Superimposed on the background ‘hum’ of regular orbital cycles are several distinct spikes of strong climate change, too big or with too long a recovery time to be forced purely by orbital wobbles.
The earliest of these spikes is known as “ELPE” (Early Late Paleocene Event – 58.9 million years ago), which marks the end of the long term cooling trend in the Paleocene. It corresponds with a 4°C jump in ocean bottom water temperatures, swings in carbon isotope values, and ocean chemistry changes suggesting acidification. Intriguingly the ELPE coincides with a particularly violent phase of North Atlantic volcanic activity, resulting in the deposition of ash deposits like the Kettla Tuff in the Faroe-Shetland area, and contemporary volcanic ash deposits in western, and eastern Scotland, and igneous activity in Greenland and offshore Ireland.
Another sharp swing in ocean chemistry, carbon isotopes and abrupt ocean warming occurred at 57.7 Million years ago, known as the “Peak Paleocene Carbon Isotope Maximum” or “Peak PCIM.” Littler et al attribute the long term warming trend that began then and continued into the Eocene, to sustained carbon emissions resulting from North Atlantic Igneous Province activity.
The PETM (Paleocene-Eocene Thermal Maximum) is chief among the exceptional, non-cyclical, dramatic warming events, as these papers agree. Even though it began coincident with the 100,000 year orbital pacing, it was not in phase with the 405,000 year cycle that dominates the other Hyperthermals, suggesting an “extra push” was provided, probably by the spectacular eruptions from Canada to Norway that accompanied the opening of the North Atlantic at that time.
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