Heat-trapping gas levels reach a new record high, despite the coronavirus lockdown

While carbon emissions fell during the spring lockdown, the drop amounted to little more than “just a tiny blip on the long-term graph” and will not have any meaningful effect on the atmospheric concentrations of greenhouse gases, the WMO said in its annual Greenhouse Gas Bulletin.

Under the Paris Agreement, the vast majority of nations agreed to limit global warming to below 2 degrees Celsius above pre-industrial levels and to pursue efforts to limit it to 1.5 degrees. To reach that goal, greenhouse emissions need to drop dramatically and soon. The United Nations calculated last year that to stay within the 1.5 degrees limit, emissions would need to fall by 7.6% each year between 2020 and 2030.

Carbon dioxide occurs in atmosphere naturally — without it, the Earth would be too cold to sustain life. It cycles through the atmosphere into organisms and back, keeping the system in balance. The problem is that human activities — mostly the burning of fossil fuels — have added a lot more carbon dioxide into the system, far more than can be absorbed. And according to the WMO, the lockdown-induced drop in man-made emissions is smaller, or at most similar in size to natural fluctuations and so won’t make any difference in the long term.

It’s a bit like filling a bathtub. While the water is pouring in a little slower this year, the bathtub will continue to fill up as long as there’s more water pouring in than draining out.

The amount of carbon dioxide in the atmosphere fluctuates naturally — but over much, much longer periods of time than currently seen. By studying air bubbles trapped deep in ice cores, scientists know that until humans started burning fossil fuels some 300 years ago, the level of carbon dioxide hadn’t exceeded 300 parts per million for about a million years. The amount of carbon dioxide in atmosphere is now nearly 50% higher than in 1750, according to the WMO.

“Carbon dioxide remains in the atmosphere for centuries and in the ocean for even longer,” Professor Petteri Taalas, the WMO secretary-general, said in a statement. “The last time the Earth experienced a comparable concentration of [carbon dioxide] was 3-5 million years ago, when the temperature was 2-3°C warmer and sea level was 10-20 meters higher than now. But there weren’t 7.7 billion inhabitants.”

The amount of methane, a less common but more potent greenhouse gas, has also risen in the past year. Its concentration in the atmosphere is now more than 2.5 times what it was before the industrial revolution. About 60% of methane that is emitted into the atmosphere comes from human activities — mostly agriculture, fossil fuel exploitation, landfills and biomass burning.