(NewsNation) — Scientists announced that the Doomsday Clock, the metaphorical measure of challenges to humanity, was reset to 90 seconds before midnight on Tuesday.

While the clock isn’t a forecasting tool, the Bulletin of the Atomic Scientists created it as a symbol in 1947 to shed light on how humanity’s actions are causing problems that could have mass consequences. 

“We are living in a time of unprecedented danger, and the Doomsday Clock time reflects that reality,” said Bulletin of the Atomic Scientists President and CEO Rachel Bronson. “Ninety seconds to midnight is the closest the clock has ever been set to midnight, and it’s a decision our experts do not take lightly.” 

The move, the closest to widespread calamity humanity has ever been judged to be, is “largely, though not exclusively” due to the war in Ukraine.

“Russia’s thinly veiled threats to use nuclear weapons remind the world that escalation of the conflict by accident, intention or calculation is a terrible risk,” Bronson said. “The possibilities that the conflict can spin out of anyone’s control remains high.”

The Bulletin evaluates the clock each January. This is the first full update since Russia’s invasion of Ukraine began last February, triggering a war in Europe and a new flood of refugees.

Biological threats such as the coronavirus pandemic, and disinformation are also contributing factors to the Doomsday clock change.

The clock created a stir after it was set to hit 100 seconds to midnight in 2020, which would have been the first time the famous clock had gone down to seconds rather than minutes.

The Bulletin only uses the clock to warn the world of dangers. The group said they are “not predicting the future.” Rather, the clock is a sort of analysis of international events, trends and public and official efforts to mitigate harm to humanity. 

“We look at data, as physicians look at lab tests and X-rays, and also take harder-to-quantify factors into account, as physicians do when talking with patients and family members.”