Concentrations of climate-warming carbon dioxide into the atmosphere have peaked despite a drop in emissions during the Covid pandemic, scientists said.
The latest measurements from the Long Recording Station at Mauna Loa Observatory, Hawaii, show that global levels of carbon dioxide are 50% higher than they were when the Industrial Revolution began in Britain.
The data released by the Scripps Institution of Oceanography, University of San Diego, California, shows that greenhouse gas concentrations averaged 417.14 parts per million (ppm) in March, a new record high.
The UK Met Office predicts monthly concentrations of carbon dioxide, which is the biggest cause of rising temperatures and the climate crisis, will peak in 2021 at around 419.5 ppm.
The previous record for monthly carbon dioxide concentrations at Mauna Loa in the Scripps dataset was 417.10 ppm in May 2020.
Last year’s average annual figure was 413.94 ppm – with the forecast of 2021’s level around 416.3 ppm.
Carbon dioxide levels in the atmosphere fluctuate slightly during the year and decrease as some are absorbed during spring and summer by plants growing in the northern hemisphere, before rising again in autumn and winter.
But the long-term trend in rising concentrations of carbon dioxide is caused by human activities, mainly through the burning of fossil fuels and also through deforestation, the Met Office said.
Global emissions have temporarily declined in 2020 due to a decline in the use of transportation and economic activity as the coronavirus pandemic struck.
But the reduction in emissions in 2020 was not enough to significantly affect the build-up of carbon dioxide in the atmosphere, which is still rising.
The Met Office warned that much larger, long-term reductions in emissions are needed to slow or stop the rise.
According to projections by the UN’s climate science body, the Intergovernmental Panel on Climate Change, global emissions should reach net zero by around 2050, or earlier, to halt global warming at 1.5C – from which the worst effects of rising temperatures are expected.
Reaching net zero involves reducing emissions to as close to zero as possible and taking steps such as planting trees to absorb the remaining pollution.
Prof Martin Siegert, of the Grantham Institute, Imperial College London, commented on the latest data and said the new record height is completely expected.
‘Emissions may have been reduced, but we still emit a lot of carbon dioxide, so the atmospheric concentration is likely to rise – and it will continue until we get somewhere near net emissions.
“Our path to net zero is obvious, challenging and essential – and we need to make the transition urgently,” he said.
Prof Simon Lewis, of University College London, said: ‘It is easy to forget how much and how fast fossil fuel emissions affect our planet.
‘It took more than 200 years to increase the amount of carbon dioxide in the atmosphere by 25%, and just 30 years to reach 50% above the pre-industrial level. This dramatic change is like a human meteorite hitting the Earth. ”
But he added: “If countries now make plans to put society on a path of sustained and dramatic emissions cuts from today, we can still avoid rising emissions and the dangerously accelerated effects of climate change.”