Every year some 500,000 km³ of water evaporates and falls back again, a closed loop powered by the Sun. The carbon cycle runs alongside it but leaves a readable trace: the Keeling curve carries an annual sawtooth, because Northern Hemisphere forests draw CO₂ down each summer and give it back each winter. As emissions grow the sawtooth survives while the whole line tilts upward, and deforestation cuts straight into the uptake side of the balance.
Every year some 500,000 km³ of water evaporates and falls back again, a closed loop powered by the Sun. The carbon cycle runs alongside it but leaves a readable trace: the Keeling curve carries an annual sawtooth, because Northern Hemisphere forests draw CO₂ down each summer and give it back each winter. As emissions grow the sawtooth survives while the whole line tilts upward, and deforestation cuts straight into the uptake side of the balance.
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