GENEVA: Greenhouse gases in the atmosphere, the main driver of climate change, hit record highs last year and have continued climbing in 2020 despite measures to halt the Covid-19 pandemic, the UN said Monday. World Meteorological Organization (WMO) chief Petteri Taalas meanwhile welcomed several countries' vows to focus on climate-friendly technologies as they seek to revive their economies after the coronavirus crisis.

Speaking to journalists, he also voiced optimism at US president-elect Joe Biden's pledge to return his country to the Paris climate accord, saying he hoped it "might have the domino effect (and) motivate also some other countries." But the United Nations agency dashed notions that the lockdowns and other measures to rein in the pandemic could by themselves repair some of the damage of ever-growing greenhouse gas emissions in recent decades.

While emissions have shrunk this year, the WMO warned this 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," Taalas said.

The WMO's main annual Greenhouse Gas Bulletin said preliminary estimates pointed to daily carbon dioxide (CO2) emissions falling by as much as 17 percent globally during the most intense period of the shutdowns. 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 concentrations will continue to rise, albeit at a slightly reduced pace, the WMO said, adding that the pace would be no more than 0.23 parts per million (ppm) per year slower than the previous trajectory - well within the 1.0 ppm natural inter-annual variability.