CSIRO data used to prove HFC-23 greenhouse gas on the rise

January 29th, 2020

An apartment block building with air conditioners appearing on many windows

In a recent Nature Communications paper, CSIRO’s atmospheric observations were used to help prove that HFC-23 emissions have increased and in 2018 were higher than at any point in history. Image credit: Flickr/zeevveez (CC BY 2.0)

CSIRO has contributed to an international study on rising levels of hydroflourocarbon-23 (HFC-23), a greenhouse gas that is 12,400 times more potent than carbon dioxide in the atmosphere.

HFC-23 is an unwanted by-product of chlorodifluoromethane (HCFC-22) production; HCFC-22 is used largely in air conditioning equipment. Because of its role in ozone layer depletion, HCFC-22 was phased out in the late 1990s.

Under the Montreal Protocol and its Clean Development Mechanism, HCFC-22 production processes were modified such that HFC-23 emissions should have dropped by nearly 90% between 2014 and 2017 if voluntarily adopted by developing countries. However, atmospheric observations, which included CSIRO’s Cape Grim air archive and Antarctic firn air data showed that HFC-23 emissions have instead increased, and reached a peak level in 2018.

CSIRO atmospheric researcher Paul Fraser, who has conducted research on CFCs for over 40 years, said that the research paper was a global study with implications for developing countries such as India and China, whose phase-out programs for HCFCs, as allowed under the Protocol, trailed 10-15 years behind developed countries including Australia.

“Air conditioning and refrigeration systems have relatively long shelf lives of approximately 10 years,” said Paul.

“Transitioning to less polluting technologies remains a challenge for citizens in developing countries,  both in implementing national programs to reduce greenhouse gas emissions, and producing and adopting improved technologies.”

“The good news is that we expect a positive response from developing countries and HFC-23 levels to stop growing in the atmosphere in the next decade.”

The findings, which were led by the University of Bristol, were published in Nature Communications last week.

Further information


Stanley, K.M., Say, D., Mühle, J. et al. Increase in global emissions of HFC-23 despite near-total expected reductions. Nat Commun 11, 397 (2020). https://doi.org/10.1038/s41467-019-13899-4