Air conditioning systems are significant contributors to global warming, and replacing them with more efficient systems could have a big impact, according to a new UN report.

An estimated 3.6 billion cooling appliances are in use globally today, and that number is growing by up to 10 devices every second, the report says. To make matters worse, most air conditioning units use hydrofluorocarbons (HFCs), which are potent greenhouse gases.

Without policy intervention, emissions from air conditioning and refrigeration are projected to rise 90% above 2017 levels by 2050. Among the possible solutions are measures to encourage implementation of cooling retrofits and passive technologies.

Rebates and incentives to promote cooling efficiency in the built environment could also have a significant impact as would financial support to develop new cooling technologies.