[Rob_D]

Good point about fertiliser Sven, be interesting how much that's been considered in this. You maybe right, but it's not easy to say.

- more than half the US nitrogen-based fertlizer goes on pasture according to Wikipedia. I don't know that much of the US corn & wheat industries use much manure at all? If they get rid of these animals, they could double the area of arable for the same amount of fertilizer which would produce far more food than they need. In fact they could probably reduce the arable farming, not even have to increase it. It's not true of most countries, but the US could probably reduce fertilizer use = more CO2 saved producing it. (am I wrong here?) I suspect it might apply somewhat to Britain too, but not to the same extent.

- there are renewable sources of fertiliser like algae.

- it is possible to use renewable energy like solar, hydro or wind power to produce the fertiliser - you don't need such a continuity of supply like for most power uses.

- only ruminents burp very much methane right? So we can still have chicken and pigs to produce manure. and eggs too ;-)

- reduced pressure on land use would mean
less need for intensive arable = much reduced fertiliser demand
much longer crop rotations = less need for fertiliser
greater areas for carbon-sinking forests

- cattle and other ruminents are also significant factor in desertification, which is also contributing to global climate change isn't it?

- the western developed countries are the worst culprits in GW by far. Most inhabitants of these countries, including Britain, many really could do with a reduction in calories! In those countries where people don't get enough, they don't often get much meat in any case. Of those 1.3 billion cows, most are consumed by those who don't need it!

Living in a predominantly intensive arable area, I really do accept your point about biodiversity though. I much prefer mixed farmland for wildlife. Perhaps non-intensive arable is not so bad though - we just have so little left.