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Climate Change and the Recent Increase in Livestock

March 27, 2010

LCC and Stephen Walsh discussed on March 16, March 25, March 27, and March 29

Stephen Walsh’s third objection to Livestock and Climate Change (LCC) is that the authors of LCC have mishandled the 12% increase in livestock between 2002 and 2009.  Walsh states:

"A further incorrect assumption is that the impact of livestock calculated by the FAO can be scaled up based on a 12% increase in the kilograms of livestock foods produced between 2002 and 2009 while other emission sources can be treated as having remained constant."

Walsh gives three reasons for this: (1) different kinds of livestock have different climate change effects, (2) even the same kind of livestock can have different effects, and (3) non-livestock emissions also increased from 2002 to 2009.  

It’s true that different kinds of livestock have different climate change effects.  The most obvious difference concerns methane and ruminant animals; cattle have more of a methane effect than chickens.  But has animal agriculture changed that much in the past decade?  

According to my set of Vital Signs issued by WorldWatch Institute, in 2001 there was 56.87 million tons of beef produced out of a total of 237 million tons of meat, about 24% of the total. In 2008, these figures were 65 million tons of beef and 280 million tons total, so beef was about 23% of the total (although the Vital Signs 2010 pie chart on page 60 gives a figure of 24%). While it is true that beef consumption as a proportion of total meat consumption has declined since the 1970's, in recent years it seems to have leveled off and in fact the percentage has barely changed at all between 2001 and 2008.   

Of course, even the same cow may generate a very different set of GHG emissions depending on the circumstances. Paradoxically, the otherwise environmentally unfriendly (and cruel) factory farm system will probably generate fewer GHG emissions because grass-fed beef creates more methane than grain-fed beef. Walsh is rightly concerned about this — he fears that an "environmentally correct" livestock industry might actually be worse for the animals than the present system.

I am inclined to agree with Walsh that to really get detailed and accurate figures, you would need to go into considerably more detail. On the other hand, to a casual observer it doesn’t seem that livestock agriculture has changed that much in the last decade. It’s still the same old factory farming system. If livestock increased by 12%, in all likelihood their GHG emissions also increased by 12%. Moreover, to the extent that the per-animal GHG effect has changed, it could just as easily be a change for the worse (environmentally speaking) as a change for the better. Perhaps a lot of the increase in cattle has been in the Amazon region, rather than in U. S. feedlots, for example.

The third reason, that non-livestock emissions has also increased from 2002 to 2009, seems to be the most valid.  This relates to the percentage of greenhouse gas ( GHG) emissions from livestock (as related to total emissions), not the absolute amount.  Isn’t it pretty clear that non-livestock GHG emissions have been increasing, with more coal plants being built everywhere?  So would the relative percentage of GHG emissions from livestock necessarily have gone up at all between 2002 and 2009?

The impact of this point is marginal. In the first place the 12% increase in livestock did not raise livestock’s percentage of GHG emissions by 12% or 6%, it only adds 4%.  So non-livestock emissions may have already been factored in to a certain extent (it isn’t clear to me).

If Walsh is right, this means that the total percentage of GHG emissions from livestock is not 51%, it’s only 47%. But the LCC authors now have a trump card: the actual number of livestock now cited by the FAO — 56 billion — is more than twice the FAO’s previous estimate of 21.7 billion, and is 10% more than even the LCC authors previously estimated. In fact, this figure of 56 billion livestock is now in Vital Signs 2010 put out by WorldWatch.

This generous underestimate seems to cover a multitude of other sins.  By themselves, these objections might carry some weight concerning the way the article was written, but they do not refute the general conclusions of LCC, that livestock GHG emissions are a lot more than we thought they were.