There are two external solar bodies that have a large effect on our climate, the Sun and the moon. In all the information that I have read on this web site, there is no mention of the moon. Specifically, the effect of gravitational force of the pull of the moon as it moves away from the earth causing a braking of the earths rotation. If this calculation is not part of the mathematics that is use by climateprediction.net, then it needs to be.

Most would say that it does move that much, but when a mass that large moves any distance it has effect.

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Though the moon might have no noticeable effect on climate over human timescales, its influence on the effects of climate change will in some circumstances be significant. London, for example, is protected from flooding by the Thames Barrier. The worst-case scenario for London is high outward river flows, a high tide in the Thames Estuary with a North Sea storm surge behind it. If the barrier were overtopped then the flooding in London would be catastrophic. Climate change contributes to all three of those by raising sea levels and increasing the intensity of storms both on land and at sea. It might well be the case that in practice some fluke of the regional climate makes one or other factor anti-correlated - perhaps a storm surge coming down the North Sea cannot happen at the same time as the saturation of South-East England by an Atlantic storm. In any event the moon itself would not be modelled directly but its tidal effects would. Without any specific knowledge I would assume that the trend of the moon's recession is a very slow decline in the height of tides.

If my math is correct then the moon is moving away about 1.5 inches a year, which is 3.81 cm. I am not talking about the tidal effects of the moon but the actual slowing of the planet's rotation by the braking effect that the moon has on the planet earth.


Planet's rotation each year is slowed just a little bit, that means there is more time in the sunlight or in darkness. The moon's gravitational force as it moves away will be more of threat to climate than anything else. But people seem not to worry because they will not be here.

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The trend in the Earth's rotation appears to be about 2.3 ms per century, or 2.3 s per 100,000 years. Over that timescale the Earth in its current phase would go through an ice age cycle. Again I doubt the slowdown is significant on any timescale that would be worth modelling on CPDN.

So it looks like we'll have an enormously greater effect on the Earth's climate than this aspect of solar system evolution.