The Bulletin of Atomic Scientists on Thursday said they had placed the Doomsday Clock at two-and-a-half minutes to midnight, 30 seconds closer to the end of civilisation than its previous position. The new setting in the Doomsday Clock – a symbolic countdown to the end of the world – is the closest it has been to midnight since 1953, when the US and the former Soviet Union tested their first thermonuclear weapons.

In an opinion piece for The New York Times, the group said that the international community in 2016 had “failed to come effectively to grips with humanity’s most pressing existential threats, nuclear weapons and climate change”. “Making matters worse, the United States now has a president who promised to impede progress on both of those fronts,” theoretical physicist LM Krauss and retired US Navy Rear Admiral David Titley said. “Never before has the bulletin decided to advance the clock largely because of the statements of a single person.”

Donald Trump has so far made “ill-considered comments” regarding the US’ nuclear arsenal and has also “expressed disbelief” in the consensus on global warming, Krauss and Titley said. “And his nominees to head the Energy Department, the Environmental Protection Agency and the Office of Management and the Budget have disputed or questioned climate change.”

The two added that while the need for leadership to protect the global population from climate change and nuclear weapons had intensified, people had instead faced “inaction and brinksmanship”. Global security concerns included North Korea’s nuclear weapons development, modernisation of weapons by all nuclear-armed countries and the “simmering tensions between India and Pakistan”, they wrote in The New York Times.

The clock, which has been in operation since 1947, has been placed at various intervals between two minutes and 17 minutes since its inception.