The bristlecone pine is the oldest species of tree on the planet, and it may be facing extinction. The trees thrive in California's White Mountains, and are living records of ancient history. The trees grow at a glacial pace, adding just one inch of girth a year. This slow growth combined with their geographic positioning, away from the competition of other trees or parasites, has allowed the species to live for extended periods of time. Currently, the oldest living bristlecone pine is 5,062 years old.
Global warming has created new climatic conditions for the pines, which they have been forced to adapt to. As global temperatures rise, trees in the White Mountains have started to migrate to higher elevations, which were previously too cold for their survival but now provide ideal temperatures. The bristlecone pines face competition from limber pines which have been able to higher altitudes in greater numbers because of the Clark's nutcracker – a bird that has been dispersing the trees' seeds.