Methane and livestock: factoids help farmers least of all

By Corey Watts
Posted on 24 August 2012
Filed under Agriculture, Food

By any traditional measure, Australia’s graziers and pastoralists have made remarkable achievements in a highly variable climate and a difficult global marketplace. Australian demand for meat and milk remains high and steady, and our exports are strong and growing. Animal agriculture isn’t going away anytime soon. At the same time, livestock production is an important contributor to the global warming, albeit one of many.

In my work with rural communities and industries, I still hear a lot of confusion on carbon and climate matters. In amongst the genuine questions is an assortment of factoids that downplay agriculture’s role in climate change.

Factoids are what myths become when repeated so often they are accepted as fact. Factoids are a worry. In a rapidly changing climate, one would think the more sensible way ahead for livestock producers is to empower themselves with the science needed to craft solutions that work for them as much as the public good. As the world economy shifts into low-carbon gear it is the carbon savvy who will profit the most.

A recent article on these pages sought to counter campaigns to (as the author sees it) ‘demonize’ cattle for the methane they belch and encourage vegetarianism. Much of what that article says lends the subject much-needed perspective and the author raises some good questions. In the pursuit of balance, however, she might have overstepped the mark somewhat.

Before we go any further, let’s back up a bit and look at the big picture: methane is an important player in global warming. That’s a fact. Atmospheric levels of methane are now at their highest for at least 650,000 years, rising by about 160 per cent since 1750, according to the IPCC. To date, methane is thought to have caused around 20 per cent of observed global warming.

Now, it’s certainly true that there are a plethora of methane sources, some natural, some not. The former includes wetlands, wild ruminant animals, termites, and even the oceans. Wahlquist points out that termites up the Top End emit a hell of a lot of methane.

Sure, OK, so what?

Surely the issue is about what we can control and not what we can’t? Most methane emissions today—more than 70 per cent—are our doing. Anthropogenic sources include leaky gas wells and pipes, coal mining, rice paddies, landfills, and deliberate burning of biomass (forests, savannahs, crop residues, etc.). Then there is our livestock. Estimates vary, but around 20 per cent of human-caused methane is directly attributable to animal production.

Ah, but what of all those wild beasts? Well, it’s thought that there are around 75 million wild ruminants roaming the planet today. Doubtless there were millions more in the past, perhaps scores of millions, but it’s hard to see their numbers ever reaching the more than three billion cattle and sheep grazing today. This represents a veritable explosion in the size of the planetary herd since pre-industrial times. Of course, the clearing and burning of vegetation for pasture is itself a major source of methane and other greenhouse gases.

So, any attempt to characterize livestock and grazing as natural (and, by implication, good) doesn’t wash, especially on a continent like Australia that never knew ruminants like these. That doesn’t mean that it’s a wholly bad situation. After all, billions of people, including many of the world’s poor, benefit from livestock. Indeed, the boom in livestock production shows little sign of diminishing.  As demand, particularly in East Asia, really takes off the world will have to manage almost five-and-a-half billion cattle and sheep by mid-century

But wait, methane lasts only about twelve years in the air, broken down (so to speak) by a combination of atmospheric chemistry and sunlight. So, if methane exits the sky so quickly, what’s the problem?

While methane is a short-lived compound, it’s not as if its sources have gone away and it will all magically disappear in twelve years time.  In fact, over the long term, the concentration of methane in the air shows a nett growth and it’s growing still. The suggestion that booming global stock numbers have played little or no part in this is a lot to swallow.

A popular myth has it that cattle and sheep are essentially carbon neutral. Cows eat carbon in the grass, the reasoning goes, which is then returned to the atmosphere when they poo, burp, fart, die, etc., only to be sequestered in pasture growth later. It makes perfect sense until you grasp the power of methane as a greenhouse gas.

It’s still a carbon-based molecule, but the methane burped out of a cow is considerably more powerful global warming agent than carbon dioxide. Molecule for molecule, over a given century, methane outdoes carbon dioxide by 25 to 1 in the warming stakes. (Over a twenty-year period methane’s ‘global warming potential’ rises to 72.).

Often cited is a 2009 CSIRO report for the Queensland Government suggesting that hundreds of millions of tonnes of carbon—much more than all our livestock emit—could be soaked up in Australia’s grasslands. The fine print, however, reveals that these humungous figures refer to what is theoretically possible, not what is practical. That figure is bound to be much, much lower

It’s true that some microbial bugs in the soil gobble up methane. But this sink has never been shown to come even close to outweighing methane emissions from livestock.

Just as with transport or energy use, greenhouse gas reduction strategies are needed all along the supply chain. As things stand, direct emissions from agriculture are not liable for the carbon price, but landholders are unique in Australia’s emissions trading scheme in that they can, if they choose, create carbon credits to sell on the new market.

More efficient production is certainly part of the solution: healthier animals tend to put on weight quicker and emit less. (This could lead to a kind of ‘rebound effect’ if improved production spells higher stock numbers overall—something worth watching closely.) Changes in feed and other factors can reduce emissions substantially. And, where possible, converting manure into energy (as is being done in some piggeries and dairies now) saves fossil fuels and cuts methane emissions. Of course, setting aside land for bushland restoration or tree crops is a tried and true method of locking up carbon.

As for vegetarianism: it’s a highly unlikely prospect for most, so a bit of a (excuse the pun) red herring. There is, however, every reason to think the meat and livestock industries in affluent countries are smart enough to profitably adapt to more moderate consumption here while satisfying the growing needs of the developing world.

This then is the tricky dilemma we’ve inherited: to reduce the carbon hoofprint of the livestock sector, in a world demanding more and more, without losing the benefits—especially to those most in need. As problems go, it’s a biggy, but there’s no shying away from it. Australian farmers are good at doing more with less and the world needs them now more than ever. It’s one thing to be proud of agriculture’s achievements, but quite another to be over-sensitive to legitimate concerns. Unless farmers squarely face up to the problems, they’ll find it hard to make the most of the solutions.

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