The Best Australian Science Writing 2013 (33 page)

Livestock's Long Shadow
has cast its own long shadow over the livestock carbon dioxide emissions debate. Richard Eckard, associate professor with the Melbourne School of Land and Environment, along with many other scientists, disputes the report's claim that livestock contributes 18 per cent of the world's
emissions, as it counts both cattle not raised for consumption and land not in fact used for livestock.

Eckard and fellow scientists say
Livestock's Long Shadow
overestimated how much of the land clearing in the Amazon was for livestock – when up to 40 per cent is cropped with soybeans. Eckard adds: ‘You have all the cattle in India for religious reasons, the cattle in Africa used for transport and wealth generation – a lot do not get consumed'.

Deforestation figures highly in
Livestock's Long Shadow
's sums, but Eckard points out much of Australia's rangelands were never cleared. ‘All the northern rangelands, they weren't cleared, they were just stocked with cattle,' he says. In fact, most clearing, in Australia, has been for cropping.

Ross Garnaut's
Climate Change Review
, updated in 2011, reported that although greenhouse gas emissions from livestock accounted for about 10 per cent of Australia's total, those emissions have declined by 13 per cent since 1990, largely because of a fall in sheep numbers – which dropped from 174 to 74 million. He pointed out that commercially motivated improvements in animal husbandry have ‘incidentally reduced emissions per unit of output. These developments could go further'.

The former chief of CSIRO Livestock Industries, Alan Bell, estimates beef cattle account for up to seven per cent of Australia's greenhouse gas emissions. And that figure is set to fall. Townsville-based CSIRO scientist Ed Charmley says recent work shows cattle in the northern rangelands are producing 20 to 30 per cent less methane than previous estimates. With about half the nation's cattle in the north, this means a significant downward revision.

Most of the world's livestock consume grass. Ruminant animals, such as cows and sheep, possess a special stomach or rumen which contains microbes that can digest grass – and a byproduct of that digestion is the greenhouse gas, methane. This
means ruminants produce protein from plants in areas that are unsuitable for any other agricultural activity.

Grasslands occur on land where the soil is too poor, the rainfall too low or the topography too rough for the land to be ploughed and planted with crops.

And before there were modern cattle there were wild ruminants, including the great bison herds of the US prairies and the wildebeest of the African savanna, which had adapted to these grassy regions.

George Seddon has argued the main herbivores in Australia were termites, which, interestingly, also produce methane. Eckard says that in the Northern Territory ‘it is quite feasible that termites are producing more methane on an area basis than livestock'.

Australia also has kangaroos, which, unusually among the large herbivorous animals, are not ruminants, and produce significantly less methane than cows, for example.

Methane, or CH
₄
, is a potent, if short-lived greenhouse gas. It is given a global warming potential rating of 25 times that of carbon dioxide. Methane is the main component of natural gas and coal seam gas. It is also produced from landfill, but the largest source of methane is wetlands.

Eckard explains the quantity of methane a ruminant produces is affected by its diet – a poor diet results in higher methane production – and by genetics. He says there can be a 15 per cent difference in methane emissions within one herd, determined by these two factors.

The steak-versus-lentils argument is further complicated by the fact that grasslands have been found to play another important role in keeping our atmosphere in balance: that is, they sequester, or fix, carbon that would otherwise be released into the atmosphere.

Helen King, former deputy director of the Co-operative
Research Centre for Greenhouse Gas Accounting, says:‘There is a lot of research that [indicates] if areas [of grassland] are not grazed, or are not managed, they actually take up less carbon, so grazing animals play a very active role in the carbon cycle. Wellmanaged grass-fed beef is a totally different proposition to growing grains to feed animals or growing grains for consumption'.

If people were to abandon eating red meat, some grasslands, like the Serengeti, might be repopulated by wild ruminants. But the more likely fate of Australia's grasslands would be consumption by fire. Bushfires, on average, burn over 500 000 square kilometres of Australia annually, mainly the grasslands in the northern half of the country. Bushfire accounts for about 3 per cent of the nation's net greenhouse gas emissions.

