The last 15 inter-glacial episodes 

The chart below presented he last 15 inter-glacial episode (labelled 1-15). Note that from 11,000 ya the chart has a significantly enlarged time scale. There seems little significant difference in the climate behaviour across the 15 inter-glacial episode, with the maximum temperatures for each little different from what is being experience today. This suggests that the current warming will probably follow a similar pattern. 

One significant difference is in the atmospheric CO2 behaviour in the present warming event (represented at the location marked "Present" below), where it extends to higher levels than for the other peaks (seen in earlier CO2 charts), reflecting the man-made (industrial), contribution, not experience in previous warming episodes. 

A useful diagram summarizing important climate & atmospheric data for the last 600 million years
Note that the time scale is not constant across the chart.

The diagram above updates the preceding temperature curve of Scotese et al. (1999), based on Frakes (1992), reproduced widely in this web site. The Scotese 2016 reference Web link is:


The earlier chart Scotese 1999, in my mind seems more realistic as it show sharper, more sudden short glacial events separated by longer, more even temperatures between. Sharper events seem more in keeping with causal cooling due to sharp, short planetary or geological triggers, which are much more easily explained. Long cooling events, many tens to hundreds of million years duration, seem a lot harder to account for with realistic planetary and geological mechanisms.  This will explain explain my continued use and preference for the 1999 Scotese chart.

 The 1999 chart cooling may be due to short planetary orbital or short geological events. The 2016 chart would suggest  much longer perhaps, reduced solar output, cooling events.  The geological & solar activity evidence seems more in favour  of the 1999 chart over the 2016.

In the "How confident are we that all this is correct" section in the above chart Scotese states - "I am not an expert in oxygen isotopes". So I leave this an open question as to which Scotese chart better or more accurately reflects the known science.  

The Last Million Years of Global Temperature Variations 

Temperatures recorded over the last million years, 10,000 years and 1,000 years are depicted in the chart below. The dashed line represents temperature conditions near the beginning of the 20th Century. Every portion of these graphs above this dashed line represents periods of time prior to the present that were warmer than at present and when atmospheric CO2 level were lower than at president.  These are periods within recent human history that we and human civilization all survived.

There is no atmospheric CO2 control over global temperature apparent in the geological or climate record. Atmospheric CO2 is minor (down to 400 ppm from several thousand ppm, dangerously low  for vegetation health and development and declining as it is inevitably  captured to form limestone - which is 44 wt % CO2 ). The 400 ppm in the atmosphere is all that existing and future life on Earth has to draw on to support and maintain itself.  CO2 is life affirming, and essential ingredient for all life and although decreasing in the long-run, fortunately harmless CO2 can be increased and replenished in the atmosphere relatively easily by burning fossil fuels. By continuing to burn fossil fuels we can extend life giving atmospheric CO2, at acceptable levels for all life, well into the future. 

The Greenland ICE Sheet Ice Core Studies 

The interesting features of these charts based on ice core studies over the last 10,000 years on the Greenland Ice Sheet, is the regularity of the the warming episodes. Every 1000 years each lasting 200-300 years, with around 2-3 degrees temperature shift up and down, with warming and cooling rates of around 1 degree/100 years (he same rate as presently estimated for the current warming. In the last 3000 years there has been an overall decline in temperatures. The CO2 data shows no correlation with temperature,  and CO2 increasing over time since 7000 year before present. 

This appears to show a 1000 year cyclical regularity in climate. Perhaps there exit a 24 hour daily temperature cycle, a 365 day yearly cycle, and a 1000 year cycle that has not previously been recognized. 

The lower diagram in this series reveals a bizarre relationship between ice core data from the north and south polar regions. The Greenland and Vostok (Antarctic) data are often the opposite of each other with one showing cooling while the other shows warming. What is happening here? Surely if CO2 is the driver, the CO2 levels should be the same world wide, and the temperature patterns should be the same in both hemispheres and at both poles. This would suggest a strong argument against the CO2-climate driver argument.