The daily global CO₂ output has at times decreased by about one sixth at the peak of the strict corona measures. At the beginning of April, global daily values were estimated to be up to 17 percent lower than the 2019 average, according to an international research team reported in the journal Nature Climate Change.
According to the climate scientists led by Corinne Le Quéré from the University of East Anglia in England, on 7 April an estimated 83 megatonnes were emitted worldwide CO₂ as a result of the burning of fossil fuels and cement production - in 2019 the daily average was 100 megatonnes. In some countries, emissions had even fallen by up to 26 percent on average at the height of the corona restrictions.
The precautions taken by governments to prevent the spread of the Sars-CoV-2 pathogen have had a major impact on energy demand around the world, the researchers write. The fact that large parts of the world's population had to stay at home and borders had been closed has reduced traffic and changed consumer habits. On 7 April, emissions from land and air transport alone were 36 and 60 percent lower respectively than the annual average for 2019, meaning that land transport, energy and industry together accounted for 86 percent of the total CO₂ decline.
Emissions in the first four months of the year are estimated to have fallen by a total of around 1048 million tonnes. The decline was particularly strong in China (minus 242 megatonnes), the USA (minus 207 megatonnes) and Europe (minus 123 megatonnes). Worldwide, the total reduction compared with the months January to April 2019 was around 8.6 percent.
Le Quéré explains that these sharp declines are probably only temporary, as they do not imply structural changes in the economy, transport or the energy sector. Her colleague Glen Peters from the Cicero Centre for International Climate Research in Oslo adds: "The emission reductions resulting from Covid-19 will clearly be unprecedented. Less certain is how the economy will recover in late 2020 and in 2021. There is also great uncertainty about how the pandemic will develop and what restrictions will be necessary for the rest of the year and beyond.
If activity around the world reaches pre-corona levels by mid-June, the researchers expect annual emissions to fall by an estimated four percent in 2020. If, on the other hand, some restrictions remain in place until the end of the year, the reduction should be around seven percent.
For the study, Le Quéré's team looked at data from 69 countries, 50 US states and 30 Chinese provinces that were available by the end of April. Institutions from seven countries were involved, including the Berlin-based climate research institute MCC (Mercator Research Institute on Global Commons and Climate Change).