Oxford professor Myles Allen has reiterated his call for methane accounting methods to be overhauled to recognise that methane is different to others greenhouse gases.
Speaking at the Environmental Protection Agency’s climate change conference, the Professor of Geosystems Science said it was worrying that the international standard (IPCC’s) accounting systems “pretend methane is equivalent to CO2, using something called the 100-year Global Warming Potential (GWP100).”
The professor warned that this GWP100 method understates the emissions reduction possible through decreases in methane.
Prof Allen explained that 1t of carbon dioxide (CO2) emitted to the atmosphere causes 0.45 trillionths of a degree (Celsius) increase in global temperature. He added that 1t of nitrous oxide has the same warming impact as 265t of carbon dioxide and that 1t/year of steady methane emissions has the same effect as 8t/year of steady carbon dioxide emissions.
However, he noted methane is different: “Any permanent decrease of methane emissions has the same warming impact as a one-off removal of 2,400t of CO2 or a decrease in methane emissions of 0.33%/year has the same impact as zero CO2 emissions.
“One of the most powerful levers you have is reducing methane emissions faster because of that enormous leverage effect of methane reduction. A 1t/year reduction in methane is worth a whole lot of avoided CO2.”
He called for farmers to be rewarded for reducing their impact on global temperature, pointing out that if a farmer moves to forestry they will be rewarded with payments, however a reduction in inputs or animal numbers does not result in any reward for the farmer.