Asa Wahlquist
Tonight as you eat dinner, think on this:
Every calorie of plant food needed one litre of water to grow it, while every calorie of meat or dairy products required ten litres of water. Generally speaking, fruit and vegetables need less water than grains, which use less than animal products. And grass fed animals use less water than grain-fed beasts.
That water might have been supplied as what we call green water, rain that fell and was stored in the soil, in pastures, or it might have been supplied as blue water, irrigation water. Now I am not going to sound like your mother, and say think of our dying rivers, and eat up all your food. But the reality is most of the water we waste is not from taking showers that are too long, or leaving the tap running while we clean our teeth, though those things are very important. It comes from tipping that last half cup of milk in the carton down the sink, or throwing out spoiled fruit and vegetables.
It takes 600 litres of water to make one litre of milk, and over 18,000 litres to make one kilo of butter. Orange juice takes 780 litres of water to produce one litre of juice, and some of you might be interested to know it takes less to produce one litre of wine – 360 litres of water.
The average Australian, I am told, eats around 2800 calories a day. That’s a minimum of 2800 litres of water – more if you eat animal products, dairy products in particular. In Brisbane, under the most severe water restrictions in the country, they are limited to 140 litres per person per day, and they are keeping to that. But they are consuming the product of more than 20 times that amount every day.
I think one of the most important things we can do is grow a lettuce, or a tomato bush. There is no alternative: you water it or it dies. That’s irrigation.
This week I met with the head of the world’s largest food company, Nestle, Paul Bulke. He told me the biggest problem the world faces is not greenhouse gas emissions, though he acknowledges it is important, it is not running out of oil, he reckons we can always hop on a bicycle – he’s from Belgium and I am sure has a different notion of distance to an Australian. No, Paul Bulke says the biggest problem the world faces is water. And he says Australia, because of our extended dry, is way ahead of Europe in understanding this.
When it comes to water, Australia is in a class of its own.
It is the driest inhabited country. Officially Antarctica is dryer: it gets less rain, but I just can’t think of Antarctica as a water deprived place!
Australia has the most variable rainfall in the world, thanks to El Nino. It is the flattest continent: less than one per cent of our country is higher than 1000 metres above sea level. Most of the country lies between 15 and 35 degrees south of the equator, the most arid latitudes.
The flow in our rivers is highly variable: variability is calculated by the ratio of its maximum to minimum flows. The Amazon has a ratio of 1:3, but the Murray is a highly variable 15:5, and the Darling River is just about off the scale, at 4705:2.
Incidentally, the annual flow out of the mouth of the Murray, before development, was less than one days flow out of the Amazon.
But I think the most important fact is that Australia has the lowest run-off in the world: run-off is the amount of rainfall that ends up flowing down the river.
In North America 52 per cent of the rain runs downs the rivers. In Asia it is 48 per cent, in Europe 39 per cent and Africa 38 per cent.
But in Australia the average is 10 per cent: and the figure for the Murray Darling basin is even lower, some are as low as just 2.4 per cent. Most of the rain that falls on the Murray Darling evaporates, or is used by plants or it percolates down into the groundwater.
Essentially the rivers of the Murray Darling basin are determined by evaporation, and that makes them particularly vulnerable to climate change.
Seeing the footprint of climate change in rainfall is not easy, because rainfall, especially in Australia, is so variable, and subject to cycles like El Nino, decadal variability and even cycles that are as long as 50 years.
The last three years in the basin were the warmest on record, with last year the warmest yet at 1.1ºC above average.
Australia’s annual mean temperature for 2007 was 6th warmest on record 0.67°C above normal, the 6th warmest on record.
Australia has recorded a warmer-than-average year for 16 of the past 18 years. This is in line with the rest of the globe. The World Meteorological Organization said that the global mean temperature for 2007 was about 0.41°C above average, making 2007 the globe’s 7th warmest year since records commenced in 1850. There is an overwhelming view from climate scientists contributing to the assessments of the Intergovernmental Panel on Climate Change (IPCC) that most of the global and Australian warming over the last 50 years is directly attributable to human emissions of greenhouse gases.
CSIRO scientist Wenju Cai has calculated that a one degree rise in temperature in the basin results in a 15 per cent reduction in river flow, or about 1850 GL less water in the river.
A gigalitre is one billion litres, or the amount of water in one square kilometre one metre deep.
