[gondramB]

>>I would say we can reasonably figure on toggling between deep glacial conditions and moderate temperatures for a few more million years if that is your delta.<<

I was unclear, I meant the current first derivative with respect to time. It would not have to stay at the current rate for the last 30 years very long to break what have been some historic natural barriers.

[ancient_geezer]

I was unclear, I meant the current first derivative with respect to time. It would not have to stay at the current rate for the last 30 years very long to break what have been some historic natural barriers.

The 8ky trend is currently downward. 30yrs against 8kys of tend is a pittance and one not to be ignored especially in light of the reality and inevitability of orbital mechanics, both in the shorter geological periods of 100kys of planetary mechnics, and those of intergalactic operative on the scale of 100 million years displayed in reply #37.

[ancient_geezer]

Another interesting graphic from Muller's works on the history of climate displaying a much longer time scale, albeit reversed from those above with present temperature to the left instead of the right in the charts above.

From Ice Ages & Astronomical Causes
Brief Introduction to the History of Climate
by Richard A. Muller

 

In Figure 1-6, the 10 kyr years of agriculture and civilization appear as a sudden rise in temperature barely visible squeezed against the left hand axis of the plot. The temperature of 1950 is indicated by the horizontal line. As is evident from the data, civilization was created in an unusual time.

There are several important features to notice in these data, all of which will be discussed further in the remainder of the book. For the last million years or so (the left most third of the plot) the oscillations have had a cycle of about 100 kyr (thousand years). That is, the enduring period of ice is broken, roughly every 100 kyr, by a brief interglacial. During this time, the terminations of the ice ages appear to be particularly abrupt, as you can see from the sudden jumps that took place near 0, 120, 320, 450, and 650 thousand years ago. This has led scientists to characterize the data as shaped like a "sawtooth," although the pattern is not perfectly regular.

Figure 1-6 Climate of the last 3 million years

 

As can be clearly noted, we have been on a much longer trend downward trend overall across the last 3 million years with the 100kyr cycle deepening and becoming more pronounce on the downside. Entertaining the strong concept that continuation in the established 100kyr periodicity is hardly at an end with deep glacial eras yet to come.