 Canada. Parry visits the village of Old Crow, just inside the arctic Circle and the Yukon's northernmost community. although the village has no road access, it is located on an ancient natural highway, and each spring almost 200,000 caribou (above) pass close by as they migrate north to their summer calving grounds. For the Gwich'in people the migration has formed a vital part of their existence for centuries, but global warming is affecting the rhythm of the migration and they fear that oil companies will soon invade the calving grounds. Next he heads to Northern alberta, where another native people tell how oil has changed their way of life for ever. Mike Bradley