First there was carbon foot-printing, then food miles, and
soon the world's consumers will be told how much water was
used to produce their food.
Scientists say New Zealand exporters have little to fear from
what are known as "virtual water measures", and the low rate
of exploitation could be a competitive advantage over other
food producers.
Virtual water measures calculate the volume of water used to
produce a product or service.
A cup of coffee, for example, requires 140 litres of water,
mostly to irrigate the coffee plant.
Plant and Food Research group leader of systems modelling
Brent Clothier told a Science Media Centre conference
yesterday each year New Zealand exported 500 million cu m of
water to the United Kingdom through exported products.
This equated to a water-stress index, or the percentage of
New Zealand's total available water used, of 0.8%.
Dr Clothier said countries such as Italy and Spain, which
exported similar volumes of water to the UK through their
exports, had a water-stress index between 60% and 80%.
Zespri innovation manager Alistair Mowat said a water measure
could prove favourable for New Zealand exporters.
"For New Zealand, it is a new area, and potentially it
provides us with a competitive advantage," he said.
Dr Clothier said large global retailers Wal-Mart, Tesco,
Sainsburys and Marks and Spencer were all looking at
environmental labelling of food, including a virtual-water
footprint, and some had said water use would be a factor in
deciding which suppliers they used.
Formal protocols were being established to develop a
universally accepted formula for measuring water consumption,
but that was five years away, he said.
Water New Zealand chief executive Murray Gibb said depleted
water resources caused by a growing population, urbanisation
and changing diets could become a global problem in 20 years.
He agreed that New Zealand would rate favourably with its
water use in food production, saying just 2% of water run-off
was harvested for use compared with the inter-national
average of 50%.
Mr Gibb said Canterbury, considered by many New Zealanders as
an area where water was being exploited, also compared well,
with just 8% of water flowing over the plains or in aquifers
being harvested for agriculture.
Mr Mowat said water foot-printing was two to three years
behind carbon footprinting, and the next step for New Zealand
was to develop a water-footprint measure for a horticultural
crop and then look at the risks and opportunities that might
come about.
Mr Mowat said there was a risk that consumers could be
bombarded with a variety of environmental measurements for
carbon, food miles and water.
However, carbon foot-printing and work being done by the
large retailers would give a lead on how to communicate the
information to consumers, he said.