There has been a long term decline in rainfall in autumn. Since 1950 Victoria has suffered a 40 per cent decline in autumn rainfall, compared with the long-term average. And that decline has been most severe in May. Cai says the decline “is not totally due to climate change, but it shows an imprint of climate change”.
Autumn rainfall is critical to crop growing, but it is also vital to running the rivers. Most of the water that flows down the Murray falls in winter and spring in the high country of NSW and Victoria. If the ground is wet after autumn rain, you get more runoff into the river.
On top of that, Victoria has experienced below average rainfall for the past ten years, since 1997, which is a year that crops up a lot when we talk about declining rainfall .
The CSIRO has just completed its biggest ever project, the sustainable yields survey of all the rivers of the Murray Darling basin. They looked at rainfall and run off, in the past, the present, along with water use, and projected what might occur under climate change.
But in the northern rivers of Victoria, their inflows over the past ten years are actually lower than the CSIRO’s climate change forecasts. As the head of the Murray Darling basin, Wendy Craik said. “We are there already.”
She said they expected to deal with it in 50 years time, not right now. She says “the question arises, have we arrived and is this what the future is going to hold for the southern part of the basin, or is it going to get worse?”
Rainfall has been below average, but Wendy points out “average rainfall no longer results in average inflow”.
At this point I want to explain how dams and rivers fill. Basically, any change in rainfall is amplified in run off. So if rainfall declines by 10 per cent, inflow declines by 20 per cent. As the catchment dries it needs more water to soak in, before you get runoff.
Less frequent rainfalls, means fewer chances to soak the soil and get runoff.
The result can be seen in the figures for Sydney’s Warragamba dam.
Between 1991 and 2006 the rainfall fell 24 per cent the long term average, but the inflow fell 72 per cent, from 2153 gigalitres to just 614 GL which is what Sydney was using before water restrictions.
The other side of the coin is that when you get big rains, the soil is soaked and subsequent rainfall flows into the dam. In the month of June last year, 450 mm fell on the catchment and Warragamba dam rose from 37% to 57%.
A report by the Victorian government estimated the Campaspe River has been 69 per cent below average, the Broken River 48 per cent below, while the Goulburn and the Murray Rivers have both been 38 per cent below the long-term average.
The long term average flow in the Murray is 6,595 GL.
Under medium climate change in 2055 it is forecast to fall to 4,500 GL. But the continuation of the last ten years of low inflows would result in just 3,700 GL.
The amount of water licensed for extraction from the Murray is 4900 GL.
But in 2007 inflow was less than half the amount licensed for irrigation, 2100 GL, the year before, 2006 the inflow was one quarter, 1220 GL, the lowest on record. Clearly there is not enough water flowing into the rivers to provide for irrigation and towns, let alone the needs of the river and its wetlands.
Along the Murray and Murrumbidgee, in 2006/07, irrigation was reduced by 43 per cent It has been further reduced in 2007/08, to 15 per cent of the licensed volume and this year is looking to be even worse.
On top of that the lower lakes is facing catastrophic acidification, as acid sulphate, held bound safely in the soil, under water, becomes exposed to air and turns into sulphuric acid. It is the kind of change from which there is no recovery. And although attention has been focussed on the lower lakes, there are literally thousands of sites in the basin, wetlands and creeks and rivers, at risk of acidification.
That is why the Federal Government is spending $3.1 billion buying back water licences, and the Wentworth Group of Concerned Scientists is calling for irrigation allocations in the Murray Darling Basin to be halved.
It wants the ten year water buyback to be brought forward and to take place over the next two years, and the $5.8 billion allocated for infrastructure upgrades to be spent buying back water.
In its submission to the Senate Inquiry into the provision of water to the Coorong and Lower Lakes, the Group said their analysis suggests that the consumptive use of water across the Murray Darling Basin may have to be cut by between 42 and 53 per cent.
The impact of such a cut back would be profound, and not just for the communities who rely utterly on the basin. It is a feature of irrigation farming that most of its products are processed locally, in dairy factories, wineries, rice mills, cotton gins that are huge employers in regional Australia.
Australia used to grow enough food to feed 70 million people. The failure of two wheat crops in a row, last year and the year before, something that had not happened since the 1940s, was a contributing factor to the run down in the world wheat supply.
