资源环境科技发展态势分析平台

By Adam Vaughan

David McNew/Getty Images

Global carbon emissions are likely to see their steepest fall this year since the second world war, according to researchers who say coronavirus lockdown measures have already cut them by nearly a fifth. But the team warns that the dramatic drop won’t slow climate change.

The first peer-reviewed analysis of the pandemic’s impact on emissions predicts they will fall between 4.2 and 7.5 per cent on last year. A rise of around 1 per cent had been expected for 2020 before the crisis.

“In terms of a relative drop, you’d have to go back to the first half of the last century, around WWII. Certainly, in modern times, this is an unprecedented drop,” says Glen Peters at the Center for International Climate and Environmental Research in Norway.

Analysing the data up to 7 April, the researchers found that restrictions imposed around the world had cut daily emissions by 17 per cent versus the daily average for 2019. This only takes the world back to 2006 levels, a sign of how much emissions have grown in recent years.

The reductions have been fairly uniform globally, with a drop of 1048 million tonnes of CO2 in the first four months of the year. Peters and his colleagues expect an annual fall of 1524 MtCO2 if pre-pandemic conditions return by mid-June, or 2729 MtCO2 if some restrictions are in place until the year’s end.

However, the team cautions that the precipitous drop will make little dent in future global warming.

“If emissions go down 5 per cent this year overall, given that climate change is a cumulative problem, it basically makes no difference at all,” says Peters. He calculates that a 5 per cent drop would be equivalent to 0.001°C less warming, a minuscule amount with the world on course for at least 3°C of warming. The UK Met Office expects a tiny dip in atmospheric CO2 levels this year, but projects that they will still be the highest in at least 2 million years.

A report last year found that emissions must fall by 7.6 per cent every year this decade to meet the Paris Agreement’s goal of checking warming at 1.5°C. The question of whether governments support green measures or fossil fuel industries with covid-19 recovery packages will be key to determining future emissions. A 1.4 per cent emissions drop in the financial crash of 2009 was wiped out by an above-average increase the following year.

The new study follows one last week, not yet published in a journal, which observed that carbon emissions dropped 58 per cent in London during lockdown, with big falls seen in other European cities too.

Journal reference: Nature Climate Change, DOI: 10.1038/s41558-020-0797-x

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