Global CO2 emissions from fossil fuels are set to fall by up to 7% in 2020 as a result of the coronavirus pandemic, but even this dramatic decline, the sharpest since the Second World War, would barely deter long-term global warming, researchers reported on Tuesday.
At the beginning of April, coronavirus lockdowns led to a 17 % reduction in carbon pollution worldwide compared to the same period last year, according to the first peer-reviewed assessment of the pandemic impact on CO2 emissions published in Nature Climate Change.
Four countries or blocs, China, the United States, the European Union and India, accounted for two-thirds of the decline of more than one billion tons of CO2 in the first four months of 2020.
Total emissions from industry and energy last year amounted to a record 37 billion tonnes.
"Population confinement has led to drastic changes in energy use and CO2 emissions," said lead author Corinne Le Quere, a professor at the Tyndall Centre for Climate Change Research at the University of East Anglia.
"These extreme decreases are likely to be temporary, however, as they do not reflect structural changes in the economic, transport or energy systems."
If the global economy recovers to pre-pandemic conditions by mid-June, an unlikely scenario, CO2 emissions are projected to fall by only four % in 2020, according to Le Quere and her team.
But if lockdown restrictions persist throughout the year, the decline will be around 7%.
With nearly five million confirmed infections and 320,000 deaths, the COVID-19 pandemic deflected attention from the climate crisis that dominated global concerns in 2019.
But the threat to the climate remains, other experts warn.
"This will make barely a dent in the ongoing build-up of carbon dioxide in the atmosphere," said Richard Betts, head of climate impacts research at Britain's Met Office Hadley Centre.
Like filling a bathtub - "We need to stop putting it there altogether, not just put it there more slowly," he said.
"It's like we're filling a bath and have turned down the tap slightly , but not turned it off. The water is still rising, just not as fast."
So far, the average surface temperature of the Earth has risen by one degree Celsius above pre-industrial levels, enough to amplify deadly droughts, heat waves and superstorms engulfed by rising seas.
Under the Paris Climate Treaty of 2015 , nearly 200 nations pledged to reduce global warming to "well below" 2C.
But the UN Intergovernmental Panel on Climate Change (IPCC) has subsequently determined that 1.5C is a much safer temperature guard.
The pandemic has highlighted how difficult it will be to meet that more ambitious target.
Scientists conclude that emissions will fall by 7.6%, in line with the worst-case lockout scenario for 2020, this decade per year to maintain the 1.5C limit, unless other ways of eliminating carbon from the atmosphere are found.
"The pandemic has shown us that major structural changes in the transport and energy systems are required," noted Mark Maslin, a professor of climatology at University College London.
Some experts have suggested the pandemic could speed up that transition.
"Fossil fuels seem to be getting hit harder relative to renewables," Glen Peters, research director of the Center for International Climate Research in Oslo, told AFP.
Sectors hit unevenly - "If this (continues) we may come out of COVID with emissions going down, since renewables have been able to take more relative space, pushing out some of the most polluting fossil fuels, especially coal."
But the multi-trillion dollar bailout packages, particularly in the U.S. and China, hastily assembled to stave off another Great Depression send mixed signals when it comes to building a green global economy.
"There is a high risk that short-sightedness will lead governments to lose track of the bigger picture and put money into highly polluting sectors that have no place in a zero-carbon society," said Joeri Rogelj, a researcher at Grantham Institute and Imperial College London.
Various sectors of the economy have been affected unevenly by the measures taken to stop the pandemic, the study revealed.
On 7 April, the day that global CO2 pollution decreased the most, land transport emissions accounted for more than 40% of the decrease, while industry, electricity generation and aviation accounted for 25, 19 and 10% respectively.
Calculation of global emissions of CO2 and methane, another potent greenhouse gas, usually takes months or longer, but the methods used in the study could help guide decision-making, the authors said.
"If we can see the effect of a policy in the space of months as opposed to years then we can refine policies more quickly," said Peters.
