A distinguished climate change scientist will be in Whangārei talking about sheep burping, cows farting, the effects of methane production and its place in a zero carbon future.

Professor Myles Allen, from the University of Oxford, England, has led a number of assessments for the International Panel for Climate Change (IPCC) since 2001.

His research focuses on how human and natural influences on climate contribute to observed climate change and risks of extreme weather, and in quantifying their implications for long-range climate forecasts.

While Allen's recommendations about reaching zero carbon and how best to account for methane production are of interest to New Zealand's agricultural and business sectors, others find his views on climate change controversial.

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As for ruminants' digestive activity, Allen believes it is not a huge contributor to the bigger sphere of climate-warming gases.

''New Zealand's Zero Carbon Act could make it one of the first advanced economies in the world to commit itself to net zero emissions — and the first with such a large agricultural sector.

''The big picture could not be simpler. Carbon dioxide emissions accumulate in the climate system, like lead in the bloodstream. Stopping global warming requires net carbon dioxide emissions to be reduced to zero, permanently,'' he wrote for an address at Auckland University.

''Decisions about other warming gases, like methane, could make a few tenths of a degree difference to the peak warming level reached, but they don't change that all-important fact.''

According to Landcare figures the release of methane gas from ruminant livestock (sheep and cattle) amounts to almost a third of New Zealand's greenhouse gas emissions, and it is the largest contributor.

Allen said a successful pathway to net zero required clarity, fairness and transparency.

''I will argue that the simplest way of designing fairness and transparency into the Zero Carbon Act is to focus on the long-term temperature goal set out in the Paris Climate Agreement. This means treating all sectors equally in terms of their impact on global temperature.

''Traditional farmers who are not contributing to ongoing global warming would not be penalised as if they are, while an agribusiness initiative that would cause a large increase in methane emissions, with a correspondingly disproportionate impact on global temperature, would be treated accordingly.''

He is giving a public lecture as part of the Tai Tokerau Series at Whangārei Library on Thursday, March 21.