Carbon dioxide may be the biggest greenhouse gas by volume, but it’s not the only one that we urgently need to curb. Pollutants such as methane and hydrofluorocarbons (HFCs) account for a much smaller proportion of emissions, and have a shorter lifespan in the atmosphere – but they are far more potent and act much more quickly.
Known as “short-lived climate pollutants” (SLCPs), these chemicals are responsible for up to 45% of current global warming, with methane alone responsible for around 30%. Tackling SLCPs is no substitute for the major industrial transformation that will be necessary to reach net-zero, limit climate change to well below 2°C and keep the planet liveable. But it does offer our best chance for rapid, near-term mitigation – and of avoiding the tipping points beyond which scientists believe the impacts will become irreversible and self-reinforcing.
The CO2 we emit today will remain in the atmosphere for centuries. In contrast, methane has a lifetime of about 12 years – but a global warming potential (GWP) that is more than 80 times greater, measured over a 20-year period. HFCs break down after about 15 years, but before they do, their GWP can be thousands of times higher.
Because they are short-lived, reducing emissions of these pollutants could lower their concentration in the atmosphere relatively quickly, and act to slow or even reverse their strong climate-forcing effect.
They also present a clearer target: cutting atmospheric CO2 levels will take long-term action on many fronts, but the majority of SLCPs are produced by a few key sources. Methane is generated by the breakdown of organic matter in landfill, by agriculture – particularly rice farming and cattle – and it leaks from natural gas systems. Hydrofluorocarbons are man-made chemicals used for applications such as air-conditioning, refrigeration, solvents and aerosols.
We have the technical fixes too: they are well understood, ready to implement and come with a whole host of economic, social and environmental co-benefits. Half of the measures to cut methane emissions would more than pay for themselves, for example.
There are, however, some key barriers to progress, many of which are financial. Understanding these is key to overcoming them, and to slowing the pace of climate change in the near-term.
Overcoming Financial Barriers
WSP has been working with the Clean Air Task Force, one of the world’s leading environmental advisory organizations, to find out why existing solutions for reducing methane emissions have not been implemented more widely.
First, there are demand-side factors: the complexity and distributed nature of waste and agricultural systems and their governance make it hard to scope and structure a bankable project that will lead to meaningful results. Take farming: how do you engage rice farmers or cattle producers in communities around the world to change their practices, for a wider environmental purpose that they may not see as relevant to their short-term subsistence or production needs?