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.
Why SLCPs?
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?
Waste is another good example. You can tap the gas from a landfill, but the better plan would be not to send organic matter to landfill in the first place, which requires a more fundamental rethink of waste management systems. This is technically feasible – WSP’s waste management teams have delivered many such projects around the world – but it does involve multiple layers of government, changes in household behaviour, and much more besides.
There are also critical supply-side factors: there is not enough dedicated funding for methane reductions or sectors such as waste or agriculture. This is particularly true of the finance available to developing countries. Instead, these initiatives tend to fall under broader programmes that channel the still-too-scarce funding from developed countries to help developing countries implement the Paris Agreement. They are often competing with projects that are more easily scoped and presented to funders, so they lose out.
These are not expensive projects – but that can work against them too. The marginal costs can be low or even net-positive, which creates the perception that developing countries should be able to implement them using their own resources.
Here, the push and pull of international climate politics needs to take a back seat and let science be the driver: funding for greenhouse gas mitigation should be increased and it should flow where it can make a difference in avoiding catastrophic tipping points.
Benefits beyond climate
To spur action on SLCPs, we could point to the significant additional benefits that would result, beyond rapidly slowing the pace of climate change. Methane is a resource and it has an economic value that should not be wasted. By improving the efficiency of our existing natural gas production, processing and transmission systems, even as the economy shifts to zero-emissions sources, countries can improve their energy security. This would also bring a financial benefit for a sector that has a major transition challenge ahead. Converting multiple streams of organic waste – from consumers, from agriculture, from fisheries – into energy or fertilizer via biodigestion transforms them into a valuable, low carbon resource.
As well as unlocking hidden value, addressing pollution benefits communities and has far-reaching impacts on human health. According to the Global Methane Assessment by UNEP/CCAC, cutting methane emissions by 45% would not only be the most cost-effective way to avoid critical tipping points but also prevent 260,000 premature deaths, 775,000 asthma-related hospital visits, 73 billion hours of lost labour from extreme heat and 25 million tonnes of annual crop losses.
For governments and corporations looking to make immediate emissions reductions, these pollutants are the low hanging fruit. We understand the systems, we know what to do, we have the technology to do it, and it makes economic and financial sense. Let’s not wait any longer to step up our action and funding to make a real difference, fast.
