Greenhouse gases in the atmosphere, the main driver of climate change, hit record highs last year and have continued climbing this year, despite measures to halt the Covid-19 pandemic, the UN said yesterday.

The World Meteorological Organization said lockdowns, border closures, flight groundings and other measures to rein in the coronavirus crisis had indeed cut emissions of many pollutants and greenhouse gases like carbon dioxide.

But it warned the industrial slowdown due to the pandemic had not curbed record concentrations of the greenhouse gases that are trapping heat in the atmosphere, raising temperatures, causing sea levels to rise and driving more extreme weather.

"The lockdown-related fall in emissions is just a tiny blip on the long-term graph," WMO chief Petteri Taalas said. "We need a sustained flattening of the curve."

The WMO's main annual Greenhouse Gas Bulletin said preliminary estimates indicated that during the most intense period of the shutdowns, daily carbon dioxide emissions may have been reduced by as much as 17 percent globally.

The annual impact was expected to be a drop of between 4.2 and 7.5 percent, it said. But this will not cause concentrations of CO2 in the atmosphere to go down, it said, warning the impact on concentrations was "no bigger than the normal year-to-year fluctuations."

CO2 is by far the most important long-lived greenhouse gas in the atmosphere related to human activities, and is responsible for roughly two-thirds of the Earth's warming.

"Carbon dioxide remains in the atmosphere for centuries and in the ocean for even longer," Taalas said.

"The last time the Earth experienced a comparable concentration of CO2 was three to five million years ago," he added, pointing out that at that time global temperatures were two to three degrees Celsius warmer and sea levels were 10-20 meters higher than now. "But there weren't 7.7 billion inhabitants," he said.

The second most prevalent greenhouse gas in the atmosphere is methane - emitted in part from cattle and fermentation from rice paddies - which is responsible for around 16 percent of warming.

AGENCE FRANCE-PRESSE

Concentrations of greenhouse gases are at a record high. AP

Greenhouse gas levels high amid virus shutdowns