Concentrations of carbon dioxide and other greenhouse gases in Earth’s atmosphere maintained their upward climb last year at a rate that not even the COVID-19 pandemic could dent, an international report has found.

The result, issued on Monday by the World Meteorological Organization, is evidence that the planet is veering ever further from realizing the climate goal of the Paris Agreement, which is to hold global warming to less than 2 C on average around the world.

For delegates heading to climate talks in Glasgow, Scotland, next week, the result is a reminder that countries will need to significantly improve efforts to reduce emissions in order to avert some of the more serious effects of climate change. Scientists have previously demonstrated that severe events, such as this past summer’s heatwave in the Pacific Northwest and flooding in Europe, can be attributed to the approximately 1 C of global warming that has already occurred since 1900.

Based on data gathered at 130 stations around the globe, including Canada, the new report is the latest in a series of annual snapshots of the state of greenhouse gases in the atmosphere. In hard numbers, it shows that the amount of carbon dioxide in the atmosphere reached 413 parts per million in 2020 and is growing at a rate of an additional 2.5 parts per million each year.

“It’s not just increasing, it has increased faster than the average within the last 10 years,” said Oksana Tarasova, who heads the meteorological organization’s global atmosphere watch program, based in Geneva, Switzerland.

Increases were also observed in concentrations of methane and nitrous oxide, the next two most abundant greenhouse gases. And while carbon dioxide emissions temporarily dropped by about 5.6 per cent last year, mainly because of COVID-19 lockdowns, the effect on total concentration level was virtually negligible, Dr. Tarasova said.

Collectively, the measurements put Earth on a track that diverges significantly from the 2 C target. Taking into account the latest assessment by the Intergovernmental Panel on Climate Change, released in August, Dr. Tarasova estimated that the current increase in concentration was more in line with 2.7 C of global warming.

“That will fuel a lot of extreme events and future changes in our system,” she added.

A continuous record of carbon dioxide levels in the atmosphere has been maintained since 1958 when observations began atop Mauna Loa in Hawaii. At that time, the concentration was about 315 parts per million. It has been on an increasingly steep upward track since then, apart from a seasonal cycle that is owing to plants taking up a bit more carbon dioxide when it is summer in the northern hemisphere.

Canada has been tracking carbon dioxide since 1975, when measurements began at Alert, Nunavut, at the country’s northern extreme. Nationally, more than 20 stations now conduct measurements of greenhouse gases using state-of-the-art optical sensors that are precise enough to distinguish between the characteristics of carbon dioxide that is emitted by the burning of fossil fuels from that which comes from natural sources.

Felix Vogel, a research scientist with Environment and Climate Change Canada who is based in Toronto, said the international measurements which Canada contributes to are anchored by a painstaking process of cross-checking and calibrating data from around the world to ensure accuracy.

And while he said this week’s result on carbon dioxide should not come as a surprise – since concentrations of the gas are so closely tied to energy use – he noted that the increase in atmospheric methane was an additional cause for concern.

“There’s somewhat of an acceleration in methane emission if you compare over the last decade,” he said. “And methane, specifically, is something that has very strong warming potential.”

In recent years, large methane leaks from oil and gas fields have become a target for a new generation of satellite and airborne surveys. However, these methods are unlikely to spot smaller leaks that are tied to local natural gas distribution or landfill sites.

“There’s really an impetus to try to get a handle on methane,” Dr. Vogel said, calling the effort a win-win because it reduces loss for suppliers. In the long run, he said, a concerted effort to reduce extraneous releases would be more likely to have a more lasting impact than a sudden, short-term reduction such as the one that occurred during the pandemic.

Dr. Tarasova added that significant reductions in both methane and nitrous oxide emissions, particularly in the oil and gas sector and in agriculture, could be achieved by making better use of available data even as countries continue to grapple with how to bring down emissions of carbon dioxide.

“There are plenty of solutions, but there’s no one solution that fits all because all economies are different,” she said.

Eddy Pérez, manager of international climate diplomacy for the Canadian Climate Network, an advocacy organization, said the latest results on greenhouse gases show how little room countries have to manoeuvre as they try to find a path forward.

“We’re at a point right now … where critically every tonne of emissions that we’re able to avoid has considerable impacts in how we prepare for a warming future,” he said.

The Globe and Mail, October 25, 2021