Mother Jones
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In 1996 Colorado received a very unwelcome—and hungry—house guest, the mountain pine beetle, whose voracious appetite for pine has since killed off millions of acres of trees there. A few years later, the beetles came knocking in British Columbia and have now knocked out over half the province’s pine timber. The full-bore invasion of these critters, each no bigger than a grain of rice, is now one of the most pressing ecological disasters in the West, and their spread, scientists believe, is driven by climate change.
The beetles aren’t alone: Rising equatorial temperatures have pushed a menagerie of pests north at an alarming rate of nearly 10,000 feet every year since 1960, according to a new survey out today in Nature. Researchers led by biologist Dan Bebber at the UK’s University of Exeter combed through databases hosted by the non-profit CABI, which aggregates scientific and trade literature on agriculture, for the first documented appearance of over 600 kinds of pests (including insects, fungi, viruses, and bacteria), over a 50-year period in the Northern Hemisphere. They found, averaged across 14 taxonomic groups, a distinctive northward migration, wherein species first noticed at southern latitudes were, at a later date, discovered anew at northern latitudes.
The chart below, from the paper, shows the distribution range of the different pest groups Bebber examined, with the vertical axis indicating distance from the equator (positive distances indicate north; negative distances indicate south) and the horizontal axis indicating time, from 1960 to the present. Overall, the groups show a gradual northward migration over time (up and to the right):
Bebber et al.
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