What is the Doomsday Clock and how does it work? - Sky News

After the US dropped atomic bombs on Hiroshima and Nagasaki at the end of the Second World War, members of the Bulletin saw a need to help the public understand the scale of the nuclear threat to the existence of humanity.

The clock moves closer or further away from midnight based on how the experts on the board, plus academic colleagues and the Bulletin's sponsors - which include 13 Nobel laureates - read threats at a particular time around the globe.

In a statement released by the Bulletin of the Atomic Scientists on Tuesday, its experts said: " Russia's thinly veiled threats to use nuclear weapons remind the world that escalation of the conflict by accident, intention, or miscalculation is a terrible risk."

The Bulletin's warning continued: "The invasion and annexation of Ukrainian territory have also violated international norms in ways that may embolden others to take actions that challenge previous understandings and threaten stability.

Artist Martyl Langsdorf came up with the idea of the clock and set the time to symbolise the dangers of nuclear confrontation, on the front cover of the Bulletin.

Since then it has been ticking away as political, nuclear and climate changes continued over the years, with experts revising the time up and down - mostly closer to midnight and its metaphor for total disaster.