Christian Science Monitor: When Earth Day observances first began in 1970, Cleveland had recently doused a pollutant-fueled fire on a section of the Cuyahoga River. Cities were often shrouded in thick blankets of smog. And large portions of Lake Erie were so fouled by industrial, farm, and sewage runoff that sections of the 241-mile-long lake were pronounced dead.
As an environmental issue, global warming was far down the list of concerns.
At the time, a small number of climate scientists noted a general cooling trend...