A 12-Million-Year Temperature History of the Tropical Pacific Ocean

Science ◽  
2014 ◽  
Vol 344 (6179) ◽  
pp. 84-87 ◽  
Author(s):  
Yi Ge Zhang ◽  
Mark Pagani ◽  
Zhonghui Liu
Keyword(s):  
El Niño ◽  
El Nino ◽  
Warm Pool ◽  
Sea Surface ◽  
Temperature History ◽  
Seawater Chemistry ◽  
The Pacific ◽  
Pacific Warm Pool ◽  
History Of ◽  
The Tropical Pacific

The appearance of permanent El Niño–like conditions prior to 3 million years ago is founded on sea-surface temperature (SST) reconstructions that show invariant Pacific warm pool temperatures and negligible equatorial zonal temperature gradients. However, only a few SST records are available, and these are potentially compromised by changes in seawater chemistry, diagenesis, and calibration limitations. For this study, we establish new biomarker-SST records and show that the Pacific warm pool was ~4°C warmer 12 million years ago. Both the warm pool and cold tongue slowly cooled toward modern conditions while maintaining a zonal temperature gradient of ~3°C in the late Miocene, which increased during the Plio-Pleistocene. Our results contrast with previous temperature reconstructions that support the supposition of a permanent El Niño–like state.

Response to Comment on “A 12-million-year temperature history of the tropical Pacific Ocean”

Science ◽  
2014 ◽  
Vol 346 (6216) ◽  
pp. 1467.2-1467 ◽  
Author(s):  
Yi Ge Zhang ◽  
Mark Pagani ◽  
Zhonghui Liu
Keyword(s):  
Warm Pool ◽  
Temperature Data ◽  
Temperature Gradients ◽  
Sea Surface ◽  
Temperature History ◽  
Tropical Pacific Ocean ◽  
The Past ◽  
Pacific Warm Pool ◽  
History Of ◽  
The Tropical Pacific

Contrary to our conclusions, Ravelo et al. argue that our TEX86-based sea surface temperature (SST) records do not conflict with the supposition of “permanent El Niño–like” conditions during the early Pliocene. We show that the way Ravelo et al. treat the existing temperature data perpetuates an inaccurate impression of cooler Pacific warm-pool SSTs and low equatorial temperature gradients in the past.

scholarly journals The Influence of the 1998 El Niño upon Cloud-Radiative Forcing over the Pacific Warm Pool

2001 ◽  
Vol 14 (9) ◽  
pp. 2129-2137 ◽  
Author(s):  
Robert D. Cess ◽  
Minghua Zhang ◽  
Bruce A. Wielicki ◽  
David F. Young ◽  
Xue-Long Zhou ◽  
...  
Keyword(s):  
El Niño ◽  
Radiative Forcing ◽  
El Nino ◽  
Warm Pool ◽  
Cloud Radiative Forcing ◽  
The Pacific ◽  
Pacific Warm Pool

Comment on “A 12-million-year temperature history of the tropical Pacific Ocean”

Science ◽  
2014 ◽  
Vol 346 (6216) ◽  
pp. 1467.1-1467 ◽  
Author(s):  
Ana Christina Ravelo ◽  
Kira Trillium Lawrence ◽  
Alexey Fedorov ◽  
Heather Louise Ford
Keyword(s):  
Pacific Ocean ◽  
El Nino ◽  
Warm Pool ◽  
Tropical Pacific ◽  
Temperature History ◽  
Published Data ◽  
Tropical Pacific Ocean ◽  
History Of ◽  
The Tropical Pacific ◽  
New View

Zhang et al. (Reports, 4 April 2014, p. 84) interpret TEX86 and U37K' paleotemperature data as providing a fundamentally new view of tropical Pacific climate during the warm Pliocene period. We argue that, within error, their Pliocene data actually support previously published data indicating average western warm-pool temperature similar to today and a reduced zonal gradient, referred to as a permanent El Niño–like state.

A Study of the Impact of Off-Equatorial Warm Pool SST Anomalies on ENSO Cycles

2005 ◽  
Vol 18 (2) ◽  
pp. 274-286 ◽  
Author(s):  
Amy Solomon ◽  
Fei-Fei Jin
Keyword(s):  
El Niño ◽  
El Nino ◽  
Coupled Model ◽  
Warm Pool ◽  
Western Pacific ◽  
Sea Surface ◽  
Pacific Warm Pool ◽  
The Impact ◽  
The Western Pacific ◽  
Sst Anomalies

Abstract Concurrent with most large El Niño events, cold sea surface temperature (SST) anomalies are observed over the western Pacific warm pool region (WPWP). Observational evidence that SST anomalies that form in the off-equatorial western Pacific during El Niño–Southern Oscillation (ENSO) cycles are forced by subsurface ocean processes equatorward of 12°N and air–sea fluxes poleward of 12°N is presented. It is demonstrated that diurnal mixing in the ocean equatorward of 12°N plays a significant role in bringing subsurface temperature anomalies to the sea surface during an El Niño event. The role of SST anomalies equatorward of 12°N in ENSO cycles is tested in the Zebiak–Cane coupled model, modified to allow for the impact of subsurface temperatures on SSTs. This coupled model successfully simulates cold SST anomalies in the off-equatorial northwestern Pacific that are observed to occur during the warm phase of ENSO and the atmospheric response to these anomalies, which is composed of both westerlies in the central Pacific and easterlies in the far western equatorial Pacific. It is found that there is little net change in the zonal mean wind stress at the equator, suggesting that the westerlies cancel the impact of the easterlies on the basin-scale tilt of the equatorial zonal mean thermocline depth. The anomalous westerly winds in the central equatorial Pacific are found to increase the amplitude of an El Niño event directly by increasing anomalous warm zonal advection and reducing upwelling. Moreover, the off-equatorial anticyclonic wind stress associated with the cold SST anomalies during the warm phase of ENSO tends to reduce the discharge of the equatorial heat content. Thus, the coupled processes over the western Pacific warm pool can serve as a positive feedback to amplify ENSO cycles.

scholarly journals A Simple Analytical Model for Understanding the Formation of Sea Surface Temperature Patterns under Global Warming*

2014 ◽  
Vol 27 (22) ◽  
pp. 8413-8421 ◽  
Author(s):  
Lei Zhang ◽  
Tim Li
Keyword(s):  
Global Warming ◽  
Indian Ocean ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
El Niño ◽  
El Nino ◽  
Tropical Pacific ◽  
Sea Surface ◽  
The Tropics ◽  
The Tropical Pacific

Abstract How sea surface temperature (SST) changes under global warming is critical for future climate projection because SST change affects atmospheric circulation and rainfall. Robust features derived from 17 models of phase 5 of the Coupled Model Intercomparison Project (CMIP5) include a much greater warming in high latitudes than in the tropics, an El Niño–like warming over the tropical Pacific and Atlantic, and a dipole pattern in the Indian Ocean. However, the physical mechanism responsible for formation of such warming patterns remains open. A simple theoretical model is constructed to reveal the cause of the future warming patterns. The result shows that a much greater polar, rather than tropical, warming depends primarily on present-day mean SST and surface latent heat flux fields, and atmospheric longwave radiation feedback associated with cloud change further enhances this warming contrast. In the tropics, an El Niño–like warming over the Pacific and Atlantic arises from a similar process, while cloud feedback resulting from different cloud regimes between east and west ocean basins also plays a role. A dipole warming over the equatorial Indian Ocean is a response to weakened Walker circulation in the tropical Pacific.

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