Global CO2 emissions mainly caused by burning fossil fuels are set to rebound in 2021 to levels seen before Covid, according to an assessment published on November 4 that served as a “reality check” to vague decarbonisation pledges at the UN’s COP26 climate summit.

Overall, CO2 pollution this year will be just shy of the record set in 2019, according to the annual report from the Global Carbon Project consortium.

Capping the rise in global temperature to 1.5 degrees Celsius above pre-industrial levels – as per the Paris Agreement – would limit mortality and damage, but achieving that goal would require slashing carbon emissions nearly in half by 2030 and to net zero by 2050, the UN’s climate science authority warned.

Carbon pollution from oil remains well below 2019 levels, but could surge as the transport and aviation sectors recover from pandemic disruption, said the study in the journal Earth System Science Data.

The findings indicate that future C02 emissions could eclipse the 40-billion tonne record set in 2019, which some have predicted – and many hoped – would be a peak.

Twenty-three countries accounting for a quarter of global emissions over the last decade – including the US, Japan, Germany, France and Britain – saw significant declines in emissions.

International Institute for Environment and Development director Peter Norton said the report showed that on current emissions levels the world would emit enough to breach the 1.5C goal within 11 years.