Humans in northern Europe 700,000 years ago

The discovery of flint tools in northern England from “a time when England's climate was warm enough to be the home of lions, elephants and sabre-tooth tigers” indicates that humans at least visited the area 700,000 years ago.

Jim Rose, a professor at the University of London who also was involved in the study, said that 700,000 years ago England was still connected to the European mainland and enjoyed periods of balmy weather between the time that massive glaciers swept through the area, freezing and reforming the landscapes.

During such thaws, he said, early humans would have been able to migrate from the Mediterranean to England, where there were mild winters, flat landscapes and major rivers.

Rhinoceroses, elephants, sabre-tooth tigers, lions, hippopotamuses and bears lived in the area at the time. The scientists said they don't know whether the humans used the newly discovered tools to kill animals for food, or merely to scavenge from carcasses that predators left behind.

Now, why was it so warm back then? Global warming? The article doesn’t say as it focuses upon the surprising adaptability of early humans.