The variations include the eccentricity of the Earth's orbit around the Sun, the degree to which its axis is inclined, and the slow rotation of its axis.
These all take place on timescales of tens of thousands of years.
The precise way in which they change the climate of the Earth from warm interglacial to cold Ice Age and back every 100,000 years or so is not known.
On their own, they are not enough to cause the global temperature difference of about 10C between Ice Age and interglacial. The initial small changes are amplified by various factors including the release of carbon dioxide into the atmosphere as warming begins, and absorption of the gas by the oceans as the ice re-forms."
Source bbc.co.uk: Carbon emissions 'will defer Ice Age'
Shivers... brrr... This means that all this Kyoto Protocol trading scam would have brought us closer to the next ice age. Good riddance.
"The broad conclusions of the team were endorsed by Lawrence Mysak, emeritus professor of atmospheric and oceanic sciences at McGill University in Montreal, Canada, who has also investigated the transitions between Ice Ages and warm interglacials.
"The key thing is they're looking about 800,000 years back, and that's twice the 400,000-year cycle, so they're looking at the right period in terms of what could happen in the absence of anthropogenic forcing," he told BBC News.
He suggested that the value of 240ppm CO2 needed to trigger the next glaciation might however be too low - other studies suggested the value could be 20 or even 30ppm higher."
Translated to politically induced language, more amazing science (keep in mind: so far as you blindly believe in "science" that's not like religion, it's different, ya know) is telling us the following: we have to burn all the gas and all the crude oil at hand (as much as we can, as fast as we can) in order to keep the CO2 levels high, and possibly bring them higher, so that we can force back, in our anthropogenic well-known style, the next Ice Age (no, not the movie Ice Age 4; we love the movie!; right, Sid?).
Drill, baby, drill! And burn, baby, burn! This should be the slogan for environmentalists and planet lovers, tree huggers, of the morrow. They'll have good reason to demand from their old Nemesis (Big Oil) to sink the prices for crude and natural gas so that the people can burn more of it, and faster, to keep CO2 high, for the sake of mother nature...
Cancer by benzene intoxication would cause more death than the sinking Maldives, the fewer polar bears or Lex Luthor's new Nevada shoreline.
I, for one, am skeptical about the weather forecast announcing yet another cold spell for the next weekend. I just ponder what if some unexpected hot air will counter again with a mild fuss. On the contrary, I'm almost certain about the expected temperatures for tomorrow. Although nothing is carved in stone, short range predictions give us a practical sense in life, while long range (or too long, or beyond-the-eon long) forecasts are just excellent theories. Not something to rely on with your plans or money. Unless you're a statist swindler or a political gambler.