week’s column on alcoholic drinks, let’s discuss the
major component of those drinks, good old H2O. I see in an
article by Richard Kerr in the May 9 issue of Science that on
Sunday, May 25, Phoenix is scheduled to land on Mars. Phoenix
is NASA’s half-ton Mars lander that, hopefully, will touch down
gently on an area of Mars where water ice is believed to lie just a
couple of inches below the surface. The lander will then proceed
to scoop up samples of this ice, heat them and send the vapor
into a mass spectrometer to analyze the sample. I doubt that
anyone really expects it, but I’m sure the NASA/JPL people
would be absolutely ecstatic if they found compounds suggestive
of past or present life on Mars.
Actually, they’ll be ecstatic if Phoenix lands safely and the
instruments work as planned. Unlike the rovers that are to my
knowledge still alive and working on other sites on Mars, this
lander will have to survive a rocket-controlled landing much like
the lander that deposited our astronauts on the moon. Back in
December 1998 the Mars Climate Orbiter burned up in the
Martian atmosphere when someone failed to convert metric to
English units or vice versa. Only a few weeks later, the Mars
Polar Lander headed for the surface of Mars but was never heard
from again. Unlike the rovers, Phoenix will only perform for a
maximum of 90 days. Good luck, Phoenix!
Another article in the same issue of Science by Sarah Das of
Woods Hole Oceanographic Institution and others also deals
with water on a grander scale. The paper follows up on work
published several years ago indicating that water from melting
ice was making its way down to the bottom of the Greenland ice
sheet. Apparently, the water results in a lubrication of the
interface between the ice and the surface, resulting in a startling
acceleration of the ice sheet’s slide towards the sea. The earlier
study indicated that the rate of this slide was nearly 30 percent
higher than normal and there was concern that the increase
would lead to a rise in sea level of as much as a meter (about 3
feet) or more by the end of this century.
The new study would seem to confirm the fear of disaster soon.
The glaciologists observed the melting of water over a wide area
that included the area of the initial study six years ago. They
found substantial melting and one spectacular event. The
melting formed a sizable lake, which suddenly began draining at
a startling rate and was gone in less than two hours! The rate of
drainage the flow of water over Niagara Falls! The water
drained down all the way to the bottom of the Greenland Ice
Sheet and that month, August 2006, the ice sheet moved at a 48
percent faster than its 76 meters per year mean speed. That’s the
bad news. The good news is that they found that, at the sea
itself, the glaciers only moved only 9 percent faster than normal.
On the face of it, it seems that Greenland is still sliding into the
sea but not as rapidly as first feared. Hopefully, we have more
time to try to avoid submersion of our coasts but global warming
and our carbon footprints are still a worry. With oil at $129 a
barrel and gasoline in the U.S. at $4 a gallon, energy remains a
topic of increasing personal concern for everyone.
But this column is about water. Not only must we worry about
our carbon footprint but it’s also clear that we’ve neglected
another footprint, our water footprint. At the moment, we in
New Jersey are fortunate in that our reservoirs seem to be
sufficiently full that we needn’t be concerned on a local basis
until the next drought. But what about our “virtual water”
usage? I have to admit I hadn’t thought about virtual water at all
until I read an article by Thomas Kostigen in the June 2008 issue
of Discover magazine. I wasn’t familiar with the term.
Recently, I’ve read or heard more in the media about reducing
our carbon footprint by eating foods produced locally. I admit to
being guilty of enjoying those grapes and other fruits that come
from faraway places such as Chile. The energy that it takes to
fly them to distribution centers in the U.S. and the additional
energy to transport them to the supermarkets is hidden in the
prices we pay. It’s a dilemma. Should I forego the grapes and
save energy, thus lowering my carbon footprint but depriving the
Chilean farmer a market for his or her produce? In the summer
and fall months I do patronize our local farmers market.
Similarly, we should consider the water footprint associated with
various products, that is, virtual water. The term “virtual water”
was coined by Professor John Anthony Allan at Kings College
London in 1992. Virtual water is a calculation of the amount of
water needed in the producing a product from start to finish. If
you’re like me, you probably don’t think about your water
consumption except when you get the water bill or when there’s
a drought and you make some sacrifices in cutting down on
watering the lawn, flushing the toilet, etc.
In nearby New York there’s currently a controversy over whether
restaurants, particularly fast food restaurants, must post
nutritional information such as calorie counts on their menus.
Allan, who just won the $150,000 Stockholm Water Prize, has
teamed with Arjen Hoekstra of the University of Twente in The
Netherlands to promote awareness of virtual water by listing the
virtual water content on products’ labels.
A quiz in the Discover article reveals that tea is one of the most
efficient items, coming in at only 8 gallons of virtual water for an
8-ounce cup of tea. An 8-ounce cup of coffee, however, weighs
in at 37 gallons of virtual water, while a pound of beef takes
1,857 gallons of virtual water to produce. This compares with
575 gallons for a pound of chicken. Vegetables generally are
more water efficient than meats and the article says that
vegetarians on average consume 1,010 gallons of virtual water
compared to 1,414 gallons for the average meat eater. Other
products include what looks to me to be a woman’s leather purse
at 6,340 gallons of virtual water versus 713 gallons for a man’s
dress shirt. I certainly never considered how much water it takes
to clothe me.
Of the 10,460 cubic miles of freshwater worldwide, South
America has 30 percent, while we North Americans have 15
percent. Apparently, Europe has only about 6 percent of the total
freshwater compared to the Middle East’s 11 percent, which
surprised me. The article doesn’t break out China but gives a
figure of 17 percent for the Asia Pacific region. On a global
basis, the ideal situation would be for agreements to be made that
those water-rich countries would be the exporters of the high
virtual water products, allowing the water poorer countries to use
their water for food and other necessities and the ability to
market low virtual water products with any leftover water. At
least that seems reasonable to me.
Well, now I’m thirsty and will have a glass of water. Now I’m
wondering how much virtual water it takes to make a glass of
drinkable water here in New Jersey! Finally, a personal note of
thanks to our editor Brian Trumbore for the opportunity to spend
last evening with our Lamb cartoonist Harry Trumbore at a
Morristown theater, where Garrison Keillor kept us and a packed
house in stitches with his Lake Wobegon humor. I haven’t
laughed so hard in years.
Note: if you missed last week’s column, I noted there that
henceforth I’ll be posting my columns on Thursdays.
Allen F. Bortrum
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