Earth’s lungs are choking on plastic and smoke – scientists hope to unblock them

A graph I saw in high school appeared to show the Earth breathing.

It was a graph that plotted carbon dioxide in the atmosphere over the course of the 20th century and into the 21st. CO₂ had risen steadily, and then more rapidly, but it hadn’t gone up in a straight line. Each year it had fallen sharply before rising to a new peak, increasing over time in an upwards zig-zag.

What explained this annual, temporary fall in CO₂, the gas that is overwhelmingly responsible for climate change? The answer was photosynthesis, my physics teacher explained – the miracle by which plants…

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