We need to think about more than just CO2

What’s happening? Making sharp reductions in all greenhouse gases immediately is essential if the world is to effectively tackle global warming, according to a study by US scientists. The researchers argued that cutting methane and other “short-lived climate pollutants” (SLCPs) including soot would decrease near-term warming and give the planet “a fighting chance” of avoiding climate catastrophe. (The Guardian, PNAS)

Why does this matter? When thinking about climate change, it’s easy to get stuck in the CO2 lens. And for good reason – it’s responsible for around two-thirds of human-caused warming over long timescales. Its concentration in the atmosphere is also way above where it has ever been, as far back as we can record it.

However, CO2 isn’t the whole picture, and to successfully mitigate climate change means thinking about other pollutants. We can’t keep temperature rises to 1.5C – the Paris Agreement’s preferred goal – by just considering CO2 alone. SLCPs like nitrous oxide, hydroflurocarbons, ground-level ozone and soot will also need to be addressed.

The latter is particularly important, as it has pronounced effects in the Arctic where it can settle on ice and snow and increase rates of melting. This can then have knock-on effects for the rest of the climate system.

A methane mystery – There’s another carbon-related molecule the US study is quite clear about the importance of tackling – methane. This extremely potent greenhouse gas stays in the atmosphere for a shorter amount of time than CO2 but causes 80 times more warming over a 20-year period. The latest Intergovernmental Panel on Climate Change report says methane emissions need to decline 34% by 2030 if we are to limit warming to 1.5C.

There’s a problem though – methane emissions are currently rising by record levels. Even more worryingly, no-one quite knows exactly where they are coming from.

One thing is certain: leaks from oil and gas infrastructure are definitely underestimated, as a number of studies clearly highlight. Some facilities have been leaking significant amounts into the atmosphere for decades. The gas could even be escaping into the atmosphere from your unlit stove.

Cost-effective action – Thankfully, the International Energy Agency, which says methane emissions from the energy sector are at least 70% above official reports, says there’s no reason not to address the problem as it can be tackled at no net cost. If leaks are identified and fixed, which is increasingly viable thanks to satellite-based detection technology, this means more efficient operations and more gas to sell – which could even result in a net profit with gas prices at today’s levels.

A further thought – The energy sector is a significant methane source, responsible for around 40% of human-caused methane emissions, but agriculture is also a significant methane emitter. Now, similar to oil and gas facilities, emission fingerprints from specific agricultural locations can be detected remotely.

GHGSat has recently detected cattle emissions from space for the first time. This opens up the possibility of farmers’ pledges to reduce methane emissions being remotely audited, and the efficacy of changing ruminant diets – for example by feeding them seaweed – effectively monitored.

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