Researchers have identified another unwanted effect of global warming: bigger and itchier poison ivy(ツタウルシ). Scientists conducted experiments in a forest at Duke University, increasing carbon dioxide levels to those expected in 2050. The atmospheric conditions caused poison ivy plants to produce more-- and a more allergenic form-- of its rash(発疹)-causing chemical, urushiol(漆の主成分). The vines(つる) also grew to about three times the size of those grown in normal atmospheric conditions.