How does methane contribute to global warming – Expert Reaction

New research released by the Parliamentary Commissioner for the Environment Simon Upton highlights the impact methane from New Zealand’s livestock has on global warming.

Authored by Dr Andy Reisinger, from the New Zealand Agricultural Greenhouse Gas Research Centre, the report indicates that methane emissions from livestock would need to be reduced by at least 10-22 per cent below 2015 levels by 2050 to ensure no additional warming beyond current levels.

Upton said the research was being released to inform the current debate about how different greenhouse gases should be treated under the proposed Zero Carbon Bill. “It shows that holding New Zealand’s methane emissions steady at current levels would not be enough to avoid additional global warming.”

The SMC gathered expert reaction on the research.

Professor Dave Frame, School of Geography, Environment and Earth Sciences, Victoria University of Wellington, comments:

“There are three main scientific points that readers should take away. One is that you could keep around 80-90% of NZ’s current methane emissions and not cause further warming by 2050. That’s pretty consistent with ‘Option 2’ as set out in the recent MfE consultation document, though the report is careful not to say so. A second point is an endorsement of the GWP approach a group of us suggested earlier in the year. A third point, not highlighted but certainly clear from the results, is that reductions in methane emissions at faster rates than about 0.3% per year lead to a cooling of the climate.

“Perhaps the best bits of the report are in the Appendix, which shows that CO2 emissions are the main determinant of New Zealand’s future warming: if emissions of CO2 and methane are both held constant, then our future warming legacy is dominated by CO2, while if we reduce act strongly on CO2 we can limit that warming very substantially. In effect, methane dominates our historical warming legacy, but CO2 will dominate our future warming legacy unless we enact strong policies on fossil fuel emissions. We should not take that action for granted. It should be the overwhelming focus of climate policy.”