Tracking and tackling unreported CFC emissions

Research Highlights

• Pinpointed unreported emissions from northeastern China that were a major breach of the Montreal Protocol. 
• Influenced swift enforcement actions by Chinese authorities, including shutting down illegal production facilities. 
• Helped reduce emissions equivalent to cutting all annual CO₂ emissions from a city the size of London.

The challenge of unreported emissions 

In 2016, scientists noticed an unexpected and persistent rise in atmospheric concentrations of CFC-11, an ozone-depleting substance (ODS) that has been banned globally since 2010 under the UN’s Montreal Protocol.  

Data revealed emissions increases of 11,000 to 17,000 tonnes annually during 2014–2017 compared with 2008-2012, 

The University of Bristol’s Atmospheric Chemistry Research Group played a key role in identifying the existence and source of these emissions, helping to address the crisis and uphold this important element of the UN’s climate change goals.

Work now continues to advance global capabilities in emissions monitoring. 

Identifying the source 

The research team led by Professor Matt Rigby worked in close collaboration with the Advanced Global Atmospheric Gases Experiment network to trace the origin of the emissions.

Measurements from stations in South Korea and Japan showed concentration spikes when plumes from neighbouring industrial regions passed by.

Using advanced atmospheric modelling that tracked pollution plumes, the team pinpointed northeastern China and specifically the provinces of Shandong and Hebei as the primary source. 

The findings also revealed that emissions from this region accounted for 40–60% of the global rise in CFC-11 levels, marking one of the first major breaches of the Montreal Protocol since its inception. 

Informing policy and enforcement 

The research had a direct and immediate impact on policymakers. Chinese authorities acted swiftly, identifying and shutting down illegal production facilities.

Enforcement actions included prosecutions and the seizure of banned ODSs. 

Further analysis by the Bristol team confirmed that emissions fell quicky by about 10,000 tonnes annually compared to the 2014–2017 period.

The timing of these reductions aligned closely with the research findings – a strong indicating that the publications were instrumental in driving China’s actions.

Overall, the reductions were equivalent to halting all annual CO₂ emissions from a city the size of London. 

Wider impact and future goals 

The team continues to monitor other ODS emissions, aiming to identify and address further breaches of international agreements that have been credited with the recovery of the Antarctic ozone hole. 

The Bristol team has also advanced global capabilities in emissions monitoring through the development of a unique greenhouse gas (GHG) and ODS observation network in the UK and Ireland.

This high-frequency measurement system, part of the UK DECC ((Deriving Emissions linked to Climate Change) Network, has made the UK one of the most densely monitored atmospheres globally.  

Other work at Bristol in this field has included the development a new satellite-based observation method to estimate India’s methane emissions, plus new, credible methods to avoid false accounting of GHG emissions from forestry in the EU.