Boys and goats in the rain in Western Kenya (photo credit: ILRI/Stevie Mann).

Brad Ridoutt, a principal research scientist with the Commonwealth Scientific and Industrial Research Organisation (CSIRO), Australia’s national science agency, is an international leader in the field of life cycle assessment, which he applies to agricultural production, food systems and sustainable healthy diets. Ridoutt has an interesting comment on livestock water ‘hoofprints’ which makes up part of a longer article of his, An update on water footprints, posted on Tara Garnett’s Food Climate Research Network (FCRN) site on 7 Feb 2016. Ridoutt’s (cautionary) livestock comment follows in full.

A comment on water footprints of livestock products, by Brad Ridoutt

‘. . . Livestock and livestock products have been of considerable interest to many FCRN members. There have also been some rather outrageous statements made about the water footprint of livestock products, including claims suggesting the water footprint of any animal product is larger than the water footprint of crop products with equivalent nutritional value (Mekonnen & Hoekstra. 2012. Ecosystems 15:401–415). These claims are based on virtual water studies which, although bearing the name water footprint, are not compliant with ISO 14046.

The first thing that needs to be stated is that agricultural production systems are highly diverse—so there are differences in how livestock rearing and crop production are practiced.

In addition, the local environmental contexts where farming is practiced vary—such as variation in local water scarcity.

Broad brush claims about the footprints of entire categories of agricultural or food products are rarely, if ever, truly representative or useful.

‘To take an example: in the Australian State of New South Wales, the water scarcity footprints of six geographically defined beef cattle production systems were found to vary from 3.3 to 221 L H2Oe per kg live weight (cradle to farm gate). The unit H2Oe is analogous to the CO2e used in the reporting of carbon footprints, except that the unit of equivalence is water consumption at the global average water stress index (based on http://www.ifu.ethz.ch/ESD/downloads/EI99plus [link is external]).

The main message is that the variation in water footprints is large, even within just one part of eastern Australia.

‘In another study, the water scarcity footprint of lamb cuts produced in western Victoria (Australia) and exported to the USA for consumption was 44 L H2Oe per kg (cradle to grave). The water scarcity footprint of milk produced in Victoria’s South Gippsland region was 1.9 L H2Oe per L (cradle to farm gate). For wheat produced in New South Wales, where there is very limited use of supplementary irrigation, the water scarcity footprint ranged from 0.9 to 152 L H2Oe per kg grain (cradle to farm gate).

Although there is no basis to make a direct comparison, as beef cattle and wheat have different pathways of transformation into food products which are eaten and they contribute to diets in different ways, the ranges in farm gate water footprints for beef cattle and wheat in New South Wales were largely overlapping.

If anything, these results should evoke caution in making simplistic characterizations of the water footprints of different types of foods and diets.

Read the whole article, An update on water footprints, by Brad Ridoutt, Food Climate Research Network, 7 Feb 2016.