SIGNIFICANT CLIMATE CHARTS OVERVIEW, ICE CORE DATA, & MILANKOVITCH CYCLES
Frakes (1979) modified after Condi (2011). Mean global temperature & precipitation throughout geological time. & a brief explanation of the Steady-State Climate Model.
Temperature after Scotese (2002), & CO2 after Pagani et.al, (2005), with contributions by others.
Main features are a fairly constant global temperature outside glacial events until the Tertiary, and a dramatic almost liner decline in CO2 over time & a massive depletion in CO2 in the Carboniferous-Permian following the massive invasion of plants on land. A dated but widely used chart, much criticized by climate alarmists (somewhat unfairly). A comparison of this with later charts displayed below, reveals an overall remarkable similarity.
Allaby (2007). A chart in two parts with the second part featuring a significant enlargement of the Pleistocene-Holocene.
The Pleistocene-Holocene significantly enlarged with additional labelling.
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.
Modified after Allaby (2007), with additional labelling.
A side-by-side comparison of five significant climate charts. The time scales vary within and between these charts and the charts themselves cover a publication range of some 40 years, during which time, the quality and quantity of climate data have improved considerably. Taking this into account, the charts reveal a remarkable similarity, especially over the last 65 million years, the period leading into and most relevant to the current climate debate.
A useful diagram based on Scotese & Pagani's charts above, but modified by more recent work on the Holocene, but including lots of other additional information.
The diagram below Scotese (2016), updates the preceding temperature curve of Scotese et al. (2002),.
The Scotese 2016 reference Web link is:
https://researchgate.net/publication/309324713_A_NEW_GLOBAL_TEMPERATURE_CURVE_FOR_THE_PHANEROZOIC…
The earlier chart Scotese 2002, in my mind seems more realistic as it shows 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 help explain the continued use and preference for the 2002 Scotese chart.
In the "How confident are we that all this is correct" section in the above Scotese 2016
chart states - "I am not an expert in oxygen isotopes". The 2002 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 2002 chart over the 2016. So I leave this as an open question as to which Scotese chart better or more accurately reflects the known science.
A more recent temperature chart showing more detail, particularly from the Palaeocene to the present is presented in the section below. Temperatures recorded particularly over the last 100 million years, and over the last 5 million and 1 million years are depicted in considerably more detail.
The Last Million Years of Global Temperature Variations
Temperatures recorded over the last 500 million years, and in more detail over shorter periods in more detail in the charts below.
Greenland & Antarctic Ice Core Data
Bubbles of air become trapped as ice forms and CO2 is measured directly in trapped air bubbles in ice cores. Temperature however is inferred from the oxygen isotope ratio of oxygen -16 to oxygen 18 in water molecules released by melting the ice cores.
The interesting features of the charts based on ice core studies over the last 10,000 years on the Greenland ice sheet below, 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 illustrated with the red arrow (the 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.
Continuous ice core data can only be recovered from a number of very young, thick ice-sheet locations preserved at high latitudes. They allow very close sampling and a continuous detailed climate record not achievable by other methods, but only extends back some 800,000 years and immediately relatable to cold, high latitude environments. Some global climate extrapolation is possible.
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. There seems to be a countercyclical relationship between the poles and hemispheres.
Ice core evidence that the most recent man-made CO2 increase (due to fossil fuel use in the last 200 years), has not been accompanied by any equivalent temperature increase.
In the chart below over the last 350,000 years both temperature and atmospheric CO2 recorded from Vostok ice core data are presented. A strongly developed, very regular, asymmetric, zig-zag sawtooth pattern is revealed, and a close correlation is noted with temperature narrowly preceding CO2. What is unusual is that there has been no temperature increase to match the 200 to 415 ppm increase in CO2 recorded in 2019. The magnitude of missing temperature should be some 8 degrees F, measured and scaled against other peaks in the chart. This because this is a known instance where CO2 increased first, before temperature, and provides proof that CO2 is not a temperature driver? Or is there a temperature delay, not yet registered, where temperature follows CO2. In this latter case this temperature delay is certainly not seen elsewhere in this chart?
Milankovitch Cycles
The repeating 100,000 year, asymmetric zig-zag pattern temperature and CO2 pattern displayed above, and the other smaller repeating peak and troughs cycles, seem to conform to cyclical patterns observed for the Earths orbit around the sun (eccentricity), and systematic Earth axial tilt, and wobble behaviour (called precession), recognised as Milankovitch Cycles. The geometry, character and periodicity of these is displayed below.
What is causing these climate cycles?
The temperature relationship to the Milankovitch cycles (particularly the100,000 year orbital eccentricity cycle), is clear. Each eccentric cycle begins with short rapid warming during the short ellipse phase with the Earth closer to the sun, followed by the much slower cooling phase as the ellipse extend to it's maximum. There is some debate as to whether the shorter warmer orbit is sufficient to account for the heating, or if the associated increase in greenhouse CO2 provides additional slightly lagging feed back. Orbital cycles certainly control the temperature cycles but cannot by themselves account for regular CO2 cycles. The smaller duration Milankovitch cycles contribute to the lesser peaks.
The regularity of the 1000 year cyclical peaks the regular smaller peaks between, registered and illustrated in the GISP2 Greenland Holocene ice cores featured earlier, are also likely to have as yet unrecognised celestial controls at these much smaller time scales.