Global climate models from Germany (green), Canada (red) and USA (black) scaled to the Kenai predict that post-2030 mean summer temperatures will always be above the threshold for spruce bark beetle outbreaks. Observed temperatures are from the Homer airport since 1932. Lower bar graph shows annual beetle-kill for southern Kenai since aerial surveys began in 1971 (US Forest Service). Ed Berg graphic.
The article (URI below) appeared in the Kenai National Wildlife Refuge’s Refuge Notebook series.
http://www.fws.gov/uploadedFiles/Region_7/NWRS/Zone_2/Kenai/Sections/What_We_Do/In_The_Community/Refuge_Notebooks/2015_Articles/Refuge_Notebook_v17_n37.pdf