Yale Environment 360: Land disturbances, such as agricultural practices and development, may have a big impact on snow purity and melt rates, according to a large-scale survey of impurities in North American snow by researchers at the University of Washington. During a nearly 10,000-mile trek across North American snowfields, the researchers were particularly interested in the Bakken oil fields of northwest North Dakota. Before undertaking the study, they predicted that diesel emissions and air pollution associated with...