Vast climate changes are not new to Earth. 450 million years ago most of the present-day United States was underwater. 20,000 years ago New England was buried beneath a mile-thick glacier. Although climate change triggered mass extinctions, life on Earth continued.
But why? Climate change turned Venus into a barren hellscape, but Earth never became hot or cold enough to wipe out all life.
This question led to speculation on the existence of a planetary thermostat that keeps climate change in check. A new study published in the journal Geochemical Perspectives Letters provides the first-ever evidence of its existence.
The climate must be relatively constrained. It can’t change too much, otherwise life would go extinct.”
“There must be some mechanism that prevents the climate from going completely crazy,” according to Philip Pogge von Strandmann, a geochemist at University College London and lead author of the study.
“Weathering thermostat” is the name assigned to that mechanism. Carbon dioxide (CO2) traps heat, keeping the Earth warm. A drop in CO2 brings about lower temperatures and a potential ice age. A drastic increase in CO2 brings melting of the polar ice caps and flooding.
However, Earth regulates CO2 through weathering which sustained some life on the planet during previous extreme hot or cold periods. Atmospheric CO2 dissolves in rainwater and combines with rocks to form bicarbonate runoff.
If you a dissolve a rock in water — rain water, river water — that process takes CO2 out of the atmosphere and puts it in the water as bicarbonate.”
“That goes from the rivers into the ocean,” said Pogge von Strandmann. Once in the ocean, the bicarbonate combines with calcium and forms limestone. “That locks in the carbon dioxide.”
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