One of the most visible and unintended consequences of global warming are bark beetles. Drought beget beetles. The U.S. is experiencing its worst drought in more than 50 years. The first 9 months of 2012 have been the warmest of any year on record in the contiguous U.S. These warm temperatures are fueling the largest tree-killing, bark beetle epidemic ever recorded throughout western North America.
Rising temperatures across western North America between 1.8 and 3.6 degrees Fahrenheit are having a deleterious affect on the conifer forests. These forests evolved to withstand temperatures in excess of minus 40 degrees Fahrenheit, and these frigid temperatures prevent bark beetle epidemics from occurring.
Global warming has effectively removed nature's cold-curtain enabling the indigenous mountain pine bark beetles to speed up their life cycles (formerly two years and now two generations within one year), and move-up into the high elevation forests throughout the western half of the continent.