Cow farts: worse than all coal-fired power stations combined

It’s almost a year since Barry Brook, Professor of Climate Change at Adelaide University, posted a piece on his blog about Australia’s most powerful global warming agent. That piece, co-authored with Peter Singer and I, showed that Australia’s livestock cause more warming than all our coal-fired power stations.

It wasn’t a defence of coal, it was a plea for people to understand the role of methane as a potent climate forcing and to understand that cattle methane is no laughing matter.

At that time, news media regularly and wrongly claimed that methane as a greenhouse gas has a warming impact “only” 21 (or 23, or 25) times that of CO2. Even the well read Professor Ross Garnaut showed a stunning ignorance of methane’s true warming impact in his report.

Unfortunately, not much has changed. The world’s media continues to misrepresent the potency of methane and cattle methane continues to prompt cartoons rather than action.

But in an opinion piece in last week’s New Scientist, Kirk Smith, Professor of Global Environmental Health at the University of California in Berkeley, makes a forceful call for methane’s real warming impact to be accurately counted in international agreements. He points out that a tonne of methane contributes 100 times more warming during the first five years of its lifetime as a tonne of CO2, yet under current Kyoto rules, its comparative potency is set at 21. This is because the relative impacts of ALL greenhouse gases are averaged over the same period 100 years, regardless of their atmospheric lifetimes.

This is like applying a blow torch to your leg for 10 seconds but calculating its average temperature as just 48 degrees because that’s what it is when averaged over 20 minutes, with 20 minutes being used because that happens to be some agreed international standard when measuring heat sources applied to legs. The implication being, of course, that a blow torch for 10 seconds and a 48 degree hot water bottle for 20 minutes have the same effect. Some standards have little rational basis, and this particular standard isn’t just dumb but globally and dangerously counter productive. If methane’s warming were properly accounted for, there would be more incentive for reductions.

Any budding Miss Marple investigating the issue would soon realise that climate scientists don’t use this Kyoto factor for methane in their global climate models. They use its true forcing, integrated, if required, over the time span under study. It’s really just economists, bankers, politicians and international climate horse traders, the kind of people who gave us the global financial meltdown, who prefer a wrong but simple number to the truth.

Climate scientists have known about the Kyoto methane bungle for well over a decade with NASA’s chief climate scientist James Hansen remarking on the inappropriateness of the Kyoto factor in a number of papers over the past decade. But changing a poor standardisation decision is like trying to stop a tidal flow with a teaspoon, especially when the constant underestimation of the full impact of livestock methane favours a rich and powerful industry like the global beef industry.

Smith’s article refers to recent modelling showing that methane and black carbon reductions are the quickest way to reduce warming and give the planet a fighting chance of avoiding dangerous climate tipping points. James Hansen worked this out somewhat differently a few years back, but went even further in his 2007 paper on trace gases estimating that while control of CO2 is absolutely necessary to avoid dangerous climate change, it IS NOT sufficient. Even if we quickly and efficiently reduce all CO2 emissions, we are still toast unless we control methane and other trace gases — plus black carbon.

The activities which generate methane and black carbon are many, including livestock production, emissions escaping from coal mining operations (called colorfully “fugitive emissions”), leaky natural gas pipes, rice growing and, for black carbon, inefficient wood stoves and deforestation (we call this “land clearing” or, even more creatively, fodder harvesting when it happens in Australia).

Somewhat synchronously, an editorial in last week’s Nature science journal calls for increased attention on both black carbon and methane. But the world’s most prestigious science journal follows what a study last year in Public Health Nutrition found to be standard practice for news stories when discussing methane … it ignored the single biggest anthropogenic source, livestock. The study looked at 4582 climate change articles between 2005 and 2008 and found that 0.5% mentioned food animal methane emissions. The Nature editorial follows the Fawlty Tower’s climate change rule … Don’t mention the meat .

But while many articles, like Smith’s, list rice production and livestock as sources of methane, their relative contributions are rarely quantified. The Edgar greenhouse gas inventory database has recently been updated with 2005 data and the key anthropogenic methane players are listed in the table below:

As you can see, methane from livestock and its manure is roughly the same as the combined fugitive emissions of all fossil fuels. Rice methane is about 30% of these. Most of the livestock methane is from ruminants and, believe it or not, ruminant meat provides just 1.7% of global calories for that 108 mega tonnes of methane. More than a few of those calories are saturated fat and even the CSIRO’s professional red meat groupies recommend they be thrown out because they cause heart disease and erectile dysfunction … just for starters. But throwing the fat out makes an environmentally destructive industry even worse. A study in New York state in 2007 showed that it takes 75% more land to produce a thousand calories of lean beef than normal beef. Australians and others in the developed world have an exagerated view of the importance of beef and sheep meat in the global food supply, and even in Australia, beef and sheep meat are just 7.6% of apparent consumption. Apparent consumption is a carcase figure which includes waste, the actual amount consumed is even less. We export about two thirds of all beef, so the massive deforestation of Queenland in the 1990s was just a beef subsidy by the environment.

The logical course of action is to quickly phase out global beef production. This would not only make a significant dent in global climate forcings, it would free up a mountain of grain and allow reafforestation on a massive scale. The planet’s 900 million malnourished people who cannot currently outbid cattle for grain would at last have a fighting chance. Rice on the other hand provides 19% of global calories for its 34 megatonnes. Rice yields are typically 10 tonnes per hectare, about 5 times that of cereals like wheat, so cutbacks to rice production would be difficult or impossible.

A study covered in New Scientist earlier in the year estimated that the cost of climate mitigation could be reduced by $20 trillion dollars by sharply reducing red meat (including pork) consumption. Reductions in total meat production have been recommended by the head of the IPCC, Rajendra Pachauri, but with the emphasis on trading as the tool of choice for reducing emissions, and with the Kyoto rules crippled by the methane factor blunder, any emissions trading strategy will be tackling methane with both hands tied behind its back.

It’s high time Kyoto’s methane factor mistake was fixed. Methane is far more potent than the figure of 21 or 25 that is consistently cited. A factor of 72 would be a reasonable compromise between accuracy and simplicity and would help in driving the changes required to reduce fugitive emissions and cattle populations.

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Peter Fray
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