Glacial sea surface temperature reconstruction in the west pacific warm pool

1998 ◽  
Vol 43 (S1) ◽  
pp. 89-89
Author(s):  
G. R. Min ◽  
F. W. Taylor ◽  
J. Recy ◽  
G. S. Burr ◽  
R. L. Edwards ◽  
...  
2020 ◽  
Author(s):  
Niklas Meinicke ◽  
Maria Reimi ◽  
Christina Ravelo ◽  
Nele Meckler

<p>The Western Pacific Warm Pool (WPWP) as a major source of heat and water vapor has a crucial influence on climate dynamics both in the tropics and globally. Yet, there is conflicting proxy evidence regarding the evolution of WPWP temperatures since the Miocene. On the one hand TEX<sub>86</sub> data suggest a gradual cooling by ~2℃ (O’Brian et al., 2014, Zhang et al., 2014) from the Pliocene to today, while faunal (planktonic foraminifera) sea surface temperature estimates (Dowsett, 2007) and Mg/Ca data measured in planktonic foraminifera (Wara et al., 2005) on the other hand indicate the absence of any long-term temperature trends. It has been suggested that Mg/Ca temperatures could on these time scales be biased by long-term changes of the Mg/Ca ratio of seawater (Evans et al., 2016). To test the influence of the proposed seawater changes on Mg/Ca we combined data from two independent temperature proxies, Mg/Ca and clumped isotopes, measured on two species of planktonic foraminifera from IODP Site U1488 in the central WPWP. Our study finds good agreement between both proxies thereby verifying the validity of Mg/Ca records from the WPWP and confirming the absence of a Plio-Pleistocene cooling trend for the WPWP. This finding suggests that the persistent disagreement between foraminifer-based proxies such as Mg/Ca and biomarker data might be caused by different environmental parameters being recorded in the two archives.</p><p> </p><p>References:</p><p>O’Brien CL, Foster GL, Martínez-Botí MA, Abell R, Rae JWB, Pancost RD. High sea surface temperatures in tropical warm pools during the Pliocene. Nature Geoscience. 2014;7(8):606-11.</p><p>Zhang YG, Pagani M, Liu Z. A 12-million-year temperature history of the tropical Pacific Ocean. Science. 2014;344(6179):84-7.</p><p>Dowsett H. Faunal re-evaluation of Mid-Pliocene conditions in the western equatorial Pacific. Micropaleontology. 2007;53(6):447-56.</p><p>Wara MW, Ravelo AC, Delaney ML. Permanent El Nino-like conditions during the Pliocene warm period. Science. 2005;309(5735):758-61.</p><p>Evans D, Brierley C, Raymo ME, Erez J, Müller W. Planktic foraminifera shell chemistry response to seawater chemistry: Pliocene–Pleistocene seawater Mg/Ca, temperature and sea level change. Earth and Planetary Science Letters. 2016;438:139-48.</p>


Author(s):  
Harry J Dowsett ◽  
Marci M Robinson

The Mid-Pliocene is the most recent interval of sustained global warmth, which can be used to examine conditions predicted for the near future. An accurate spatial representation of the low-latitude Mid-Pliocene Pacific surface ocean is necessary to understand past climate change in the light of forecasts of future change. Mid-Pliocene sea surface temperature (SST) anomalies show a strong contrast between the western equatorial Pacific (WEP) and eastern equatorial Pacific (EEP) regardless of proxy (faunal, alkenone and Mg/Ca). All WEP sites show small differences from modern mean annual temperature, but all EEP sites show significant positive deviation from present-day temperatures by as much as 4.4°C. Our reconstruction reflects SSTs similar to modern in the WEP, warmer than modern in the EEP and eastward extension of the WEP warm pool. The east–west equatorial Pacific SST gradient is decreased, but the pole to equator gradient does not change appreciably. We find it improbable that increased greenhouse gases (GHG) alone would cause such a heterogeneous warming and more likely that the cause of Mid-Pliocene warmth is a combination of several forcings including both increased meridional heat transport and increased GHG.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
J. Zinke ◽  
S. A. Browning ◽  
A. Hoell ◽  
I. D. Goodwin

AbstractSmall changes in Pacific temperature gradients connected with the El Niño Southern Oscillation (ENSO) influence the Walker Circulation and are related to global climate anomalies. Therefore, it is of paramount importance to develop robust indices of their past behavior. Here, we reconstruct the difference in sea surface temperature between the west and central Pacific during ENSO, coined the West Pacific Gradient (WPG), based on the Last Millennium Paleo Hydrodynamics Data Assimilation. We show that the WPG tracks ENSO variability and strongly co-varies with the zonal gradient in Pacific sea surface temperature. We demonstrate that the WPG strength is related to significant atmospheric circulation and precipitation anomalies during historical El Niño and La Niña events by magnifying or weakening droughts and pluvials across the Indo-Pacific. We show that an extreme negative WPG coupled to a strong zonal Pacific temperature gradient is associated with enhanced megadroughts in North America between 1400 CE and the late sixteenth century. The twentieth century stands out in showing the most extreme swings between positive and negative WPG conditions over the past Millennium. We conclude that the WPG is a robust index together with ENSO indices to reveal past changes in Pacific zonal sea surface temperature gradient variability.


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