ABC: Climate changes and rising carbon dioxide levels don't just affect the environment. Experts say they also affect your nose. Warmer temperatures and higher carbon dioxide levels mean certain plants will thrive, and those are the plants that tend to make us sneeze during allergy season. Allergies may seem like a minor nuisance, but according to the CDC there are an estimated 50 million Americans living with allergies, and $18 billion is spent every year dealing with the affliction. From hay fever...