One of the charges made against livestock in general is that it consumes grains that would otherwise be used to feed people. But in Australia, livestock is largely fed grain and oilseed products that would not be used for human consumption.

Feeding grain to cattle doesn't bring great returns in the desired generation of protein: cattle require 8 to 10 kilograms of grain to produce 1 kilogram of meat. Pigs, on the other hand, require 3 kilograms of feed and chicken requires just 1.7 kilograms of grain to produce 1 kilogram of meat.

Australians are eating less red meat, anyway. Beef consumption has more than halved since 1977, to 31.7 kilos per person. Over the same period, consumption of chicken meat has rocketed from 15 to 45.2 kilos per person. The great Aussie barbecue has paled significantly, which is, on one level, in step with our aims of greenhouse gas reduction.

Every kilogram of beef produces 24 kilos of greenhouse gases. Pork and chicken (both products of non-ruminants) generate much less, at 4.1 and 0.8 kilos respectively.

And yet, ‘People say ruminants produce methane and are less efficient than pigs and poultry, but think about all that grain
that we need to produce protein from pigs and poultry,' Bell says. The argument has moved from red meat to meat and poultry generally.

Even Australian cattle don't spend their whole lives on grass; at any time, only about 2 per cent of the herd is in feedlots, being fed grain. Bell says feedlots are ‘a tough one for the environmentalists, particularly around methane'. Many environmentalists oppose feedlotting due to its intensive nature and the high-grain diet. But feedlot cattle grow more quickly than grass-fed cattle, and that means they emit less greenhouse gas before they're slaughtered for their meat. As a result, Australian grain-fed cattle are estimated to produce 38 per cent fewer greenhouse gas emissions than those raised on grass. They emit less again if they are administered Hormone Growth Promotants. In another context this would sound unpalatable, but here it makes sense.

Tara Garnett, from the Food Climate Research Network, at the University of Surrey in the UK, argues that if people didn't eat livestock, fewer cereal crops would be needed for livestock, but more would be required for humans.

Garnett also estimates that Britons throw out between 18 and 20 million tonnes of food a year. Australians are estimated to waste four million tonnes a year. Once, that food waste went to the pigs and poultry that were an integral part of farms and households – now it is simply wasted.

Animal products supply a third of all the world's protein. If we eliminated livestock we would have to produce half as much again vegetable protein crops to replace meat.

But in Australia the shift from pasture to crop land results in a reduction in soil carbon. Increasing soil carbon will be critical to Australia's future carbon balance. And the most effective way to increase carbon levels in soil used for agriculture is to return crop land to well-managed pasture, preferably native pasture.

And there's another problem. Crops need nitrogen, most of
which come from synthetic nitrogen fertiliser. Making nitrogen fertiliser is a very energy-intensive process, using at least 1 to 2 per cent of the world's energy supply. Then the fertiliser, once applied to crops, breaks down to become the potent greenhouse gas nitrous oxide, which has a global warming potential (GWP) of 298. The base unit for GWP is carbon dioxide, which is given a value of one at 20, 100 and 500 years. Methane has a GWP at 100 years of 25. There are other minor contributors, but carbon dioxide, methane and nitrous oxide are the three main greenhouse gases.

Organic farms fix nitrogen in the soil, naturally increasing its fertility through growing legume crops. And this lowers their productivity, because on a stockless farm, around one-third of fields are taken out of grain production for natural nitrogen fixing at any given time.

And here is the next conundrum for the environmentalist.

Garnett says that research into organic farms finds that, on the one hand, they are less energy intensive than conventional farming, but they are also less productive, so organic livestock is more greenhouse-gas intensive.

Bell hesitates to put a figure on the productivity of Australian organic farming, but says, ‘All the data I have seen, more from North America than here, says that organic is always going to be less efficient'.

