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Hydrofluorocarbon emissions have increased rapidly and are managed by the Kigali Amendment to the Montreal Protocol. Yet the current ambition is not consistent with the 1.5 °C Paris Agreement goal. Here, we draw on the Montreal Protocol start-and-strengthen approach to show that accelerated phase-down under the Kigali Amendment could result in additional reductions of 72% in 2050, increasing chances of staying below 1.5 °C throughout this century.

Split air conditioners (ACs) are the most used appliance for space cooling worldwide. The phase-down of refrigerants with high global warming potential (GWP) prescribed by the Kigali Amendment to the Montreal Protocol has triggered a major effort to find less harmful alternative refrigerants. HFC-32 is currently the most common refrigerant to replace HFC-410A in split ACs. The GWP of HFC-32 is about one-third that of HFC-410A but still considerably higher than that of a growing number of nonfluorinated alternatives like propane with a GWP of <1, which have recently become commercially available for split ACs. Here, we show that a switch to propane as an energy-efficient and commercially available low-GWP alternative in split ACs could avoid 0.09 (0.06 to 0.12) °C increase in global temperature by the end of the century. This is significantly more than the 0.03 (0.02 to 0.05) °C avoided warming from a complete switch to HFC-32 in split ACs.

We assess that full global compliance with the Kigali Amendment to the Montreal Protocol will not provide emission reductions consistent with the 1.5oC target of the Paris Agreement. Following the Montreal Protocol’s start-and-strengthen approach to refrigerant management, fast-tracking hydrofluorocarbon phase-down under the Kigali Amendment would result in additional reductions vital for achieving the Paris climate goals. This would also increase chances of staying below 1.5oC additional warming throughout this century.

Cooling is needed to protect vulnerable populations from heatwaves, keep vaccines viable and food fresh, and workforces productive. It is essential for equity and development, especially as climate change raises global temperatures. There are an estimated 3.6 billion cooling appliances in use globally today, and that number is growing by up to 10 devices every second. This growth is set to increase the sector’s greenhouse gas emissions dramatically. Air conditioners are a double burden. In most cases, they use hydrofluorocarbons (HFCs), extremely potent greenhouse gases, and require significant energy to run. Without policy intervention, direct and indirect emissions from air conditioning and refrigeration are projected to rise 90 per cent above 2017 levels by the year 2050. This report lays out ways to resolve this dilemma by delivering efficient and climate friendly cooling for all – in particular by rapidly phasing down hydrofluorocarbons in the cooling sector and delivering cooling more efficiently through more efficient equipment and more efficient buildings.

The post-2015 development agenda is dominated by a set of Sustainable Development Goals (SDGs) that arose from the 2012 Rio+20 United Nations Conference on Sustainable Development. The 17 goals and 169 targets address diverse and intersecting aspects of human and environmental needs and challenges. Achieving the SDGs by 2030 requires implementing coordinated and concerted strategies and actions that minimize potential trade-offs and conflicts and maximize synergies to contribute to multiple SDGs. Measures to mitigate emissions of short-lived climate pollutants are an example of actions that contribute to multiple outcomes relevant to development. This Perspective highlights the interlinkages between these pollutants and the SDGs, and shows that implementing emissions reduction measures can contribute to achieving many of the SDGs.

The Paris Climate Agreement under the United Nations Framework Convention on Climate Change (UNFCCC) explicitly links the world's long-term climate and near-term sustainable development and poverty eradication agendas. Urgent action is needed, but there are many paths toward the agreement's long-term, end-of-century, 1.5° to 2°C climate target. We propose that reducing short-lived climate pollutants (SLCPs) enough to slow projected global warming by 0.5°C over the next 25 years be adopted as a near-term goal, with many potential benefits toward achieving Sustainable Development Goals (SDGs). As countries' climate commitments are formally adopted under the agreement and they prepare for its 2018 stocktaking, there is a need for them to pledge and report progress toward reductions not just in CO2 but in the full range of greenhouse gases (GHGs) and black carbon (BC) (plus co-emissions) in order to track progress toward long-term goals.