Posted 1 November 2009
The Scientific Alliance comments on the odd proposal in the Times of London by Lord Nicholas Stern that humans should give up eating meat to save the planet from global warming.
THE SCIENTIFIC ALLIANCE (UK)
Can vegetarians save
The Times this week devoted three pages to an interview with
Lord Stern (of the eponymous
report): a double page spread with his pre-Copenhagen thoughts and a front page
headlined 'Climate chief: give up meat to save the planet'. Not surprisingly,
this sparked considerable debate over the following few days. The noble lord
himself said that his remarks had been taken out of context, that he was
pointing out the carbon intensity of livestock farming rather than suggesting a
wholesale change of diet. No matter, the story had been written, and the debate
This quite neatly encapsulates a whole range of important
questions. What kind of diet should we be eating? Should we be raising animals
for food? Could changing farming practices reduce greenhouse gas emissions
significantly? If so, does it matter?
On the diet question, this just stirs up the usual pro- and
anti-vegetarianism arguments once more. Ignoring for the moment any ethical or
moral considerations, we have to accept that humans are natural omnivores. We
have teeth which can cope with pretty much any kind of food. Carnivores such as
dogs and cats have no teeth suitable for chewing, herbivores such as cows and
horses cannot physically cope with meat. We can do both.
Hunter/gatherer societies which existed before farming was
established would have had a diet high in animal protein. Archaeological
evidence suggests that they may have been better nourished than many later
peasant farmers who subsisted primarily on their crops. This does not mean that
a vegetarian diet is bad, just that it is easier to get enough high-quality
protein and many micronutrients from animal sources. Strict vegetarians may
have to supplement their diet with micronutrients (such as B Vitamins) to avoid
deficiency diseases, and vegans must be even more careful to balance their
Experience suggests that vegetarian societies are the
exception. As people can afford it, meat eating tends to increase, a trend
which is now very evident in China .
Most people like meat, although they often consume more than they need: a large
proportion of calories can easily come from carbohydrates rather than protein.
But Lord Stern 's
point was that a reduction in meat consumption would have a beneficial environmental
effect. Each kilo of meat requires several kilos of animal feed to produce it,
and animals are themselves a significant source of methane emissions. Follow-up
letters to the editor gave two responses to this from very different sources.
First, Clare Oxborrow
of Friends of the Earth wrote in support not of vegetarianism, but of
'planet-friendly farms and home-grown animal feeds' to provide 'less but better
meat and dairy'. This was essentially an attack on the present system of
intensive agriculture, dependent on large imports of soy protein. Consumption
of animal products would certainly go down in this scenario, since they would
become much more expensive.
This plea for more extensive farming, although it did not
use the word 'organic', is the approach called for by the Soil Association and
others in the organic farming movement. The true believers argue for conversion
of global agriculture to their principles, despite clear evidence that the
sector remains a niche even in prosperous Europe . When presented
with the evidence that farming without synthetic fertilizers could only feed
perhaps 4 billion people, the response tends to be that we should all become
vegetarians, when the available food would in fact be sufficient.
What this argument ignores is that organic farming is
essentially a closed-loop system, relying heavily on animal manure as a source
of nitrogen. Livestock numbers would have to increase significantly, and the
corollary of this is that meat and dairy produce would be an integral part of a
global organic diet unless farm animals were to be simply a source of fixed
The alternative, if the diet was to be vegetarian, would be
the use of green manures, crops of clover and other legumes to be ploughed in
to provide soil fertility. But this would mean that one-third or more of
farmland would be unproductive in any season, to allow for the growth of
legumes. Whichever way you look at it, organic farming does not add up, with or
without meat in the diet.
The second letter to the Times was from Ian
Crute , of the Agriculture and Horticulture
Development Board. His point is that producing meat is part of the overall
balance of agriculture, and eliminating it from the mix would make only a
marginal difference to emissions of greenhouse gases. Livestock grazes on the
large proportion of land which is best suited to growing grass and would not be
productive arable land, and also consumes large quantities of the by-products
of human food production: soy and rape meal and citrus and sugar-beet pulp, for
Estimating the greenhouse gas emissions from farming is very
complex, and not altogether helpful. Farm animals are undoubtedly a significant
source of methane, but this is outweighed by wild animals (and termites, which
produce huge amounts). And much of the methane comes from marshland and paddy
fields, not animals.
We hear that methane has a much higher warming effect than
carbon dioxide. But this is partly because there is much less of it in the
atmosphere, so each addition has a much greater relative effect. Overall,
methane makes a much smaller contribution to the greenhouse effect than CO2,
and this in turn is outweighed by the effect of water vapour.
We should also not forget that, although concerns are often
expressed about methane emissions, the concentration in the atmosphere has been
stable or declining in recent years. This is just one more facet of the
enormously complex web of factors which have an influence on our climate. It is
important that politicians recognise how much we simply do not know, rather
than assume we know enough to make far-reaching decisions which will affect the
lives of all of us.
But that is the trajectory we are on at present, with all
eyes focussed on the summit meeting in Copenhagen
in December. One of Lord Stern 's
key messages (although this was not clear from the front page story) was that President
Obama should be present in Copenhagen
and use his prestige and influence to help achieve a post-Kyoto climate deal.
Given his lack of success in securing the 2016 Olympic games for Chicago
when he last visited the Danish capital, he may think otherwise.
Vegetarianism is not going to save the world, and neither
will anything agreed in Copenhagen ,
whatever fine words are used. If there truly are dangers we face from changes
to the climate, it is best that we understand them properly before taking
expensive, perhaps unnecessary, and almost certainly ineffective, action.
The Scientific Alliance
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