[thedoc (OP)]

emily Valentine asked the Naked Scientists:
   I heard your program last week and your panel said that what was best for the planet ecologically is to eat less meat. I disagree.
Population control and having no children is the best thing you can do to reduce the stress on the environment.
As western societies, we are critical of the Chinese one child policy, yet I wonder where the world would be now without it?  How many more Chinese would there be now if the policy had not existed? How big would their population be if they had had children at the same rate as India? Thailand? Brazil?  UK? Or Canada?
Population control is never mentioned when discussing sustainability of the Earth, yet it is vital and practiced by many people and societies.
What do you think?

[alancalverd]

Human breath constitutes about 10% of all anthropogenic carbon dioxide. Animal breath acounts for nearly 25%. So if you believe that CO2 is responsible for climate change, it is actually more effective to change our diet than to limit our population. However if you don't limit the population, both numbers will increase anyway.

Since it costs nothing to do either, we should of course do both. The benefits would be realised immediately

[chris]

Interesting points.

But what mass of CO2 does a human - or a cow - breathe out in a year? And what fraction is this of the 35 billion tonnes of man-made carbon dioxide emitted annually?

[alancalverd]

10% and 25% respectively.

Practically all "artificial" energy comes from burning hydrocarbons  and carbohydrates. The average artificial power consumption is about 1500W per capita.

All warmblooded animals run at about 2 W/kg by oxidising hydrocarbons and carbohydrates. Humans produce about 150W per capita , and farm animals about 2.5 times that amount per human.