The musician-turned-activist reckons the world will end in 2030 - leading to the extinction of humankind.
Sir Bob, 61, based his miserable prediction on the effects of climate change.
“The world can decide in a fit of madness to kill itself," he told a group of youngsters at a summit in Johannesburg, South Africa.
The former Boomtown Rats singer also warned "the next war will not be a World War One or a World War Two, it will be the end."
He added: "We may not get to 2030. We need to address the problem of climate change urgently."
Sir Bob is best-known for his attempts in helping to fight famine in Africa, staging Live Aid at Wembley Stadium in 1985.
He finished his speech by apologising for being "bloody miserable", but added: "just get on with it".
Check out the picture used in the article.......
Isn't that steam/water vapor....non polluting steam?