mistermack wrote:What's crystal clear from the ice core data from the last 400,000 years is
1) We are due an ice age
In about 30,000 years, is the current mainstream view. And in fact, that's not clear from ice core data at all; it's clear from the exact nature and timing of the Milankovitch cycles.
mistermack wrote:2) Warming Feeback mechanisms have ALWAYS stopped at the current levels ( if they existed )
No. The Paleocene-Eocene Thermal Maximum peaked at about 12°C above where it is today.
But even that's nowhere near as hot as it's ever been on Earth. At the end of the Cambrian Explosion, when millions of species suddenly appear in the geological record, the CO2 content of the atmosphere was well above 4000 PPM, about ten times what it is today; some estimates put it as high as 7000 PPM. This implies a climate about 20°C warmer than today, with almost no polar caps. It took through the Ordovician, Silurian, and Devonian for the plants with stems to evolve in the oceans, colonize the land, evolve into enormous forests, and capture all that CO2, bringing the CO2 down nearly to 200 PPM. This, combined with the Milankovitch cycles, caused the second longest ice age in the history of the planet, the Karoo Ice Age, which lasted nearly a hundred million years, until the beginning of the Permian. (The longest is called the Cryogenian, and featured the Earth being frozen into a climate "strange attractor" state called "Snowball Earth," which is just what it sounds like: the Earth is covered with ice, reflecting most of the heat back to space, and the Milankovitch cycles are not strong enough except at their highest insolation state to break the hold of the attractor. That took a long, long time to come around.)
mistermack wrote:3) The 800 year lag is consistent over the whole period
What "whole period?" 400,000 years? That's jack-shit. I just talked about the PETM which happened sixty million years ago, a period over a hundred times longer. The Vostok ice core goes back 11 or 12 million, twenty-five times longer. And those are in the recent past; the beginning of the Cambrian is five hundred million years ago. Stop cherry-picking.
As far as the 800-year lag, it is irrelevant whether it was consistent or not; you'd know that if you'd read the Real Climate article I linked. Nobody's denying the lag; what you don't get is that not all the warming's due to CO2, the CO2
amplifies the Milankovitch cycle-caused warming.
mistermack wrote:4) Most of the current warm temps are due to warming that happened 10 to 15,000 years ago.
Todays warming is small in comparison.
This is word salad.
11,000 years ago, the Milankovitch cycles caused the Earth to start getting warmer. About 800 years after that, enough heat had accumulated to allow animals to start growing in the sea enough to raise the CO2 level from around 220 to around 290 PPM. At that point, global warming took over and warmed us the rest of the way to where we were up until the eighteenth century, more or less. At that point, we started burning coal and oil enough to raise the CO2 levels gradually to where they are today, approaching 400 PPM.
As far as today's warming being "small in comparison," I don't even know what that means. Let's stick with quantifications that include numbers, OK?
