Learned Butcher please humour me. So thousands of years ago...

Learned Butcher please humour me. So thousands of years ago there was an ice age where the planet was covered with ice.
Humans habits in those days can't be blamed for melting all the ice however I guess they would have
had big campfires to keep them warm and cook their mammoth steaks. Whatever caused it to melt ??? The earth started warming
and it has continued to do so and will continue to do so.
What is wrong with my theory ????