The narrow, towering lodgepole pine trees that populate North America's western forests may disappear in the coming decades due to climate change and attacking beetles, a study said Monday. The trees are tough and adaptable, particularly in areas prone to wildfires and bitter cold, but warmer, dryer seasons and pests are combining to kill off the trees in growing numbers, US and Canadian researchers say. By the year 2020 the trees in the Pacific Northwest will have declined about eight percent, and then "continued climatic changes are expected to accelerate the species' demise," said the study in the journal Climatic Change. "By 2080, it is projected to be almost absent from Oregon, Washington and Idaho," it said. The tall, straight trees were once harvested for making American Indians' teepee tents and have been used widely in building poles and fences, as well as providing habitat for large animals in the wild. "For skeptics of climate change, it's worth noting that the increase in vulnerability of lodgepole pine we've seen in recent decades is made from comparisons with real climatic data, and is backed up with satellite-observations showing major changes on the ground," said Richard Waring of Oregon State University. "This is already happening in some places," Waring said. "Bark beetles in lodgepole pine used to be more selective, leaving the younger and healthier trees alone. "Now their populations and pheromone levels are getting so high they can more easily reach epidemic levels and kill almost all adult trees," he said. However, the lodgepole pine is expected to survive in the upper elevations of Yellowstone National Park and a handful of other locations, the study said. The research was funded by NASA and the Natural Sciences Engineering and Research Council of Canada.