This is my comment on an interesting post by Tara Garnet on her FRCN blog, Has veganism become a dirty word? There are different views on the effects of methane on climate.
Comment on ‘Has veganism become a dirty word?’ by Geoff Beacon
Actually, methane’s not the problem we thought it was; methane’s temporary, actually methane’s natural.
Tara, this seems to be the view of Myles Allen and Richard Millar of your Oxford Martin School. As I understand it, their picture is this:
Emissions of methane heat the Earth’s surface for a decade or so before decaying. The rise in the Earth’s temperature causes net heat emissions to space. The long term effect on temperature is small. If keeping Earth’s temperature below a certain threshold is a target, then unless the target is likely in the next decade or so the temporary rise in surface temperature is not important.
There are others that disagree.
For example, Xu and Ramanathan or Collins et al. Again, as I understand, they believe it would be wise to reduce immediate warming by cutting methane emissions (as well as other actions to cut longer lived gases especially carbon dioxide). This would lessen the chances of short-term heating setting off feedback mechanisms, some of which may be difficult to shut down. In the short term, only a proportion of the extra heat is radiated to space. Some heats the deeper oceans and some melts ice on land and sea. These effects do not raise surface temperature but have longer term climatic effects.
Do Millar and Allen concentrate too heavily on the predictions of average surface temperature rise from computer models that have serious missing feedbacks?
The average temperature of the Earth is not the only worrying parameter of Earth’s climate. Ocean heat content, the remaining volume of ice, the waviness of the jet stream and the distribution of temperature rise are others.
As an amateur, I lean towards Xu, Ramanathan and Collins but I wish I didn’t have to look up and try to understand academic papers to tell my friends and others that beef and dairy is very bad for the climate because of the methane that cattle (and sheep) emit.
Can something be done to make this debate more understandable?
Video or a presentation by Myles Allen: Methane is discussed after 29 minutes.
Video of a presentation by Peter Cox: Methane reduction possibilities after 11 minutes.