Orbits of Mars and Earth have an occasional resonance that drives the macro climate.

For years people wondered why earth's paleo-climate has warm spikes every hundred thousand years or so and other long range fluctuations, Mars may be part of the answer.  Earth and Mars orbits have some slight entanglement which every so often resonates, transferring some angular momentum from one planet to the other, making a small disturbance of the axis and orbit vis a vis the sun.    This is a bit preliminary but there's a signature in alternating layers of limestone and shale laid down some 87 million years ago in what's now Colorado and that's where it points.  Beautiful!!

Excerpted from HotAir.com where I first read about it.


More perspective from an article at iflscience.com:

"We know that orbital patterns known as Milankovitch cycles have been responsible for swings between glacial and interglacial conditions over the last few million years. These are a result of three things: Shifts between a more rounded and more elongated (or eccentric) orbit, the tilt of the Earth's axis, and the season in which Earth is closest to the Sun.  Meyers claims that during the Cretaceous, Martian gravity helped determine the first of these."