ONE day, climate change could cost the earth. For now, it is a nice little earner for Russian hunter Alexander Vatagin.

In Siberia's northernmost reaches, well above the Arctic Circle, the changing temperature is thawing the permafrost to reveal the bones of prehistoric animals such as mammoths, woolly rhinos and lions that have lay buried for thousands of years.

Private collectors and scientific institutes will pay huge sums for the right specimen, and bone prospectors such as Mr Vatagin have turned this region, eight time zones from Moscow, into a paleontological Klondyke.

"Last year someone was paid 800,000 roubles ($36,755) for a mammoth head with two tusks in great condition," Mr Vatagin said.

Prehistoric bones are easy to spot. The permafrost is thawing so rapidly that in certain places in the tundra, bones poke through the soil every few metres. Some lie on the surface.

"From the point of view of humanity, it would have been better if this had never happened."