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Researchers propose new methane emissions metric for climate policy

In a new paper, a group of researchers have outlined a better way to think about how methane and other gases contribute to greenhouse gas (GHG) emissions budgets.
"There are two distinct types of emissions, and to properly address climate change and create fair and accurate climate change policy we must treat these two groups differently," says Professor Dave Frame, Head of the Climate Change Research Institute at Victoria University of Wellington, New Zealand.

Cow 5469 peers out of her shed at Wapnö dairy farm in Sweden, probably wondering what the fuss is about. The manure based biogas energy system together with an innovative heat-driven absorption refrigeration process supplies the heat, power and cooling needs for Wapnö.

Cow 5469 peers out of her shed at Wapnö dairy farm in Sweden, probably wondering what the fuss is about. The manure based biogas energy system together with an innovative heat-driven absorption refrigeration process supplies the heat, power and cooling needs for Wapnö.

The paper “A solution to the misrepresentations of CO2-equivalent emissions of short-lived climate pollutants under ambitious mitigationpublished June 4 in the journal Nature Climate and Atmospheric Science has outlined a better way to think about how methane and other gases contribute to greenhouse gas (GHG) emissions budgets.

Current climate change policy suggests a ‘one size fits all’ approach to dealing with emissions. But there are two distinct types of emissions, and to properly address climate change and create fair and accurate climate change policy we must treat these two groups differently, said Professor Dave Frame, Head of the Climate Change Research Institute at Victoria University of Wellington, New Zealand and one of the co-authors of the paper.

This is an important step towards evaluating the warming from methane emissions when developing strategies to achieve the goals of the Paris Agreement.

Long-lived pollutants, like carbon dioxide (CO2), persist in the atmosphere, building up over centuries. The CO2 created by burning coal in the 18th century is still affecting the climate today. Short-lived pollutants, like methane (CH4), disappear within a few years. Their effect on the climate is important but very different from that of CO2: yet current policies treat them all as ‘equivalent‘, said Dr Michelle Cain from the Oxford Martin Programme on Climate Pollutants.

The research demonstrates a method of defining equivalence between the different emissions, which takes into account the lifetime effects. This would be particularly relevant to industries like agriculture, which contribute a large proportion of GHG emissions using traditional methods in some countries, for example, New Zealand.

We don’t actually need to give up eating meat to stabilise global temperatures. We just need to stop increasing our collective meat consumption. But we do need to give up dumping CO2 into the atmosphere. Every tonne of CO2 emitted is equivalent to a permanent increase in the methane emission rate. Climate policies could be designed to reflect this, said Professor Myles Allen who led the study.

Meat production is a major source of methane within agriculture.

Under current policies, industries that produce methane are managed as though that methane has a permanently worsening effect on the climate. But this is not the case. Implementing a policy that better reflects the actual impact of different pollutants on global temperatures would give agriculture a fair and reasonable way to manage their emissions and reduce their impact on the environment, said Professor Frame.

The work, which is a collaboration between researchers at Victoria University of Wellington, New Zealand, the Universities of Oxford and Reading in the UK, and the Centre for International Climate Research in Norway (CICERO), shows a better way to think about how methane might fit into carbon budgets.

Implementing a policy like this would show New Zealand to be leaders and innovators in climate change policy. Implemented successfully, it could also completely stop New Zealand’s contribution to global warming, said Professor Allen.

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