Can you absorb another complication? Because … there's the issue of what it takes to produce meat substitutes.

A study by Cranfield University, commissioned by the environmental group World Wildlife Fund, reported that many meat substitutes consumed in Britain are produced from soy, chickpeas and lentils that are grown overseas and imported. A switch to these substitutes would result in more foreign land being cultivated, and raise the risk of forests being destroyed to create farmland. It also found meat substitutes tended to be highly
processed and involved energy-intensive production methods.

One of the study's authors, Donal Murphy-Bokern, said: ‘For some people, tofu and other meat substitutes symbolise environmental friendliness, but they are not necessarily the badge of merit people claim'.

While the UK imports all its soybeans from cleared Amazon forest, in 2011 at least, Australia grew about 14 per cent of its own soybeans, under fairly inefficient, water-sucking conditions. Ridoutt says consumers are demanding more transparent information about the water footprint and carbon footprints of their food. ‘In the States people are using their iPhones to download this kind of information, or reading it off bar codes.'

But he warns that everyone needs to understand they are dealing with systems that are more complicated than current apps or bar codes can handle.

‘The first point is there is no simple quick-fix solution, such as “Stop eating meat”, because it is a complex system – there are consequences and knock-on effects.' He cites the example of the push to ‘a more industrial meat-production system, based on chickens and pigs'.

Traditionally, a lot of these animals were raised on waste. Now, to make the productivity very high, very nutritious diets are being fed to them, so the land base that is supporting those forms of meat production is very much in conflict with the land base we might be using to produce cereals we might directly consume. You push in one direction, often it pushes out somewhere else.

In the meantime, something unexplained is happening to methane levels. Until 1999, as ruminant numbers rose, so did methane concentrations in the atmosphere. Then methane concentrations plateaued. No one is quite sure why. Bell suggests it
could be due to drought and human activities, such as drainage, shrinking natural wetlands. Or perhaps the number of ruminants hasn't risen so much.

It certainly raised questions in some quarters about the importance of ruminant livestock in global methane accounting, and in the value of attempting to reduce it. Bell says that in the past two or three years the atmospheric methane level has begun to rise again, but it will be a couple of years before climate scientists can call this a real trend.

So what is the environmentally conscious consumer to do? Australians have a unique alternative to farmed meats: kangaroo. Eckard says kangaroos and wallabies have a microbial digestive system, similar to ruminants, except the main byproduct is succinate. While they do produce some methane, it is significantly less per kilogram than the volumes produced by ruminants.

There are only a few studies on macropod emissions. The most recent, on red-necked wallabies in the Copenhagen Zoo, found they produced between 25 and 33 per cent of the methane of a ruminant, per unit of food ingested.

That's just one hop in the bucket, so to speak, but overall, Eckard questions whether the emphasis on reducing greenhouse gases should be placed on agriculture. ‘If we are going to have greenhouse gas emissions from something, is food production more legitimate than your transport preference?' This is the real nub of the question.

Fossil fuels consist of carbon, sequestered using the energy of the sun hundreds of millions of years ago. The scale of our consumption of this ancient carbon and sunlight is mind-boggling. Just four litres of petrol uses what was 90 tonnes of ancient life. In the space of one year, the world uses over 400 years of stored ancient energy and carbon.

As Helen King says, industrial use of fossil fuel is a oneway street. ‘Only the natural environment can take up carbon.
Industrial emissions put carbon into the atmosphere, but can't take it out again.'

There are so many conundrums for the consumer who wants to be environmentally conscious. If you walk or cycle to the butcher shop, take home some locally grown steak and cook it, to rare, over natural gas, is your carbon footprint smaller than if you'd driven to the supermarket, bought a soy-based product that was grown and processed overseas, then had to throw out leftovers because the kids wouldn't eat it?

One thing is clear: saving the planet is not as simple as giving up red meat.