Two in three paddocks' worth of pine needed

Friday 14 Oct 2022

Rivers bursting their banks, flash floods and more intense cyclones – how climate change is making floods more extreme. We'll need more than a few shelter belts and riverside trees to offset farming methane. This is the conclusion of New Zealand’s Parliamentary Commissioner for the Environment Simon Upton.

His conclusions (and accompanying calculations) found up to 5.8 million hectares of pine would be required to achieve methane-neutrality. That’s the equivalent of two out of every three paddocks in the country covered by plantation forest – and would be in addition to the minimum 24% methane cut required by the Zero Carbon Act.

Upton said the results of his report showed New Zealand “cannot simply plant our way out of this problem, just as we can’t plant our way out of burning fossil fuels”.

The commissioner calculated how many pine trees would be required to go beyond the 2050 requirement to cut biological methane by between 24 and 47%. Introducing the report, Upton said this target was approved by a near-unanimous vote in Parliament, and he was not recommending any changes.

“This is not about planting trees instead of reducing agricultural emissions.” But Upton wondered whether new forests could help meet the methane target. Because it’s short-lived, methane has a different effect on global temperatures compared to long-lasting gases such as carbon dioxide.

Domestic livestock is producing roughly constant amounts of methane each year, the report said. (Landfills also produce methane, but this contribution isn’t covered in the report.) The warming effect of methane emissions is powerful in the beginning, but then tapers off over time – though it doesn’t flat line.

According to Upton’s report, harvested pine forests produce an almost mirror image of this pattern: they absorb a lot of carbon dioxide in their early years – and therefore quickly have a cooling effect on the atmosphere. In later years, this tapers off. The atmospheric heating caused by stable methane emissions can be offset by the impact of harvested pine forests as these absorb carbon dioxide and store it as wood, the report found.

Based on this alignment, 0.6ha of pine plantation forest would offset the emissions of each dairy cow. Each beef cattle would require 0.4ha, deer 0.2ha and sheep 0.08ha. To offset total livestock methane 10% below national target, 770,000ha of pine forest would be required by 2050.

More >>.

Keith Woodford, a Principal Consultant at AgriFood Systems in this article presents and discusses some of the big issues that Simon Upton raises exploring the possibilities of using carbon sequestration from forestry to offset methane emissions.

Source: Stuff

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