Sarah James, an Alaska Native elder, says global warming is radically changing her homeland. Even the forests no longer grow straight. Melting ground has caused trees to tilt or fall.

"Because permafrost melts, it causes a lot of erosion," says James, who lives in Arctic Village, a small Native American village in northeastern Alaska. "A lot of trees can't stand up straight. If the erosion gets worse, everything goes with it."

Permafrost is permanently frozen ground. But climate change has caused much of that ground to melt at an unprecedented rate. The ground buckles and sinks, causing trees to list at extreme angles.

Sometimes the trees survive the stress and continue growing, uprighting themselves to vertical. Other times they collapse or drown from