Maybe you’ve heard the news: Last month, for the first time in 800,000 years, the world’s carbon dioxide level passed 400 parts per million (ppm), and stayed that way all of April. This was the milestone that we’ve been anticipating for many years.
It was just 330 ppm when the Beatles were big. Earlier, when many of us were in kindergarten, CO2 was 315 ppm. It had taken a long time to get there. Before the Industrial Revolution, and going back for almost a million years, the level was 280 ppm.
It will fall back below . . .
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