Poison Ivy - Thanks to Global Warming
Courtesy of the USDA - we have this bit of research that points out that under increased levels of CO2 - poison ivy will grow much faster (invasive plants with underground storage parts respond dramatically to increased Carbon Dioxide levels) and will become much bigger in leaf suface.
This particular link (click the title) is hard to read in html - I suggest you read the power point presentation if you really want to see the data on other weed problem increases under global warming. (Can you Southern gardeners say Kudzu?)
If you don't want to take the time to read it - weeds love CO2 as much as the next plant (that's the bottom line).