A thousand-year freeze that began in 11,000 B.C. may have been caused by thousands of atomic-force chunks from a disintegrating comet, a British scientist said.

The fragments, each hitting with the force of a 1-megaton nuclear bomb, triggered fires that covered whole continents and filled the atmosphere with smoke and soot that blotted out the sun, said Bill Napier, a professor at Cardiff University Astrobiology Center.

Napier said Earth may have strayed into a dense trail of fragments being shed by a large comet.

The resulting freeze caused glaciers to advance, disrupted human cultures and wiped out an estimated 35 families of North American mammals, The Daily Telegraph reported Friday.

There is "compelling evidence" the main comet has been breaking apart ever since, leading to meteor streams known as the Taurid Complex, Napier wrote in the journal Monthly Notices of the Royal Astronomical Society.