Sierra Club plans to sue Minnesota Power over pollutants at coal plants
"The Sierra Club’s claims are based on opacity, which measures the thickness of emissions from a smoke stack by how much light passes through it, the AP says. Minnesota Power disputes the contentions in the Sierra Club’s intent-to-sue notice. Officials with the utility tell the AP opacity can be caused by factors other than pollutants, citing water vapor as an example."
The 60-year oscillation revisited
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