SCIENCE: Study gives first proof that the Earth has a natural thermostat.

The idea of a natural temperature thermostat was first proposed in 1981, but until now no-one has been able to provide data to show that the recovery from the hot and cold temperature fluctuations were associated with a specific mechanism.

Now a group of British scientists has shown that recovery from global cooling events is associated with changes in the rate of weathering of rocks, which is the main mechanism of removing CO2 from the atmosphere. In weathering, rocks are dissolved by rain and river water; the process removes CO2 from the atmosphere, which is then transported to the seas by rivers to be locked up in carbon-rich rocks such as limestone. The more weathering, the more CO2 is removed from the atmosphere.

The team had previously found evidence supporting the role of weathering in cooling the Earth in times of high temperature. This current work confirms that a slow-down of weathering takes place in cold periods, and so supports the concept of an “Earth thermostat”.

Fascinating.