Professor David Frame

Greenpeace and Greens co-leader James Shaw have dramatically fallen out over climate change policy.

Shaw told Parliament last week that New Zealand did not need fewer cows for agriculture to meet our emissions reduction targets.

Greenpeace violently disagrees.

“We are in a climate emergency, and intensive dairy is New Zealand’s biggest climate polluter, so it’s alarming to hear our Minister for Climate Change deny that we need fewer cows,” said Greenpeace Programme Director Niamh O’Flynn.

The Greenpeace website said the organisation had been increasingly critical of Shaw  in recent months, “but things have escalated following Shaw’s Parliamentary question time denial of the need to reduce cow numbers.”

The organisation now has a petition calling for the New Zealand dairy herd to be halved.

But yesterday at Parliament, a Select Committee chaired by Shaw’s Greens colleague, Eugenie Sage, heard a more nuanced story about the agricultural greenhouse gas, methane, from a panel of scientists put together by the Climate Change Commission.

Central to the scientists’ comments was the very different warming effect of methane compared with Carbon Dioxide.

Simply, carbon dioxide lasts in the atmosphere much longer and whilst methane has a more powerful immediate warming effect, it begins to decay after about ten years.,

Professor Dave Frame, the  Director of the New Zealand Climate Change Research Institute at the Victoria University of Wellington, said the average lifetime of a methane molecule was about a decade, whereas the CO2 molecule lasted much longer.

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“Around about a third to a quarter of the CO2 you emit from the tailpipe of your Ford Ranger or whatever is still in the atmosphere in a thousand years’ time, roughly speaking,” he said.

“It’s a long-lived gas, and that is that is overwhelmingly what your climate legacy will be; your CO2 after your life, because the short-lived pollutants you emit will break down over the following decades.”

NIWA Atmospheric and Oceanic scientist Sara Mikaloff-Fletcher, told the Committee that though methane was a short-lived gas, cutting it would have a much bigger impact in the short term than cutting an equivalent amount of carbon dioxide because methane’s immediate impact on warming was 85 times greater than C02.

“It’s worth considering that these scenarios that our target (net-zero by 2050) is based on all assume agricultural emissions reductions,” she said.

“So globally, if we choose not to reduce agricultural emissions, that means we must then reduce carbon dioxide that much faster in order to compensate.

“So these two targets are really interconnected.”

That points to the real problem in New Zealand which is our failure so far to make meaningful cuts in C02. That is why making bigger cuts to methane becomes an option.

“I sometimes think when we have conversations about  (limiting the global temperature increase) to one and a half degrees in New Zealand, we lose sight of the fact that it is far from a given that we’re going to,” said Frame.

“We have to do a huge amount on CO2, and it has to go all the way to zero.

“And the short-lived pollutants don’t.”

It is the difference between the effect of the two gases which has seen Frame in recent years become a strong advocate of New Zealand’s split gas approach and a critic of New Zealand’s climate change diplomats for not taking a more assertive approach internationally to those countries, such as the United Kingdom, who do not agree with splitting the gases.

“New Zealand is actually doing some great stuff on having different targets and on working on He Waka Heke Noa, where we are looking to treat the gases separately and that all seems to me to be completely reasonable,” he said.

“And I don’t think we should get shouted down by a lot of people overseas who don’t necessarily have as good a handle on this.”

New Zealand’s Zero Carbon Act requires that the dairy industry reduce its methane emissions by 10 per cent by 2030 and by 24 – 50 per cent by 2050.

Mikaloff-Fletcher questioned those targets.

“Essentially, the agricultural methane emissions that became our targets were plucked directly from the global agricultural methane emission drop that’s required.

“they are from the middle batch of these scenarios from this report. (The UN International Panel on Climate Change 6th Report),” she said.

“So are these the right targets for Aotearoa- New Zealand?

“That’s not really a question for me to answer as a scientist.

 “That’s a political question.”

She said the targets didn’t take into account the special challenges we might face as New Zealanders or the opportunities that we had as New Zealanders.

“Nor do they consider the idea of differentiated responsibilities that some nations that have contributed more to historical emissions and are in a better financial position might also be expected to reduce emissions more than other countries.”

She said the country knew it must reduce carbon dioxide emissions to net-zero by 2050 if it wanted to limit warming to 1.5 degrees C.

“And if we choose a lesser target, such as two degrees C, it’s still a rapid reduction to zero of carbon dioxide emissions that will still be required.

“But with methane, we have some room to manoeuvre.

“It’s possible to achieve this with smaller agricultural methane emissions reductions than what set out in these reports nationally.

“But it’s worth considering that these scenarios that our target is based on, they all assume agricultural emissions reductions.

“So globally, if we choose not to reduce agricultural emissions, that means we must then reduce carbon dioxide that much faster in order to compensate. So these two targets are really interconnected.

“We’ll have to move the timetable forward on carbon dioxide if we choose not to reduce methane as much.”

That is the core of New Zealand’s climate change choices. Methane and Carbon Dioxide are like a seesaw; if one goes up, the other must go down.

The Select Committee was not only chaired by one of the Greens’ key environmental spokespeople but also included National’s Climate Change spokesperson, Scott Simpson and ACT’s agriculture spokesperson, Mark Cameron.

The hearing is part of what is becoming a rapidly growing climate debate in the leadup to the announcement next month of the country’s Emissions Reduction Plan, which will set out what the country has to do to meet the carbon budgets published last year by the Climate Change Commission.

Ironically, the agricultural sector is the only one at this stage with specific targets it must meet.

But that will change as the entire economy gets its climate change map with the publication of the plan.