Professor Barry McMullin:

We must distinguish between the long-term temperature effect, which would be relatively small - by "long-term", I mean hundreds to thousands of years - and the short-term effect, which is within this century, say the next 30 to 60 years. Hopefully, we will succeed in peaking global temperature within the next 30 years. We can see what is already happening. If we do not manage to peak temperature within the next 30 years, we will probably be in a global situation that is beyond any prospect of human adaptation. These few decades ahead are critical. The impact of and contribution from methane to maintaining global temperature over these next three to six decades are absolutely critical.

Any reduction in methane flow now will manifest itself exactly in that timescale. Therefore, to limit the peak temperature and keep it at a level that will give us some prospect of surviving, managing or adapting to, then managing down the methane burden is critical. All the models run by the IPCC that meet the 1.5°C goal rely on methane emissions from all sources, including fossil fuels, ruminant agriculture, landfill, rice paddies, etc., reducing substantially in the coming decades. If not, we will not limit the peak temperature.