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Earth and Space Sciences · Glossary

What is Hyperthermal event; Palaeocene–Eocene Thermal Maximum?

Also known as: hyperthermal event · Palaeocene--Eocene Thermal Maximum

Definition 26.7 University Earth and Space Sciences — Year 2 · Chapter 26 — Climate over Geological Time

A hyperthermal event is a geologically brief global warming, a few thousand to a few hundred thousand years long, caused by a rapid release of carbon to the ocean and atmosphere and recorded by a fall of the δ13\delta^{13}C of marine and terrestrial carbon, a dissolution of sea-floor carbonate and a fall of δ18\delta^{18}O. The Palaeocene–Eocene Thermal Maximum (PETM), 55.9 to 55.7 Ma55.7\,\mathrm{Ma}, is the largest of the Cenozoic; its onset marks the base of the Eocene.

The PETM in the CENOGRID splice, on its grid of 5\, kyr. Top: benthic 13C falls by about 3.7\, ‰ from its mean before the event; bottom: 18O, axis reversed, falls as the deep sea warms. The straight stretch from 55.93 to 55.865\, Ma is not a slow onset: no shell was measured there, and the splice joins the last point before the event to the first one inside it. The recovery, from right to left, takes a hundred thousand years.
The PETM in the CENOGRID splice, on its grid of 5 kyr5\,\mathrm{kyr}. Top: benthic δ13\delta^{13}C falls by about 3.7 ‰3.7\,\text{‰} from its mean before the event; bottom: δ18\delta^{18}O, axis reversed, falls as the deep sea warms. The straight stretch from 55.93 to 55.865 Ma55.865\,\mathrm{Ma} is not a slow onset: no shell was measured there, and the splice joins the last point before the event to the first one inside it. The recovery, from right to left, takes a hundred thousand years.
The PETM as a sequence (schematic): a release of carbon over 3 to 20\, kyr, a warm interval, and a recovery of the ocean’s carbonate over about 100\, kyr; the whole event spans some 200\, kyr. The length of the warm body is drawn to fill the interval, not measured.
The PETM as a sequence (schematic): a release of carbon over 3 to 20 kyr20\,\mathrm{kyr}, a warm interval, and a recovery of the ocean’s carbonate over about 100 kyr100\,\mathrm{kyr}; the whole event spans some 200 kyr200\,\mathrm{kyr}. The length of the warm body is drawn to fill the interval, not measured.
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