We need to focus on methane emissions not just CO2 to save the planet

When it comes to greenhouse gases, carbon dioxide tends to make the headlines, but countries need to focus on other gases such as methane, a new study has shown.

A new Duke University study compares two approaches to climate change — one cutting just CO2 emissions and another cutting a broad range of greenhouse gases.

The study found that if reductions of methane and other overlooked gases were cut as well as CO2, the rate of global warming could be halved by 2050.

Co-author Drew Shindell, Nicholas distinguished professor of Earth Science at Duke University, said: "Decarbonisation is crucial to meeting our long-term climate goals, but it's not enough.

"To slow warming in the near-term and reduce suffering from the ever-increasing heatwaves, droughts, super storms and fires, we need to also reduce short-lived climate pollutants this decade."

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The new research shows that focusing our efforts almost exclusively on cutting carbon dioxide emissions, as most governments currently do, can no longer prevent global temperatures from rising above pre-industrial levels by 1.5ºC.

Shindell said: "Our analysis shows that climate pollutants such as methane, nitrous oxide, black carbon soot, low-level ozone and hydrofluorocarbons contribute almost as much to global warming as longer-lived CO2.

"Since most of them last only a short time in the atmosphere, cutting them will slow warming faster than any other mitigation strategy."

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It would also help us avoid a short-term warming "backlash" that the Intergovernmental Panel on Climate Change (IPCC) has warned could occur by cutting fossil fuel emissions alone.

Recent IPCC reports have projected that decarbonising the energy system and shifting to clean energy in isolation could perversely cause temperatures to rise for a while because, in addition to CO2, fossil fuel emissions contain sulphate aerosols, which act to cool the climate for a very short time - from days to weeks — before they dissipate.

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The new study accounts for this effect and concludes that focusing exclusively on reducing fossil fuel emissions could result in "weak, near-term warming".

This could potentially cause temperatures to exceed the 1.5°C level by 2035 and the 2°C threshold by 2050.

In contrast, reducing both CO2 and other climate pollutants simultaneously would significantly improve our chance of remaining below the 1.5ºC mark.

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