A headline on a Washington Post news story in the June 8 Press Herald (Page A2) states “Atmospheric carbon dioxide reaches highest levels in 63 years.”

This statement is open to misinterpretation: It suggests that carbon dioxide, or CO2, levels prior to 63 years ago might have been higher than now. In fact, the opposite is the case. Fossil fuels combustion has steadily raised atmospheric CO2 levels to the highest levels in 400,000 years.

The only thing special about 63 years ago is that it was the starting date of one particular CO2 dataset, and not any watershed moment in Earth’s CO2 history.

Bill Danielson
Chebeague Island

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