In six of the past seven years, demand has outstripped supply. Then, last year, virtually every major grain growing area was damage by climate events, from drought to floods. At one stage earlier this year, there was just 30 days supply of wheat left.
Food security has not been an issue since the time of the first fleet, who incidentally arrived during the mother of all El Nino events, and drought nearly wiped out the colony.
But the global dynamics around food are changing rapidly. This year we saw shortages of wheat and particularly rice. The results was rising prices, and food riots.
The causes were largely the increased demand for animal products in China and India.
Those animal products are largely poultry and pork that are fed on grain.
Every year in China, 30 million people move from life as a poor peasant to living in a city, from eating three meals a day to eating animal protein. And that means more grains: basically it takes 7kg of grain to produce one kilo of beef, while one litre of milk, or one kilo of poultry or pork needs two kg of grain.
There are a number of other factors, like the reduction of research funds in agriculture by governments that thought world food problems had been solved, but the emerging problem last year was biofuels.
Which brings me back to water. According to the chairman of Nestle, Peter Brabeck-Letmathe, huge quantities of water are needed to produce biofuels. He says it takes up to 4,000 litres of water to produce one litre of so-called bioethanol, and up to 9,000 litres for a litre of biodiesel. Remember it takes 3,000 litres to produce enough food for one person to eat a day.
About 240 kilograms of corn is required to produce 100 litres of ethanol, enough to fill the tank of a modern four-wheel drive. And ethanol has just 2/3 the energy of gasoline, so you need more ethanol.
I am mindful that here we are at some distance from the Murray Darling basin. I’ve been having a look at local statistics. I note that Laurieton has an enviable average rainfall of 1536 mm. In the years since records were first kept, in 1885, the highest rainfall was 3245 mm in 1963, the lowest was 748.2 in 1915. That’s a multiple of 4.3 in case you are interested, it is a highly variable rainfall. Like much of Australia, the wettest decade was the 1950s. Every decade since then has been drier than the last. The only period drier than the seven years of this century was the first decade of last century, the period of the terrible Federation drought.
One of the best reports on water, called water for our cities, published last year, had a great graph of the water supply to Brisbane, Sydney, Melbourne and Perth.
To summarise the graphic, both Sydney and Brisbane have more stormwater run off those cities than is supplied to residents. In addition, they also have a large quantity of wastewater. The conclusion is neither of those two cities should ever run out of water, to quote the report, “a considerable excess of water is available in our cities that has not been utilised. The challenge is to find economic ways to harvest and utilise this water”.
What this means for Laurieton, as a town half way between the two, with a higher rainfall than Sydney (Syd: 1215 mm) is you are well supplied with water, if you can access it. In Sydney and Brisbane the problem has been what I call Big Water has literally monopolised supply. For a long time rainwater tanks were banned. The NSW government has fought tooth and nail against a private company that wanted to access the sewers and re-use the 450 GL of sewage that is currently pumped into the ocean. There are a lot of solutions, but only a few – like desalination – make money for the big water monopolies.
Our water supplies were nearly all built during the wet decades, of the fifties, seventies and eighties. Across all of southern Australia, rainfall is now far lower than it was then. Every 50 years there is a big dry, it happened in the 1940s, the Federation drought, the 1860s and at settlement.
It is clear our planners did not take into account a reversion to those low periods.
But there is something else happening. There is no doubt Perth’s rainfall has declined, due to climate change. There are two distinct steps down, one in 1974, another in 1997 and possibly a third in 2001. They now get 24 per cent the inflows into their dams that they did prior to 1974. They get over half their water from groundwater, with terrible consequences on that aquifer, They have one desalination plant, and are building another.
Melbourne just had its driest September on record. It has been dry since 1997. Is it climate change? Scientists aren’t sure yet, but it has certainly got them wondering.
This poses huge problems for water planners. The past is no guide to the future.
Within the last five years. all the mainland capital cities have gone onto water restrictions, and all are building, or considering building, desalination plants. The Big Water solution.
I would argue there are many things we can do, from being water conscious to installing rainwater tanks, and lobbying our local governments to save and use stormwater.
I will finish with two things, my mentor Peter Cullen, said.
The first is: ‘I have always felt that knowledge was better than ignorance, and we should try knowledge, because ignorance has not got us very far’.
The second is that debates about water are really debates about the sort of society and environment we want to live it. I would encourage to inform yourselves and be heard.