Permanent El Niño-Like Conditions During the Pliocene Warm Period

  title={Permanent El Niño-Like Conditions During the Pliocene Warm Period},
  author={Michael Wara and Ana Christina Ravelo and Margaret Lois Delaney},
  pages={758 - 761}
During the warm early Pliocene (∼4.5 to 3.0 million years ago), the most recent interval with a climate warmer than today, the eastern Pacific thermocline was deep and the average west-to-east sea surface temperature difference across the equatorial Pacific was only 1.5 ± 0.9°C, much like it is during a modern El Niño event. Thus, the modern strong sea surface temperature gradient across the equatorial Pacific is not a stable and permanent feature. Sustained El Niño-like conditions, including… 
Permanent El Niño during the Pliocene warm period not supported by coral evidence
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Evidence for El Niño–like conditions during the Pliocene
The modern tropical Pacific Ocean is characterized by strong east-west asymmetry in sea surface temperature and subsurface thermocline depth coupled to easterly trade winds and zonal atmospheric, or
Not So Permanent El Niño
  • D. Lea
  • Environmental Science, Geography
  • 2014
The equatorial Pacific was warmer during the Pliocene and late Miocene than it is today and the temperature difference between the eastern and western tropical Pacific that is a fundamental characteristic of today's ocean was present during these warmer time intervals.
The Pliocene Paradox (Mechanisms for a Permanent El Niño)
A future melting of glaciers, changes in the hydrological cycle, and a deepening of the thermocline could restore the warm conditions of the early Pliocene.
Tropical cyclones and permanent El Niño in the early Pliocene epoch
A positive feedback between hurricanes and the upper-ocean circulation in the tropical Pacific Ocean that may have been essential for maintaining warm, El Niño-like conditions during the early Pliocene is described.
Pliocene warmth and gradients
The Pliocene epoch (5.3–2.6 Ma) generates continued debate as an example of a warm climate with external forcing similar to the present day. O'Brien et al. presented new multi-proxy sea surface
Patterns and mechanisms of early Pliocene warmth
The available geochemical proxy records of sea surface temperature are synthesized and it is shown that, compared with that of today, the early Pliocene climate had substantially lower meridional and zonal temperature gradients but similar maximum ocean temperatures.
Simulating Pliocene warmth and a permanent El Niño‐like state: The role of cloud albedo
Available evidence suggests that during the early Pliocene (4–5 Ma) the mean east-west sea surface temperature (SST) gradient in the equatorial Pacific Ocean was significantly smaller than today,
Dampened El Niño in the Early Pliocene Warm Period
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Greatly Expanded Tropical Warm Pool and Weakened Hadley Circulation in the Early Pliocene
This reconstruction shows that the meridional temperature gradient between the equator and subtropics was greatly reduced, implying a vast poleward expansion of the ocean tropical warm pool, which had enormous impacts on the Pliocene climate.


Cool La Niña During the Warmth of the Pliocene?
The Pliocene paleothermometer supports the idea of a dynamic “ocean thermostat” in which heating of the tropical Pacific leads to a cooling of the east equatorial Pacific and a La Niña–like state, analogous to observations of a transient increasing east-west sea surface temperature gradient in the 20th-century tropical Pacific.
Upwelling intensification as part of the Pliocene-Pleistocene climate transition.
A deep-sea sediment core underlying the Benguela upwelling system off southwest Africa provides a continuous time series of sea surface temperature (SST) for the past 4.5 million years. Our results
Role of tropics in changing the response to Milankovich forcing some three million years ago
appeared in regions that today have intense oceanic upwelling: the eastern equatorial Pacific and the coastal zones of southwestern Africa and California. There was furthermore a significant change
We evaluated the response of eastern equatorial Pacific upper water column hydrography to the Panama seaway closure and the initiation of large-scale northern hemisphere glaciation, The δ18O gradient
Regional climate shifts caused by gradual global cooling in the Pliocene epoch
Climate records from high latitudes, subtropical regions and the tropics are compared, indicating that the onset of large glacial/interglacial cycles did not coincide with a specific climate reorganization event at lower latitudes and suggesting that mean low-latitude climate conditions can significantly influence global climate feedbacks.
Evolution of El Niño–Southern Oscillation and global atmospheric surface temperatures
[1] The origins of the delayed increases in global surface temperature accompanying El Nino events and the implications for the role of diabatic processes in El Nino–Southern Oscillation (ENSO) are
Slowdown of the meridional overturning circulation in the upper Pacific Ocean
It is shown that the wind-driven meridional overturning circulation between the tropical and subtropical oceans has been slowing down since the 1970s, causing a decrease in upwelling in an equatorial strip between 9° N and 9°S, which is associated with a rise in equatorial sea surface temperatures.
Is El Nino changing?
Apparent changes in the properties of El Nino could reflect the importance of random disturbances, but they could also be a consequence of decadal variations of the background state and the possibility that global warming is affecting those variations cannot be excluded.
Pliocene development of the east‐west hydrographic gradient in the equatorial Pacific
Foraminifer count and multispecies isotopic data from Ocean Drilling Program (ODP) Sites 806 (0°N, 165°E) and 847 (0°N, 95°W) are presented for the last 6.4 m.y. Faunal evidence shows a decline of