The government has slashed the biogenic methane reduction target. Photo: RNZ / Rebekah Parsons-King
An atmospheric scientist says the new biogenic methane target may need to be reviewed in the future, if the global context changes.
The government has slashed the biogenic methane reduction target from 24 to 47 percent below 2017 levels by 2050, to 14 to 24 percent.
University of Canterbury associate professor Laura Revell was one of five experts on a government-commissioned panel into the new target range.
She said the figures were "consistent with the global context".
"The targets were initially conceived assuming the world was going to meet the ambitions of the Paris Agreement, limiting warming to 1.5 degrees above pre industrial temperatures. Unfortunately, we're not on track to meet that," Revell said.
"Globally, emissions are surging, warming is happening at pace, and given the commitments of other countries, we don't expect that we are going to meet the 1.5 degree target, unless we overshoot and manage to bring emissions back down again. "
However, Revell said the global context could change.
"Were the rest of the world to suddenly make very steep cuts to methane emissions, our methane emissions would, proportionately, contribute more warming.
"So there would be a need to review the target at that point and consider making steeper cuts in the future."
On the new target, Revell said the change in policy would not have "a discernible influence on global warming".
"We won't see emissions skyrocket. Emissions from New Zealand agriculture increased over the 20th century. They've been fairly steady since around the start of the century so what we would expect to see would be some slight declines in emissions going forward but not massive cuts.
"The 14 to 24 percent cuts, which are less ambitious than what was previously in the target, they will still ensure that we are on track with ensuring no additional warming from methane, above and beyond what it was doing in 2017."
The government will legislate the new biogenic methane target by the end of the year.
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