Greenhouse gas concentrations in the atmosphere have continued to increase during 2020 despite unprecedented falls in emissions driven by the coronavirus pandemic.
Carbon dioxide levels saw significant growth in 2019 with the annual global average breaching the threshold of 410 parts per million with this rise continuing into 2020.
The Global Carbon Project estimated that during the most intense period of the shutdown, daily CO2 emissions may have been reduced by up to 17 per cent globally, but the prediction of the total annual emission reduction over 2020 is very uncertain.
It offered a preliminary estimate of a drop somewhere between 4.2-7.5 per cent, although economies could bounce back in 2021 if the virus is brought under control, potentially undoing much of the reduction seen this year.
“Carbon dioxide remains in the atmosphere for centuries and in the ocean for even longer. The last time the Earth experienced a comparable concentration of CO2 was 3-5 million years ago, when the temperature was 2-3°C warmer and sea level was 10-20 metres higher than now. But there weren’t 7.7 billion inhabitants,” said WMO secretary-general Professor Petteri Taalas.
“We breached the global threshold of 400 parts per million in 2015. And just four years later, we crossed 410ppm. Such a rate of increase has never been seen in the history of our records. The lockdown-related fall in emissions is just a tiny blip on the long-term graph. We need a sustained flattening of the curve.”
He added that the pandemic could still be used as a platform to launch sustained climate change action through systemic changes designed to promote low-carbon economies.
The WMO made specific mention of fossil fuel combustion, cement production and deforestation as major contributors to 2019’s record CO2 levels.
During the last decade, about 44 per cent of CO2 remained in the atmosphere, while 23 per cent was absorbed by the ocean and 29 per cent by land, with 4 per cent unattributed.
Earlier this month, scientists theorised that global temperatures could continue to rise for centuries even if climate goals to cut human-induced greenhouse gases to net zero are successful.