A newe study looked at five of the most problematic invasive weeds in the arid Western U.S. The conclusion: global warming will force three of them to retreat. But two, including the hated and prickly yellow starthistle, will expand their range northward as winters get warmer. They also have tolerance for deep drought. The other winner: tamarisk.
The three loser weeds: spotted knapweed, cheatgrass and leafy spurge. They're likely to shift towards cooler regions, reducing greatly the area under threat.