Reducing Short-Lived Climate Pollutants is the Last, Best Hope At Stemming Loss and Damage

Parties reached a breakthrough agreement on the last day of COP27 to provide “loss and damage” funds to the countries that will experience the worst effects of climate change — countries that in most cases have also contributed little to the emissions causing it.

Loss and damage includes the impacts of climate change that are unlikely to be reversed — including sea level rise, melting glaciers, desertification, and reduced biodiversity — which will have a devastating impact on the world’s poorest populations. This decision highlights this decade’s imperative to avoid as much loss and damage as possible, while helping vulnerable populations adapt to the climate change impacts that are now unavoidable. 

Reducing short-lived climate pollutants (in tandem with carbon reduction) is the only strategy we have to prevent some of these losses in the short term.

“SLCPs are the only way to turn down the heat in the next couple of decades. When it comes to the parts of loss and damage that are related to these long-term cumulative effects, like sea level rise, the only way to reduce them in the short term is by quickly addressing short-lived climate pollutants,” said Nathan Borgford-Parnell, Science Affairs Officer at the Climate and Clean Air Coalition (CCAC). “While reducing carbon dioxide is really critical, its long lifetime means you’re not going to enjoy the benefits of mitigation for a number of decades, so you really have to do both immediately — CO2 because of the long term and SLCPs because of the near-term.”

Much of the work to avoid loss and damage centers around sea level rise, which has increased more since mid-century than the mean rate during the last two millennia. Research by C40 finds that by 2050, 800 million people will live in cities where sea levels could rise by more than half a meter — and many of these will be major global cities like Tokyo, Miami, and Dhaka. In regions like the Indian and Western Pacific Oceans, sea level rise is expected to be 10 to 20 percent higher than the global average. Without dramatic action, entire island nations could be swallowed by the sea.

Cutting SLCPs could reduce the rate of sea level rise by 20 percent in the first half of the century and 30 percent by the end of the century, when combined with CO2 mitigation, according to the CCAC’s Time to Act to Reduce Short-Lived Climate Pollutants report. And while many of the impacts of climate change are already baked in, slowing the rate at which these changes occur could give coastal communities and developing island states a small but vital window of time to adapt.

The earth’s cryosphere — including Antarctica, the Arctic, and the world’s glaciers — is also being impacted by climate change, impacts that will only intensify without action. A report by the International Centre for Integrated Mountain Development (ICIMOD) found that even if global warming is kept under 1.5 degrees, the Himalayas and the Hindu Kush range in Afghanistan would experience 2.1 degrees warming, resulting in one-third of the glaciers melting. If current emissions aren’t stemmed, the region could warm five degrees and lose two-thirds of its glaciers by the end of the century. Reducing short-lived climate pollutants could slow the melting of some glaciers.

“The severe impacts that we’re experiencing today are already due to climate change and this means that we need to slow warming today because the severity of those impacts is only going to increase with every fraction of a degree of warming,” said CCAC Scientific Advisory Panel Member Dr. Gabrielle Dreyfus, Chief Scientist, Institute for Governance and Sustainable Development at a presentation at COP27. “When you cut these short-lived climate pollutants in the near term you actually get four times more of the avoided warming by 2050 than CO2 alone — again, this is not an either/or, this is a both/and solution because you’ve got to keep 1.5 alive so we can do the marathon to decarbonize,” said Dreyfus. “If we start cutting methane today we can start to see the impacts within this decade.”

Reducing short-lived climate pollutants could also support a healthier, more resilient population, better equipped to contend with a world impacted by climate change.

Reducing methane by 45 percent — a possibility this decade — wouldn’t just avoid nearly 0.3°C of global warming by 2045 and keep the Paris Agreement within reach, but it would also prevent 260,000 premature deaths and 775,000 asthma-related hospital visits. Methane also plays a sizable role in reducing crop yields, which means that those reductions could also avert 25 million tonnes of crop losses every year. Given that climate change is projected to have a negative impact on the world’s food production, averting such losses could be huge when it comes to adapting to a warmer planet.

“When it comes to resiliency, when it comes to avoiding loss and damage, we really need to pull these fast levers in terms of short-lived climate pollutants to reduce the rate of change now — to avoid tipping points, to avoid significant sea level rise — but also to improve the resiliency of our populations. One of the ways to do that is by reducing SLCPs, which in turn will reduce the burden of disease and morbidity, and will actually increase the resiliency of populations to these impacts,” said Nathan Borgford-Parnell. “It’s a one-two punch — you’re avoiding future losses, but you’re also simultaneously strengthening the human population and the ecosystem by reducing the amount of air pollution they’re exposed to on a daily basis.”