Washington Post: A significant amount of the climate change caused by greenhouse gas emissions in the past century has been hidden from us, scientists say -- by another type of pollution that actually cools the climate and temporarily cancels out some of the warming. Two new studies, both released today in the journal Nature Geoscience, address the powerful influence of aerosols -- fine particles or drops of liquid often released by industrial activity -- on the climate, and suggest that as nations around the world...