Has MP made a ‘Methane Mistake’?

Greenhouse gases such as methane and nitrous oxide caused by the agricultural sector, by belching livestock and fertilisers, are thought to produce about half of all greenhouse gas emissions in New Zealand.

So why did Kaiko¯ura MP Stuart Smith take to Facebook last month to declare ‘‘Agriculture is NOT the major source of NZ’S greenhouse gas emissions’’, refuting the stance of the Ministry for the Environment, Landcare Research, and the New Zealand Agricultural Greenhouse Gas Research Centre.

Smith’s post was accompanied by a video, ‘The Methane Mistake’, produced by former dairy farmer and Pastural Farming Climate Research Inc founder Robin Grieve.

However, Smith, a National Party MP, said he was not 100 per cent sure the video was ‘‘scientifically accurate’’. The video argued that methane was a part of a natural cycle and wasn’t contributing to warming the planet.

Smith said a friend, a university professor, told him methane was not an issue and should be measured in a different way, as the current method overstated its impact.

International greenhouse gas reporting used a metric called Global Warming Potentials (GWP) which assumed carbon dioxide had a value of 1, over 100 years, with other gases having a value expressed in so-called ‘carbon dioxide equivalents’.

Methane had a value of 25, or 25 times ‘worse’ than carbon dioxide. Nitrous oxide had a value of 298.

New Zealand Agricultural Greenhouse Gas Research Centre director Dr Harry Clark said more than 50 per cent of New Zealand’s carbon dioxide equivalent emissions came from agriculture, when carbon dioxide emissions from ‘‘agricultural processing, transport etc’’ were included.

Smith last year called for agricultural emissions to be exempt from the Emissions Trading Scheme, which is aimed at minimising and offsetting emissions through planting forestry and charging for pollution.

Smith believed the country did not have to do ‘‘anything radical’’ around methane control, as any necessary reductions would come about through regular farming efficiencies.

However, Clark said the video shared on Smith’s Facebook page was misleading.

‘‘There is a fallacy that stabilising emissions makes the methane problem go away. It doesn’t since all emissions of methane warm the atmosphere more than if we hadn’t emitted them. Current emissions might warm the atmosphere more or less compared with previous emissions but all emissions warm the atmosphere,’’ Clark said.

A report prepared by Dr Andy Reisinger of the New Zealand Agricultural Greenhouse Gas Research Centre, written for the Parliamentary Commissioner for the Environment, showed that to stabilise the warming coming from New Zealand’s methane emissions would require a 10 to 20 per cent cut in methane emissions.

Clark said a 20 to 30 per cent cut in methane emissions was required to stabilise warming to the 1990 level.

Smith said on Monday methane was not the issue many people believe it to be and it was not the issue New Zealand should be focusing on.

‘‘CO2 is what the government should be focused on,’’ he said. ‘‘Efficiency in the rural sector has gone up. New Zealand is a very efficient producer of animal products.’’