Neo, you are right that it's the large long cycles which provide the impetus in climate, just as in volcanoes it's the subduction process over thousands of years which fills the magma chambers to over flowing. But it's the transient pressure relief which precipitates the eruption and similarly for the glaciation.
When the Moon and Sun pull in conjunction, the cap on the pressure cooker is removed and the liquids turn to gas and that pushes overburden off which causes more pressure reduction and more liquid converting to gas and so on down the column. Suddenly, the nice, quiet, beautiful Lake Taupo turns to a 10 km high column of frothing pumice, burning hydrocarbons, CO2, H2O and stuff.
A glaciation process is less dramatic, but equally detrimental to property values in the area affected.
Humans don't live their individual lives on the scale of millions of years. We last less than a century. So what matters is WHEN the glaciation will arrive. If it's 1000 years from now, we can ignore it and build cities right in the way of a glacier's certain path. If it's 100 years from now we can build a city and still get our money's worth over that 100 years. If it's 10 years, we might build a low cost house but not too many of them. If it's a month, we'd use a tent.
We know how long the cycles are in ice ages because of how long glaciations last and how long the interglacials last. 10,000 years is a good cycle for an interglacial. Which happens to be how long it has been since the last glaciation.
If the latest sun spot cycle actually gets going, we can expect that the ice age will not return until the next minimum. That's quite a few years from now. If the sun spot cycle doesn't get going, we could plunge into glaciation during this northern winter.
If we get a Taupo eruption for Xmas, the chances of glaciation go up a lot.
Mqurice |
