Eliminating HFCs faster will cut climate harm

Eliminating chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) from our refrigerators and air-conditioning units, thereby helping the ozone hole to heal, has been a global success story. But the hydrofluorocarbons (HFCs) used to replace CFCs and HCFCs are potent greenhouse gases. Now a study shows that early action to reduce HFCs could bring huge benefits, with more than 90% of the atmospheric impacts of HFCs avoided if they are phased out by 2030.

Although HFCs don’t hang around in the atmosphere for as long as carbon dioxide, some can cause thousands of times more warming per kilogramme over the course of a few decades. Atmospheric emissions of HFCs are increasing rapidly, in response to rising global demand for technologies such as air conditioning and refrigeration.

However, the potential global warming hazard from HFC emissions has been recognised. Last October, at the 28th Meeting of the Parties to the Montreal Protocol, the Kigali Amendment to phase down HFCs was adopted by 197 countries. Under the amendment, countries committed to cut the production and consumption of HFCs by more than 80% over the next 30 years.

How much difference to climate will fast action to phase out HFCs make? To answer this question, Margaret Hurwitz from the NASA Goddard Space Flight Center, US, and her colleagues used coupled chemistry-climate models to quantify the relative contribution of HFCs to future atmospheric change, and the effects of different HFC mitigation scenarios.

The researchers looked at four hypothetical scenarios: one with business-as-usual emissions of all greenhouse gases, and three others where HFCs were phased out by 2020, 2030 and 2040 respectively, while all other greenhouse gases continued with business-as-usual emissions. In all cases, the team examined the change in surface radiative forcing and the temperature response in the upper troposphere and stratosphere between now and 2050.

The results clearly show that early action on HFCs could have a significant impact on global warming in the near-term, with more than 90% of the climate impacts of HFCs avoided if they are phased out by 2030.

“The climate impacts of increasing carbon dioxide are expected to be larger than those of the HFCs, but we show that reducing HFCs could make a substantive contribution to future atmospheric change,” said Hurwitz, whose findings are published in Environmental Research Letters (ERL).

Phasing out HFC emissions as fast as possible can only be beneficial, but it won’t necessarily be easy. It is possible to replace HFCs with compounds that have lesser climate impacts, or to adopt technologies such as water-cooling systems that don’t rely on HFCs, but it may take some time to find solutions that can be implemented globally across a broad range of applications.