Targeting methane

Carbon dioxide may be climate enemy number one, but we also have to deal with the rest of the greenhouse gang – especially methane. Fossil fuel extraction, livestock farming, and waste processing have tripled the atmospheric concentration of methane since pre-industrial times, and it now accounts for almost a third of human-made global warming.

The good news is that cutting methane is one of the most cost-effective ways to rein in climate change over the next few decades. This is the conclusion of two UN reports published in 2021, both informed by recent IIASA research. These reports supported the new Global Methane Pledge, in which countries promise to cut their collective methane emissions.

A critical question is how ambitious those cuts should be. Aim too high, and they might not be feasible; aim too low, and the climate suffers. Finding the answer is not simple, because methane is a slippery customer. It is difficult even to calculate how much is being emitted today.

“If you know how much carbon is in a fuel, then you know how much CO₂ comes out when you burn it, but for methane there is no such easy relationship,” says Lena Höglund Isaksson, a senior research scholar in the Energy, Climate, and Environment Program at IIASA. “It depends very much on the technology, and other parameters like climatic conditions and operational practices.” 

Höglund Isaksson and her team try to account for these factors using the Greenhouse Gas and Air Pollution Interactions and Synergies (GAINS) model developed at IIASA. GAINS combines reported activity levels in different industries with information about emissions from specific technologies, including country- and sector-specific details such as the age and status of gas pipelines. This enables researchers to assess current emissions, and project the cost and effectiveness of measures to curb them. Some of the most effective measures are stopping methane from escaping during fossil fuel extraction and transport, reducing the organic waste going to landfill, and breeding livestock to improve animal health and productivity.

In a 2020 paper, the team used GAINS to project future emissions pathways. This was one of the main inputs to the UN’s 2021 Global Methane Assessment, as well as a chapter on methane in the 2021 Emissions Gap Report, which both concluded that a cut of around 30% should be feasible by 2030 (using affordable technologies focused on methane, and not including broader measures such as reducing fossil field use and changing diets). That would cut about 0.2°C off global warming in 2040, reducing the risk of irreversible changes to climate and ecosystems.

This figure was adopted by the signatories to the Global Methane Pledge, launched in November 2021 at COP26. They commit to cutting their collective methane emissions by 30% in 2030, relative to 2020 levels. More than 100 countries have signed up so far, accounting for about half of global methane emissions.

It is hard to see how this could have happened without scientific guidance.

“We are producing a kind of map, which policymakers need to navigate with,” says Höglund Isaksson. “It has to be a credible map that everyone can agree on, based on consistent global modeling rather than separate national projections. IIASA is a good place to do that because we are neutral and international.”

References

Höglund-Isaksson, L., Gomez-Sanabria, A., Klimont, Z., Rafaj, P., & Schöpp, W. (2020). Technical potentials and costs for reducing global anthropogenic methane emissions in the 2050 timeframe –results from the GAINS model. Environmental Research Communications 2 (2) e025004. DOI: 10.1088/2515-7620/ab7457. [pure.iiasa.ac.at/16324]