"The hands of the Doomsday Clock remain at 100 seconds to midnight, as close to midnight as ever," Rachel Bronson, president of the Bulletin of the Atomic Scientists, said in a statement.

"The lethal and fear-inspiring Covid-19 pandemic serves as a historic 'wake-up call,' a vivid illustration that national governments and international organizations are unprepared to manage the truly civilization-ending threats of nuclear weapons and climate change," Bronson said.

The decision on setting the hands of the clock is taken by board members from the Bulletin of the Atomic Scientists, which was founded in 1945 by Albert Einstein and University of Chicago scientists who helped develop the world's first atomic weapons.

The board members include 13 Nobel laureates.

Created in 1947, the clock moved to 100 seconds to midnight in January of last year -- the closest to midnight it has been in its history.

It was originally set at seven minutes to midnight. The furthest it has ever been from midnight is 17 minutes, following the end of the Cold War in 1991.

Former California governor Jerry Brown, executive chair of the Bulletin of the Atomic Scientists, said it's "time to eliminate nuclear weapons, not build more of them.

"Likewise, with climate change: the US, China and other big countries must get serious about cutting lethal carbon emissions -- now," Brown said.

Susan Solomon, professor of environmental studies at the Massachusetts Institute of Technology (MIT), said "the pandemic-related economic slowdown temporarily reduced the carbon dioxide emissions that cause global warming.

"But over the coming decade fossil fuel use needs to decline precipitously if the worst effects of climate change are to be avoided," Solomon said.

Former Liberian president Ellen Johnson Sirleaf said the Covid-19 pandemic "is a terrible warning against complacency in the face of global threats to all human life.

"It is only through collective action and responsible leadership that we can secure a peaceful and habitable planet for future generations," she said.

The Bulletin members recommended that the United States and Russia extend the New START nuclear treaty and that the US return to the nuclear deal with Iran.

They also urged governments, technology giants and media organizations to cooperate on finding "practical and ethical ways to combat internet-enabled misinformation and disinformation."