They said this morning that CO2 emissions in France were really not as much of a problem (our electricity is Nuclear) as Methane released by farm animals and even worse (surprise this, as I have never heard of it) N20 released as a by-product of Nitrogen fertiliser on crops. Di-Nitrogen Oxide is 300 times worse as a greenhouse gas than Carbon Dioxide. So stopping eating meat might not do much?
Yes, Nitrous Oxide is the third of the agricultural bad boys, with carbon dioxide and methane. Nitrous oxide is given off by artificial fertilisers, but also to a lesser extent by dung. In the case of dung, it tends to be washed into the soil on grasslands and reused within that local ecosystem, whereas nitrous oxide is washed into river systems causing a whole load of other problems. Both give different amounts of nitrous oxide into the atmosphere as well.
There are several other gases which are damaging to the atmosphere, such as the fluro carbons. The early awareness of damage to our world climate came with the release of fluro carbons, as used in fridges and other applications as a coolant, causing a giant hole in the ozone layer. That caused a whole lot of derision from those who knew nothing but thought they knew it all, and set the scene for 'climate change deniers'.
Incidentally I am horrified to discover that although we all dutifully send our old fridges and freezers to be recycled, and the gases removed and reused, that is not in fact always happening. There are pictures of huge piles of dumped fridges and freezers with no recycling and reclamation, because councils simply don't know how to deal with them.