Short lived climate pollutants
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Open Letter Calls for Greater Action to Cut Short-Lived Climate Pollutants, Including HFCs

The letter asks global leaders in government and business to prioritize SLCP mitigation in their climate action plans.

Nineteen environmental companies, universities and experts have signed an open letter on the importance of short-lived climate pollutants (SLCPs) in national and corporate climate action plans, urging “broad and swift action to abate their emissions.”

SLCPs include HFCs, methane, soot (black carbon), carbon monoxide and aviation contrails, which together account for nearly half of industrial-era global heating.

Unlike CO2, the primary greenhouse gas, which is produced by fossil fuel combustion and remains in the atmosphere for hundreds to thousands of years, SLCPs have much shorter atmospheric lifetimes on the scale of years to days. Feasible SLCP cuts from existing technologies today can avoid up to 0.6°C (1.1°F) by 2050, which is four times more in that time period than CO2 cuts alone, the letter said.

“One of the fastest, most efficient solutions to prevent us from reaching dangerous levels of warming is to look beyond only carbon dioxide (CO2) and rapidly reduce short-lived climate pollutants,” the letter said. In regard to HFCs, the letter pointed to improved refrigerant management and deployment of low-GWP refrigerants.

The signatories to the letter include RecoolitProject DrawdownTerrasetCarbon Containment LabInternational Fugitive Emissions Abatement AssociationCNaughtEffecterraRefrigerant Emissions Elimination ForumLIFT EconomyFrost Methaneclimate-iVeridienThe Sky FoundationKristen TaddonioProf. Gus J.M. Velders of Utrecht UniversityDr. Tom Hooper of University College Dublin and Dr. Pallav Purohit of the International Institute for Applied Systems Analysis.

The signatories to this letter take a wide variety of perspectives on the most promising pathways and approaches to SLCP mitigation,” the letter said. “However, all signatories agree that SLCP emissions are a neglected and critical area to invest in over the next five years to prevent the worst impacts of climate change.”

The letter continued, “We call on global leaders in government and business to prioritize SLCP mitigation in their climate action plans, and for entities such as standards bodies and think tanks to support these efforts.”

The letter invited other organizations to sign the letter or send inquiries by emailing

Better corporate standards

Corporations need better standards to guide accounting for and mitigating their SLCP emissions, as well as incorporating SLCPs into their Beyond Value Chain Mitigation (BVCM) efforts, the letter said. (BVCM is defined in the SBTi [Science-Based Targets Initiative] Corporate Net-Zero Standard as “mitigation action or investments that fall outside a company’s value chain, including activities that avoid or reduce GHG emissions, or remove and store GHGs from the atmosphere.”)

The letter suggests three steps corporations can take:

  • Report separate emissions for each climate pollutant, as recommended by leading climate scientists. Then set separate reduction targets for each pollutant.
  • When a unified metric is required, report multiple metrics. At the very least, GWP-20, basing GWP on 20 years, should always accompany GWP-100, based on 100 years. Side-by-side reporting could allow corporations and watchdog organizations to explicitly assess and prioritize progress across both short-term and long-term mitigation opportunities. “It is clear that GWP-100 by itself is inadequate for meeting our near-term climate goals,” the letter said.
  • Pursue an SLCP-informed approach to climate action, both inside an emissions boundary and outside it. Choose to set Scope 1, 2 and 3 reduction targets separately for different pollutants over time.

On the national level, the Climate and Clean Air Coalition (CCAC), has supported efforts such as the development of National SLCP Plans, the letter noted. However, it added, fewer than 20 countries have endorsed national SLCP plans, and only 54% of countries’ Nationally Determined Contributions (NDCs) included HFC reduction according to the latest UNFCCC synthesis report.

The letter called for standards bodies to develop new corporate standards (or amend existing ones, as appropriate) to incorporate urgency on SLCPs across reporting, mitigation efforts, and BVCM. In addition, corporations could “experiment and try their own SLCP-informed approaches while such standards are being developed or amended.”

The letter referred to existing initiatives on SLCPs, including: the Global Methane Pledge, the new Global Cooling Pledge from COP28, the Madrid Call on Fast Action on Super Pollutantsthe Astra ProjectClimate and Ozone Protection Alliance (COPA) and others. “However,” it added, “more needs to be done. We call for an increase in resources and support to existing projects, the development of new efforts focused on these strategies, and increased prioritization of these issues by countries and corporations alike.”

In 2022, researchers at the Institute for Governance and Sustainable Development (IGSD) in Washington, D.C., concluded that inaction on short-lived climate pollutants like HFCs risk undermining the efforts to limit global warming.

“One of the fastest, most efficient solutions to prevent us from reaching dangerous levels of warming is to look beyond only carbon dioxide (CO2) and rapidly reduce short-lived climate pollutants.”

Open letter on SLCPs

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