[permaculture] So what do you really think about long term climate change due to pollution-related global warming

Toby Hemenway toby at patternliteracy.com
Tue Mar 27 10:22:17 EDT 2007

Looking again at that article on methane and global warming--

I don't like the way this guy plays fast and loose with numbers.

>With methane emissions causing nearly half of the planet's
>human-induced warming,"

The other sources I find say methane causes about 20% of the anthropogenic
effect, and CO2 is 60%. So he's really high-grading the data. I'm a big
believer in the reality of anthropogenic warming, but distorting the facts
will weaken our case.

> the number one source of methane worldwide is animal agriculture.17

This is a either wrong or, being charitable, just sloppy writing. Plants
produce 10-30% of all methane and are the largest source. About 30% of the
atmosphere's methane may come from human sources, the author's footnotes say
(estimates range from 10-30%, and of course he chooses the highest estimate,
never an honest strategy). Animals produce about about 15-30% of
anthropogenic methane (he says 32%, again using the highest estimate
available). Taking 32% of 30% means livestock produce, at most, about 9% of
global methane, and probably less. Livestock may be the largest single
source of _anthropogenic_ methane, but that's not what he says. He says "the
number one source," period, which is not true. In truth, livestock are a
pretty small source compared to natural ones.

So if all humans went vegetarian, the most we would see is a 9% drop in
methane. Of course, all that abandoned pasture once used for livestock would
probably start growing deer and bison and wildebeest, replacing some of the
methane. If vegetarianism is the "most effective tool" then we're in
trouble. That's the danger of starting with ideology and then sifting the
data to support it. (I am assuming the author is a vegetarian. And a
disclaimer: I eat very little meat, maybe 2-3x a week. I've got no beef with
vegetarians, just with zealots)

But, my research has given me a new worry! Plants produce 10-30% of all
atmospheric methane (source: http://www.physorg.com/news9792.html )
So if plants are a much larger source of methane than livestock, then the
"magic bullet" mentality says we should stop growing plants. Kill all the
green stuff to save the Earth!

I don't see that he's offering a real solution, even in the unlikely event
that the average person would voluntarily consider giving up meat.


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