Environment

Climate Change Killing the World's Oldest Trees

These ancients were around when ancient Sumerians scratched their cuneiform on clay tablets, and they were standing when Alexander the Great swept across Asia. They bore witness to both the rise and fall of the Roman Empire, survived Columbus' colonization of the New World, and saw the birth and expansion of the United States.

But now, because of climate change, the oldest trees on the planet may be facing their eventual extinction, a new study suggests.

Ancient bristlecone pines (Pinus longaeva), which thrive in the upper reaches of the White Mountains in California, could be supplanted by younger trees from an upstart species as temperatures warm and baby trees begin to grow higher on the mountain.

The world's oldest genetically unique trees reside just below the tree line, where the scant rainfall, frigid air, and rocky limestone soil eliminates all but the hardiest of species. From about 9,500 to 11,500 feet (2,900 to 3,500 meters), bristlecone pines dominate the landscape. In the few patches with sandier, more granite-like soils, native limber pine trees (Pinus flexilis) cluster, according to the statement.

The oldest individual tree in the world is a 5,062-year-old P. longaeva in the White Mountains, and the second-oldest tree, dubbed Methuselah, is also a Great Basin bristlecone pine living nearby.

Above the tree line, temperatures are too cold to support trees, but global warming has shifted the tree line higher up the mountain. Because temperature typically governs where trees live, that would ordinarily mean that trees such as the bristlecone pine would simply start growing at higher altitudes.

Most of the baby trees colonizing the higher altitudes above the tree line appear to be limber pines, the researchers found. It turns out that limber pines got an assist from the Clark's nutcracker, a local bird that munches on and disperses the trees' seeds. This process speeds up how quickly limber pines can colonize new locations, the study found.