Just holding methane not enough

AUCKLAND: Keeping New Zealand’s methane emissions to today’s levels will not be enough to prevent further global warming, new modelling has shown.

Research released yesterday by Parliamentary Commissioner for the Environment Simon Upton comes amid debate around how — or whether — the greenhouse gas should be covered by the Government’s proposed Zero Carbon Act.

The three options on the table are forcing carbon dioxide (CO2) and nitrous oxide (N2O) down to zero by 2050; doing this while also stabilising shorterlived gases like methane; or requiring all gases to be reduced to net zero by the midcentury deadline.

But the new modelling, led by agricultural greenhouse gas expert Dr Andy Reisinger, suggested simply holding the line on current livestock emissions would not avert more warming.

‘‘It shows that holding New Zealand’s methane emissions steady at current levels would not be enough to avoid additional global warming,’’ Mr Upton said.

The work indicated that, to ensure methane from livestock contributed no additional warming beyond current levels, emissions would need to be cut by at least 10% to 22% below 2016 levels by 2050, with further reductions by 2100.

Mr Upton said he was not backing a specific climate target or approach for slashing livestock methane or other agricultural greenhouse gas emissions, but wanted to see an evidencebased debate on how best to approach it.

‘‘I hope this new work will help promote debate on reducing methane emissions that is grounded firmly in science.’’