Miocene Evolution of North Atlantic Sea Surface Temperature

Abstract

We reconstruct sea surface temperatures (SSTs) at Deep Sea Drilling Project Site 608 (42.836°N, 23.087°), north of the Azores Front, and Ocean Drilling Program Site 982 (57.516°N, 15.866°), under the North Atlantic Current, in order to track Miocene (23.1-5.3 Ma) development of North Atlantic surface waters. Mean annual SSTs from TEX 86 and U K′37 proxy estimates at both sites were 10-15°C higher than modern through the Miocene Climatic Optimum (17-14.5 Ma). During the global cooling of the Middle Miocene Climate Transition (~14.5-12.5 Ma), SSTs at midlatitude Site 608 cooled by~6°C, whereas high-latitude Site 982 cooled by only~2°C, resulting in an~4 Myr collapse of the SST gradient between the two sites. This regional pattern is inconsistent with an increased latitudinal surface temperature gradient, as generally associated with global cooling episodes linked to decreasing pCO 2 levels. Instead, the pattern is best explained by enhanced ocean heat transport into the high-latitude North Atlantic superimposed on the global cooling trend, probably due to enhanced Atlantic meridional overturning circulation and/or a stronger North Atlantic Current. During global late Miocene cooling (~8-7 Ma), surface waters cooled bỹ 6°C at Site 982 while minimal change occurred at Site 608, reestablishing the North Atlantic SST gradient. The collapse and reemergence of the SST gradient between the middle-and high-latitude North Atlantic suggests that interaction between changes in regional ocean circulation and the global response to changes in greenhouse gas concentration was important in Miocene climate evolution.

Simulating Miocene Warmth: Insights From an Opportunistic Multi‐Model Ensemble (MioMIP1)

“…Oxygen isotope records of benthic foraminifera (δ 18 O c ) show that peak Miocene warmth and minimum ice volume occurred in the Early to Middle Miocene (16.75–14.5 Ma), known as the Miocene Climate Optimum (MCO) (Figure 1). During the MCO, current reconstructions suggest that sea surface temperatures (SSTs) were 8°C–10°C warmer than present in the high southern latitudes (Shevenell et al., 2004) and 10°C–15°C warmer in the high northern latitudes (Super et al., 2020), while deep ocean temperatures were ∼5°C–8°C warmer (Lear et al., 2000, 2015), leading to an estimated global mean surface temperature anomaly of 7.6°C 2.3°C compared to preindustrial (Goldner et al., 2014). The warmer conditions shifted the bioclimatic zones poleward (Pound et al., 2012).…”

Warm High‐Elevation Mid‐Latitudes During the Miocene Climatic Optimum: Paleosol Clumped Isotope Temperatures From the Northern Rocky Mountains, USA

“…17–15 Ma) warming period during the Miocene, reflects the last long‐term interruption of Cenozoic cooling (De Vleeschouwer et al., 2017; Zachos et al., 2001, 2008). Elevated pCO 2 levels during the MCO (Breecker & Retallack, 2014; Foster et al., 2012; Kürschner et al., 2008; Sosdian et al., 2018; Steinthorsdottir et al., 2021; Super et al., 2018; Zhang et al., 2013) are in line with elevated temperatures on land (e.g., Böhme, 2003; Ivanov et al., 2011; Larsson et al., 2011; Methner et al., 2020; Pound et al., 2012; Wolfe, 1994) and in the oceans (e.g., Lear et al., 2015; Sosdian et al., 2020; Super et al., 2020, 2018; Zhang et al., 2013). Benthic foraminifera oxygen isotope (δ 18 O) values document periods of rather rapid temperature change and continental glaciation during the overall warm MCO (MI‐2 interval) and into the subsequent Middle Miocene Climate Transition (MMCT; MI‐3a and MI‐3b intervals) (Diester‐Haass et al., 2009; Flower & Kennett, 1995; Holbourn et al., 2013, 2015; Kochhann et al., 2016; Miller et al., 1991; Miller & Mountain, 1996; Tian et al., 2013).…”

Middle Miocene Temperature and Productivity Evolution at a Northeast Atlantic Shelf Site (IODP U1318, Porcupine Basin): Global and Regional Changes

“…ODP 982, Super et al, 2018Super et al, , 2020. The analyses of Miocene climate records from different locations in the North Atlantic may help us understand the role of regional variability, superimposed on the global trends and drivers of climate change.…”

“…confidence interval based on a determination of a multinomial distribution for multiple taxa (following Heslop et al, 2011). (Super et al, 2018), ODP Site 982 (Super et al, 2020) and IODP Site U1318 plotted using BAYSPAR calibration (Tierney and Tingley, 2015) for the interval 16.6 -12.7 Ma. CO2 (μatm) concentrations based on stomata (Kürschner et al, 2008), alkenones (Zhang et al, 2013), paleosols (Retallack, 2009) and Boron isotopes (from Sosdian et al, 2018;.…”