As can be seen in the above graphic, isotopic data derived from ice-cores, deep-sea sediment sediments and other proxies shows dramatic and a characteristic “saw-tooth” signature over the Pleistocene (1.2 million years).
For a compilation of the same oxygen isotope and other data over the last 2.7 million years (which shows the same repetitive saw tooth change in climate/temperature proxies) see the image below:
This data shows very clearly that longer periods of slow cooling are followed (or preceded!) by dramatic periods of warming. The current warming period commenced well before recent industrialisation and consistent with the trend and the satellite temperature data would now seem to be at or close to its peak. Is it any wonder that humanity has prospered during this warming period.
This data suggests that we should expect a slow cooling in the near future and the implications of that for humanity will be serious with declines in crop production and likely population unless we have averted the catastrophic impacts through CO2 emissions.
Fossil fuel usage saved the earth from the ravage of a growing population in the past and it is possible that it is now saving humanity from the next ice-age that is if the miniscule contribution of humanity to planet wide CO2 production is having any meaningful impact.
Original Research:
- Braithwaite, Colin, 2016, Coral-reef records of Quaternary changes in climate and sea-level, Earth-Science Reviews 156 (2016) 137–154
- Elderfield, H., Ferretti, P., Greaves, M.M., Crowhurst, S., McCave, I.N., Hodell, D.A., Piotrowski, A.M., 2012. Evolution of ocean temperature and ice volume through the mid-Pleistocene climate transition. Science 337, 704–709.
- Gibbard, P., Cohen, K.M., 2008. Global chronostratigraphical correlation table for the last 2.7 million years. Episodes 31 (2), 243–247.