GLOBAL WARMING: COWS OR CARS? - MEAT: A Benign Extravagance - page 205

It is also worth comparing the methane toll of milk against that of cars. At 25 grams of
methane per kilo of milk, someone consuming a pint of milk a day would be emitting about
130 kg of CO 2 eq a year. This is about three per cent of the 3.9 tonnes emitted by driving
10,000 miles per year in a small car averaging 37 miles per gallon. 40 Since about five per
cent of total emissions from fossil fuels are methane, the car driver is arguably respons-
ible for as much methane as the milk drinker, quite apart from emitting 30 times as much
CO 2 . 41
A more significant concern for anyone proposing to reduce or eliminate the global
cattle herd is the extent to which it would be replaced by methane-emitting wild animals.
Whenever domestic animals are removed from grassland, other species try to move in. In
Scotland, for example, when sheep are removed, deer take over: if you want trees to grow
you need a deer fence not a sheep fence. 42 In wet areas like the UK we could, if we wanted,
turn most of what is presently cow and sheep pasture into woodland, by fencing out wild
animals. But large areas of the world consist of natural grasslands which are too dry to
maintain tree cover and it is hard to imagine anything else replacing cattle or sheep, except
their wild predecessors.
When Tanzania's Serengeti National Park was established in 1951, resident Maasai
tribes were removed from the area, together with their cattle herds which had already be-
come greatly depleted by rinderpest and tsetse fly. Since then the population of wild an-
imals, particularly ruminants, has multiplied: in the early 1960s there were an estimated
250,000 wildebeest in the park; by 1979 there were 720,000, and in all about two million
large ruminants, including buffalo, gazelles and giraffe, plus 240,000 zebra. Using the 1979
census, the climate scientist PJ Crutzen calculated that their annual methane emissions
totalled 19,500 tonnes. 43 By global standards this was a tiny amount - the total amount of
methane emitted by domestic animals at the time, 74 million tonnes, was 3750 times as
large.
However, the Serengeti is small by global standards, 14,700 sq km, almost the same size
as Northern Ireland: you could fit 2,600 Serengetis into the 38 million square kilometres of
the world's land which the FAO classes as grassland. 44 If all this land were reclaimed by
wild ruminants at the same concentrations as in Serengeti in 1979, they would emit 52 mil-
lion tonnes of methane, or about five eighths the amount which domestic livestock are now
presumed to be emitting. 45 Since Crutzen carried out his study, the herds of wildebeest are
reported to have doubled again in size to 1.5 million. 46 The current wildebeest population
in Serengeti suggests that some of the world's grasslands might end up being so heavily
stocked with wildlife that they produce as much methane as they currently do with domest-
ic animals.