Carbon removal projects could prove vital in offsetting methane emissions – the second largest contributor to global warming.

Nature-based schemes that aim to remove CO2 through methods such as afforestation and reforestation are criticised for being temporary – the carbon removed is often re-released once projects end – as well as fraught with risk. 

But climate change researchers have shown they can play an important role in neutralising the environmental impact of methane.

Methane and carbon dioxide behave differently over time: methane warms the planet much more rapidly than carbon dioxide, causing more damage in the short to medium term, but methane has little long-term impact on global temperatures as it dissipates over time. 

A ton of carbon dioxide emitted has a smaller temperature effect than a ton of methane, but one that is effectively permanent. For policymakers the value of a temporary carbon removal could depend on how we value different generations – present vs future – with different time priorities leading to different decisions.

Using temporary removals to tackle CO2 emissions could also mean present generations forcing far-future ones to foot the bill for permanent storage commitments when those removals, the researchers say.

Their solution is to use temporary CO2 removals to counteract the short-term impact of methane. 

They calculate that a well-designed temporary removal lasting around 30 years can closely match methane’s short-term warming while being relatively low-cost and requires relatively easy-to-monitor contracts.

Permanent removals are more expensive, depend on uncertain economic assumptions and require a perpetual commitment to storage, which is difficult to monitor. 

The researchers estimate that 87 temporary, 30-year removals of 1 tonne of CO₂ are equivalent to 1 tonne of methane emitted, giving policymakers a concrete formula for deciding whether to cut methane emissions directly or offset it with temporary CO₂ removals.

“Meeting the goals of the Paris Agreement requires reducing temperatures in both the short and long term,” said Professor Ben Groom, Dragon Capital Chair in Biodiversity Economics at the University of Exeter Business School and a co-author of the study alongside the economists Professor Dr Wilfried Rickels from the Kiel Institute of for the World Economy and Professor Frank Venmans from LSE. 

“Rather than seeing the temporary nature of land-based carbon removals as a weakness, we show that it can be an advantage when used to counter methane’s short-lived warming. This approach could unlock new climate finance for nature-based solutions and deliver immediate relief from temperature stress.”

Reducing the large short-lived impact of methane emissions with temporary carbon removals is published in Nature Climate Change.

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