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Find out how weathering of rocks stabilizes Earth's climate on geological timescales.

Earth has a built-in natural thermostat which stabilizes the climate on geological timescales. This thermostat is the slow weathering of rocks. It works because weathering or rocks (1) removes carbon dioxide from the atmosphere and (2) happens faster when it is warmer.

This animation shows how it works:

  • If Earth becomes warmer, rocks weather faster, removing carbon dioxide from the atmosphere faster than it is added by volcanoes. This causes the amount of carbon dioxide in the atmosphere to fall, weakening the greenhouse effect and making the Earth cooler.

  • If Earth becomes cooler, rocks to weather more slowly, which allows carbon dioxide from volcanoes to accumulate in the atmosphere. This causes the amount of carbon dioxide in the atmosphere to rise, strengthening the greenhouse effect and making the Earth warmer.

  • This negative feedback maintains a stable climate on geological timescales. Today, we add carbon dioxide to the atmosphere almost 100 times faster than it can be removed by weathering of rocks. In other words, Earth’s natural thermostat is far too slow to cope with our emissions

Finally, and only if you like chemistry, you might want to see an example of a reaction whereby rocks dissolve. The following reaction is written for the rock-forming mineral, feldspar (KAlSi3O8):

2 KAlSi3O8(s) + 3 H2O + 2 CO2(g) → Al2Si2O5(OH)4(s) + 4 SiO2(aq) + 2 K+ + 2 HCO3

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