The Doomsday Clock, a symbolic timepiece showing how close the world is to ending, has been moved forward to 90 seconds to midnight, the closest it has ever been to the theoretical point of annihilation.

A statement from Bulletin of the Atomic Scientists on Tuesday said the war in Ukraine was the main — although not the sole — reason for the move.

A board of scientists and other experts in nuclear technology and climate science, including 13 Nobel laureates, discuss world events and determine where to place the hands of the clock each year.

The clock was last moved in 2020, when it was set to 100 seconds from midnight, the first time it moved past the two minute mark since its creation. The hands of the clock are moved closer to, or further away, from midnight based on the scientists’ reading of existential threats at a particular time.

Climate change and disinformation also contributed to the setting of the new time.

The clock was created in 1947 by a group of atomic scientists, including Albert Einstein, who had worked on the Manhattan Project to develop the world’s first nuclear weapons during the Second World War.

The clock started ticking, more than 75 years ago, at seven minutes to midnight.

At 17 minutes to midnight, the clock was furthest from doomsday in 1991, as the Cold War ended and the United States and Soviet Union signed the Strategic Arms Reduction Treaty that substantially reduced both countries’ nuclear weapons arsenals.

Critics have dismissed it as fearmongering, or questioned its usefulness and the methodology. In a 2015 essay, a University of Oxford researcher in global catastrophic risk cast doubt on the clock as a measurement of “actual risk,” writing that it was more a reflection of the “strong feeling of urgency” about the risks among the team who operate it.

With files from Reuters and The Washington Post