Time Magazine: One of the few potentially positive effects of climate change, at least in the short term, is that increased concentrations of carbon dioxide in the atmosphere may enhance the growth plants. That could be good for agriculture — though warming temperatures and changing rain patterns in a warmer world might wipe out that advantage. But there are no unalloyed gifts from climate change. Recent research suggests that global warming will also exacerbate respiratory allergies, as higher CO2 …