Alaskan people tell of climate change
Now they have discovered a rich new source of records extending their knowledge back by decades through the oral history of native Alaskans.
Barrow is the most northerly town in the United States, lying 300 miles inside the Arctic Circle.
And 92-year-old Bertha Leavitt is its oldest inhabitant.
"When I was a child", she says, "it was so much colder and the winds in winter used to be fierce." She remembers her elders telling in their stories that the weather was going to change. And since her childhood she believes this has come true.