Chicago Sun-Times: If you have respiratory allergies, you have an environmental problem: Something in the air is making you sniffle, sneeze, feel stuffed up or wheeze. And growing evidence suggests your problem might be linked with the biggest environmental problem of all: global climate change. That could be especially true for pollen sufferers. Tree, grasses and weeds — including the ragweed tormenting many people right now — churn out more pollen over more weeks when temperatures and carbon …