For decades, the cold winter months in the Rocky Mountain high country kept the forest safe from insects, but rising temperatures and a fast-adapting beetle fueled a "perfect storm" in Colorado's alpine areas. Warmer winters have opened access to forests 2,000 feet higher than was previously possible. With so much new habitat available, the crafty pine beetle doubled its reproductive rate and learned to penetrate even the most insect-resistant trees. The result was nearly unprecedented forest devastation that approached 100 percent in some areas, turning great swaths of the alpine pine forest coppery brown.