All that water is just gold

Move over the carbon footprint and food miles, we're moving to the water footprint - the measure of the total amount of water it takes to deliver a product or service. JILL GALLOWAY talked to Brent Clothier, from Plant and Food Research, about water use.

How much virtual water have your jeans taken to make and sell? There's the water it has taken to produce the cotton on the plant, dye it, manufacture the jeans and then send them to New Zealand. Plenty of water used each step of the way.

Someday soon, your jeans may have their water footprint, as well as their carbon footprint, on the label.

Here's the good news.

New Zealand is the lucky country, Australia, not so lucky.

There is plenty of water in most parts of New Zealand, and agriculture and horticulture are major users.

Because we export a high proportion of our agricultural production, we are effectively a major exporter of virtual water, environmental scientist with Plant and Food Research, Brent Clothier, says.

"Australia should take our apples [fireblight aside], and our wine," he says. Dr Clothier is an expert on virtual water use and is one of many scientists working out how much water it takes to produce olives, kiwifruit, grapes, jeans or a litre of milk.

"With carbon, it goes into the atmosphere and is an issue for all the globe. That is not the case with water. We should be exporting virtual water from water-rich countries, to those that are water-poor."

Dr Clothier says it is all about using water wisely and the warmer the Earth's climate becomes, the more water-wise people have to be.

The countries that are in the best position are those such as New Zealand, Canada, Scandinavia, parts of Russia, Brazil and Britain.

The water shortages predicted as the Earth warms are in the midwest of the United States, California, Central America, Chile, Argentina, South Africa and Australia. "It also includes, in particular, the Middle East and North Africa. They are all facing water shortages and they are all areas which are currently big food producers."

Dr Clothier talks about the emerging nations of Brazil, Russia, India, and China, which aren't too badly off.

"That might not help areas of India and Bangladesh, when all the rain might come in big dollops. China has north-south problems with its water. There will be parts of China, the southern regions, where there are few people that will get the rain. The northern sector is drier and has a lot of the population."

He explained virtual water.

"We talk about three types of virtual water. Green water, which falls as rain and is stored in the soil, blue water is that which is in lakes, rivers or aquifers and is used for irrigation. Then there is grey water."

That covers water that comes out from crops or animals that carries fertiliser and/or pesticides and needs to be diluted to get it back to the stage it was at when it was first used.

As the world's population increases, there will be more pressure on the precious water resource, for food production and for people to use.

"Spain knows that the world is eating more olives and olive oil, and they are dryland plants, but does it make sense for a country short of water to plant more olive trees using irrigation for the future?

"Global warming means the Mediterranean will be even shorter of water in 2090."

Is it a smart move for the Spanish to grow olives, Dr Clothier asked. There has been a lot of water footprint work done in Spain and the sustainable amount of water an olive tree requires is now better known thanks to recent research, he says.

Trees, plants and people are big water-users.

The amount of water used for the production of goods and services are big amounts.

In fact, they are scary.

New Zealand is largely unaffected by water shortages.

"We have the blue water resources, if we use them wisely and don't create grey water."

The prospects for New Zealand as a food producing nation are exceptional.

"Under population pressure, food is going to be a key issue and water is going to be a key issue around food."

New Zealand has a richness of water, and is used to it, but Dr Clothier is not complacent about it, as some of that water can be in the wrong place at the wrong time.

"The early Canterbury irrigation schemes were notoriously inefficient. The drive now is to allocate water wisely."

Part of any decision-making is the need to know how much water a plant or tree needs.

"We have devices that put a small heat pulse into a plant.

"It heats the sap and we measure the heat wave as it moves up the plant. It tells us how much water the plant uses at that time."

Dr Clothier is at the forefront of that work, internationally.

"Someone says a grapevine or kiwifruit. How much water does it need? Ask it. That's what those devices can tell us."

Dr Clothier reads widely.

He is also an action-man. In the past he was a marathon runner, but since his knee has packed up, he has taken to roller blading. He has photographs of him bungy jumping.

Dr Clothier brings that same energy to the science of careful water use.

"The UK government's chief scientist, Professor John Beddington, said that the world faces a "perfect storm" of problems by 2030. Food, water and energy shortages will unleash public unrest and international conflict."

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.

The formal protocols were being established to develop a universally accepted formula for measuring water consumption, but that was five years away, he said.

Dr Clothier says that something like 75 per cent of New Zealand's irrigated water allocation does go to agriculture.

"So allocate it wisely and use it wisely."

- © Fairfax NZ News