Let’s make a bet. I bet you that within the next five years, the biggest sustainability issue to hit the beef industry won’t be carbon emissions, hormone implant use or ethanol prices, it’ll be water use. Conflict over water rights and declining aquifer levels are already occurring in many areas and those battles will only increase as urban sprawl encroaches onto agricultural land.

Fortunately, scientists at the University of Twente in The Netherlands have calculated the water footprint* of humanity. Published in the highly prestigious Proceedings of the National Academy of Sciences, this study provides valuable evidence as to water consumption across different regions. Within the paper, beef production is singled out as contributing 6.7% to global water flows – less than cereals at 17% or industrial products as 12.2%.

Yet the message accompanying press coverage of the report is anything but positive for conventional beef production – a  ScienceNow press release (tagline: “Up to the minute news from science”) quotes Sandra Postel (director of the Global Water Policy Project) as saying:

…people can opt to eat less meat or to switch from grain-fed beef—which, again, requires about 5300 liters of water for each dollar’s worth of grain fed to a cow—to grass-fed beef, which typically requires only the rainwater falling on a pasture

Interestingly, the 5,300 liter (1,400 gallon) figure is not mentioned in the PNAS study, indeed there is no evidence as to the source for Ms. Postel’s claim. Furthermore, the figure is worthy of an award for what must be the most incomprehensible units ever assigned to water use. Expressing water use per acre or per unit of beef produced gives a solid foundation for understanding and comparison, but a volume unit per economic unit of feed fed to a beef animal? What happens when corn hits $10/bushel or falls to $3/bushel?

It’s a sad reflection upon my social life (or lack thereof) that I spent an hour last night calculating water use per dollar of corn fed. The entire calculation can be seen in the excel spreadsheet below, but in essence we simply need to know the current corn price ($6.335/bushel), the proportion of corn that is irrigated in the USA (15%), water use per acre of irrigated corn (2.1 acre-feet) and corn yield per acre (147.2 bushels).

Using these data, 110 gallons of water (417 liters) are used per $ of corn grain fed to a feedlot steer (equivalent to 44.9 gallons of water per lb boneless beef). That’s in line with the total water use of 367 gallons/lb boneless beef cited by Beckett and Oltjen at UC Davis.

Ms. Postel’s estimate is 12.7x higher than average USA data suggests. An error of this magnitude is huge and has the potential to do immense damage to the beef industry, especially when it’s used as a divisive argument against grain-fed production systems. Yet it’s published as factual data in a scientific press-release (without the need for citations or supporting evidence) and will be read by thousands of consumers with an interest in science. Just imagine the reaction from PETA and HSUS if the beef industry quoted environmental figures unsupported by science – instant loss of credibility.

As an industry, we need to be proactive and conduct assessments of resource use and environmental impact before the anti-animal groups or “impartial” environmental groups produce numbers for us. If we continue avoiding science for fear of what it might reveal, we may soon be reacting to a loss of consumer confidence and market share, rendering long-term sustainability impossible.

* Total water use by humans

Water use spreadsheet