A new report says New Zealand should focus on the warming impact of gases, rather than total emissions, when trying to reach our climate goals.
New Zealand's agricultural sector commissioned an independent report and has submitted it to the Climate Change Commission, which is set to review our methane reduction targets next year.
Waikato sheep and bull farmer Phil Weir has planted 40,000 native trees at the foot of Mt Pirongia. But "at the moment none of our plantings are recognised or entered into an ETS (Emissions Trading Scheme), but our hope is that we've done the right thing and one day they may be," he explained.
But farmers don't dispute they're responsible for nearly half of New Zealand's greenhouse gas emissions. Federated Farmers national president Wayne Lanford said what they aren't responsible for is "half the warming".
The new report, commissioned by Federated Farmers, Dairy NZ and Beef and Lamb NZ, shows that. Since 1990, farming has been responsible for 49 percent of total emissions but, in that time, the sector has been responsible for just 37 percent of warming.
"What the report is saying is for that for methane to cause no further warming in the New Zealand context from 2020 we need a reduction of 15 per cent by 2050," Beef & Lamb chair Kate Acland said. But Dairy NZ chair Jim van der Poel said farmers are being asked to do much more.
"The current target is 24-47 percent," he said "If farmers are asked to do that then it's huge."
At the moment, the Climate Change Commission focuses on emissions when reviewing New Zealand's methane reduction targets.
But the report said the focus should instead be on the warming impact of methane because temperature is what the Paris Agreement targets are based on.
Report co-author Myles Allen said taking an emission-focused approach is misleading if what hat people care about is temperature.
"Methane has a relatively short lifetime short on climate time scales around a decade and, as a result, if you stop putting methane into the atmosphere then concentrations of it in the atmosphere immediately start to fall which would draw temps down with them, so it has this leverage effect," Allen said.
Some climate scientists, including NIWA's Olaf Met, are treating the report's findings with caution.
"We are on course to significantly miss the targets. Faster action is needed, more action is needed so to give New Zealand farmers a pass in this situation is probably not quite right," Met said.
But farmers have said they want to be a part of the solution for the climate and the future of farming. New Zealand has targets to achieve net zero emissions of carbon dioxide and nitrous oxide by 2050 and to reduce methane emissions by 10 percent by 2030 and 24-47 percent by 2050.
"Farmers are quite happy to play their part in addressing climate change but it has to be based on science and that's what this report shows us," Acland said.
