risks

Significant risks to humanity can be:

A nuclear war by accident would be particularly serious, risk and consequences:

The probability of an accidental nuclear war occurring in the next 20 or 30 years is not negligible, but may be very high as a result of climate change, among other things.
In such a case, many nuclear weapons would probably be used.
The consequence could be a nuclear winter with devastating consequences, especially with regard to food security for the entire planet. Possibly the survival of the entire human race would be threatened.

See also the quotation and the comments at the menu item “Nuclear War Risk“

On possible interactions between climate change and nuclear war risk: https://www.fwes.info/akav-klima-20-1-en.pdf