“Methane and the Paris Agreement temperature goals” has been published in a Royal Society journal and authored by internationally respected scientists and policy experts including New Zealanders Professor Dave Frame and Dr Adrian Macey.
The report sets out how reducing methane emissions starts to reverse methane-induced warming within a few decades, unlike carbon dioxide which continues increasing global mean temperature until net-zero emissions are reached. It says these differences are hidden when framing climate mitigation using annual ‘CO2-equivalent’ emissions, and that a better approach is to use ‘warming-equivalent emissions’ through GWP*.
The report recommends governments measure and report on the annual warming impact of short-lived and long-lived gases in addition to annual emissions, including in their NDCs (nationally determined contributions) to address climate change.
B+LNZ chief executive Sam McIvor says the report is part of an increasing body of scientific evidence about appropriate metrics.
“It builds on the recent IPCC report that clearly set out how methane’s warming contribution is overstated when emissions are not increasing – as has been the case in New Zealand.
“We’ve repeatedly called on the Government to report on annual emissions and warming, and said the Climate Change Commission budgets should be based on warming rather than emissions.
“The Paris Agreement aims to keep the average temperature increase to within 1.5 degrees Celsius, and this is reflected in the targets set under the Climate Change Response Act. Given goals are about warming the conversation about targets needs to be framed in terms of warming impacts.
“It’s vital we use the right metrics, so that we fully understand the relative impact each sector is having on the climate and warming, and therefore what actions each sector needs to take.
“Because we’re using the wrong metrics – that is, GWP100 – there are two major misconceptions about New Zealand. First, that agriculture is contributing 48 percent of emissions and therefore by implication 48 percent of warming that year. Second, that agriculture was let off the hook by the 24 to 47 percent methane reduction targets in the Zero Carbon Act.
“There’s a fundamental difference between short-lived and long-lived gases, and as a result between emissions reduction targets and warming reduction targets. That’s why we have a split gas approach in the Climate Change Response Act. The Government was right to use this approach. However, they haven’t properly explained the science to the public or followed up with parallel reporting and appropriate targets.
“Let’s be clear our sector is committed to our climate change responsibilities. We do need to take action on methane. Given methane’s short-lived but potent impact it’s important that we aim to prevent any further warming.
“We’re committed to the He Waka Eke Noa primary sector climate action partnership but in parallel we’re working hard to ensure that what we are asked to do in future is fair and equitable.”
For more information, please contact B+LNZ’s Katie Jans on email@example.com or 027 838 6353
Cain Michelle, Jenkins Stuart, Allen Myles R., Lynch John, Frame David J., Macey Adrian H. and Peters Glen P. 2022 Methane and the Paris Agreement temperature goals. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 380: 20200456. https://doi.org/10.1098/rsta.2020.0456