The fast-fix for global warming that the UN climate summit can’t ignore

Despite rapid progress in clean energy and electric vehicles, the world is still warming faster than ever. The good news is that we already have powerful ways to reduce the warming rate – if governments look beyond carbon dioxide and focus on a broader set of pollutants.

We are writing this from the UN’s Cop30 climate summit in Belém, Brazil, where much of the attention is rightly on the carbon dioxide cuts that we need to avoid long-term warming. But we could make faster progress by also tackling a different set of pollutants that heat the planet intensely – but fade rapidly. Cutting emissions of these means cutting the warming quickly.

So-called “short-lived climate pollutants”, or SLCPs, are emitted in various ways and many of them have the same sources as CO2. The common ground is that they typically don’t stay in the atmosphere for very long – from a few days to a few decades, compared to centuries for carbon dioxide.

If carbon dioxide is the marathon runner of global warming, SLCPs are the sprinters, with a fast and powerful impact on global temperatures. Because cutting their emissions quickly reduces how much of them is in the atmosphere, they offer a real and rapid way to slow warming.

Methane, emitted from leaky gas pipes, belching cows, and rotting organic matter (think municipal solid waste) among other sources, is one of the most prevalent and powerful SLCPs. It only lasts in the atmosphere for about 12 years, but traps heat 80 times more effectively than carbon dioxide in that time. It’s easy to see how methane has accounted for around a third of global warming since the industrial revolution.

Atmospheric methane reached record levels last year, with an increase of over 3% since just 2019. Aggressive cuts could make a big contribution to slowing warming before mid-century – a timeline that really matters for the countries most affected by escalating climate change.

Other potentially game-changing SLCPs include tropospheric ozone, formed when sunlight reacts primarily with methane and nitrogen oxides. Ground level ozone is also a pollutant that damages human health as well as crops and ecosystems. Hydrofluorocarbons, or HFCs, used in air conditioning and refrigeration, are also incredibly powerful greenhouse gases.

Nitrogen oxides themselves, along with ammonia, volatile organic compounds and carbon monoxide, add to this mix, creating a cocktail of gases and other pollutants that aren’t carbon dioxide but are still able to change the climate. Cutting these pollutants helps human health, the climate and ecosystems.

But there is a flip side. One type of SLCPs (tiny airborne particles known as aerosols, emitted by burning fossil fuels and biomass among other sources) can temporarily cool the planet while they remain in the air. Whiter particles reflect sunlight back into space, while darker particles absorb it and warm the atmosphere. Aerosols also affect clouds, winds, and the strength of the monsoon.

This doesn’t mean we should delay reducing aerosols – keeping health-damaging pollutants in the air is hardly a climate strategy to be proud of – but it does mean that we need to accelerate action on other ways to stop the warming fast.

Fast moves

Many policies and technologies that target carbon dioxide can also reduce SLCPs. Shifting to renewable energy or electric vehicles also cuts methane, nitrogen oxides and aerosol emissions. Plans and policies focused on tackling short-lived pollutants, such as capturing methane emitted from landfill sites, disused coal mines, or stopping gas network leaks, also present quick and cost-effective wins.

Governments already know this. The Global Methane Pledge, launched at the Cop26 summit in Glasgow, highlights that cutting methane is our single most effective strategy for keeping 1.5°C within reach.

But a rapid acceleration is needed to meet its goal of reducing emissions by 30% by 2030, and at the moment too many countries, including key emitters who have signed the pledge (the EU and US) are not taking it seriously enough. Other major emitters like China and India haven’t signed up to the pledge, though backsliding from the west means that they have a chance to take the lead.

Other short-term pollutants may prove trickier. For example, HFCs are targeted by the 2016 Kigali amendment to the ozone layer-protecting Montreal Protocol.

This aims to phase them down by over 80% by 2050, but barriers to action include the costs of alternative technologies for developing countries and a black-market trade in HFCs. Global cooperation is needed to find solutions to these and other challenges.

What can Cop30 do?

SLCPs are clearly being discussed at Cop30, with influential non-state organisations like the Global Methane Hub, Clean Air Fund and Climate and Clean Air Coalition raising these issues. New initiatives like the Super Pollutant Country Action Accelerator, directly support developing countries in reducing methane and other non-carbon dioxide emissions.

But such ambitious action also needs to be taken at the highest level, by the governments negotiating the climate summit’s core outcomes, if we are to make use of this “emergency brake” on global warming.

The IPCC is set to publish a report on short-lived pollutants in 2027. This will not only raise the issue up the agenda but also provide governments with a sound basis on which to build policies and plans that tackle climate change and air pollution simultaneously.

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Piers Forster receives funding from UK and EU funding councils and he sits on the UK Climate Change Committee

Jessica Seddon is a co-chair of the Global Air Quality Forecasting and Information Services initiative of the WMO Global Atmosphere Watch. She is on the board of Radiant Earth and is a consultant/advisor to the Clean Air Fund.