Warmer Pliocene Upwelling Site SST Leads to Wetter Subtropical Coastal Areas: A Positive Feedback on SST

Fu, Minmin; Molnár, Péter; Tziperman, Eli

doi:10.1029/2021pa004357

Cited by 13 publications

(26 citation statements)

References 89 publications

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“…This is supported by the moisture budget analysis presented in Fu et al. (2022), which found that both thermodynamic and dynamic processes contributed to rainfall changes in their simulations. Because SST anomalies in the PRISM3 data set are muted south of Baja California, δ D p is slightly depleted in that region, differing from our record from site 475 (Figure 2, Figure S5 in Supporting Information ).…”

Section: Resultssupporting

confidence: 66%

“…A recent modeling study hypothesized that warmer California margin temperatures in the Pliocene resulted in expanded and enhanced summer convection (Fu et al., 2022). This hypothesis implies that the evolution of the Plio‐Pleistocene NAM should track coastal temperatures on the California Margin.…”

Section: Resultsmentioning

confidence: 99%

“…Warmer subtropical SSTs likely drive higher local fluxes of sensible and latent heat. In addition, the convergent circulation over these warm coastal SSTs imports moist, warm air into this region (Fu et al., 2022). However, wind changes are small in this simulation.…”

Section: Resultsmentioning

confidence: 99%

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Expansion and Intensification of the North American Monsoon During the Pliocene

et al. 2022

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Multiple lines of evidence suggest that southwestern North America (SWNA), like many subtropical continents, was much wetter during the Pliocene epoch, a climate interval featuring reduced ice volume and CO 2 concentrations above preindustrial levels (Figure 1). Sedimentological data document widespread perennial and ephemeral lakes in southern California and Arizona (Pound et al., 2014;Ibarra et al., 2018) (Figure 1), and palynological and macrobotanical evidence from southern California suggests expanded tree cover and the presence of species that today only grow in regions with mesic conditions and summer rainfall (Ballog & Malloy, 1981;Remeika et al., 1988). Faunal remains from Baja California contain Crocodylus spp. fossils, which require freshwater habitats, further suggesting increased water resources in regions that are arid at present (Miller, 1980;Salzmann et al., 2009). At face value, this evidence for a wet Pliocene is at odds with the theoretical and model-derived prediction that regions like SWNA, and subtropical continents more broadly, will continue to dry in coming centuries as a result of elevated greenhouse gases (Byrne & O' Gorman, 2015;Seager et al., 2010).

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Section: Resultssupporting

confidence: 66%

Section: Resultsmentioning

confidence: 99%

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Expansion and Intensification of the North American Monsoon During the Pliocene

et al. 2022

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“…Some have proposed that weaker atmospheric circulation in response to the different ocean surface temperature patterns of the Pliocene reduced meridional and zonal temperature gradients (Molnar and Cane, 2002;Burls and Fedorov, 2017). Another recent hypothesis argues for more enhanced convergent monsoonal circulation developed over late boreal summer due to increased SST in the Pliocene (Fu et al, 2022). Lastly, strengthened southwesterly moisture delivery could have resulted in greater wintertime precipitation that fed the southwest USA lakes (Ibarra et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Paleoclimate controls on lithium enrichment in Great Basin Pliocene-Pleistocene lacustrine clays

Gagnon¹,

Butler²,

Gaviria³

et al. 2023

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Terminal lakes are important archives of continental hydroclimate and in some cases contain important economic resources. Here we present an ~3.6 Myr lacustrine carbonate carbon and oxygen stable isotope record from a Great Basin continental drill core. We pair these measurements with bulk lithium concentrations to reveal a relationship between past climate and lithium enrichment in authigenic lacustrine clays. Further, we explore the possible effects of changing seasonality on the isotope record through the use of paired air mass trajectories and modern isotope data. Our findings show the evolution of the basin's moisture balance over million-year timescales, which we attribute to variations in precipitation seasonality as well as fluctuations in the amount of evaporation associated with changes in atmospheric moisture convergence and divergence. We observe a positive correlation between the oxygen isotope values of the lake carbonate and the bulk sediment lithium concentrations, which we argue is indicative of evapoconcentration of the lake environment and subsequent enrichment of the authigenic clays. Our results suggest a link between past hydroclimate changes and the formation of lithium rich authigenic clays feeding high lithium concentrations in this modern brine aquifer system.

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“…2c), and thereby additionally support the classic picture of a thermally-driven intensification of the mid-Holocene NAM. Furthermore, paleoclimatic investigations of intervals featuring pronounced global changes, such as the Last Glacial Maximum (∼21,000 years before present) and the Pliocene (5.3-3 million years before present) further establish the importance of thermal gradients in modulating NAM variability -be it via atmosphericallymediated meridional temperature contrasts over the North American continent [12] or via coastal land-sea temperature gradients [13].…”

Section: Matters Arisingmentioning

confidence: 99%

Thermal forcing modulates North American Monsoon intensity

Löfverström¹,

Thirumalai²

2022

Preprint

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Understanding the response of monsoon dynamics to climatic forcing is cru- cial for anticipating future shifts in freshwater availability across the global tropics. In this regard, a recent study [1] concludes that precipitation within the core of the North American Monsoon (NAM) should be understood as “convectively enhanced orographic rainfall in a mechanically forced stationary wave, not as a classic, thermally forced tropical monsoon.” Using model simu- lations under altered surface conditions, this study suggests that interactions of the extratropical jet stream with Mexico’s Sierra Madre Occidental (SMO) orography are a first-order control on the NAM under past and future global change. While we agree that the presence of orography enhances rainfall out- side land-sea thermal gradients alone [2], we believe that their experiments and analysis are not adequately designed to refute the central importance of thermally-direct forcing in modulating past and future NAM rainfall.

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Warmer Pliocene Upwelling Site SST Leads to Wetter Subtropical Coastal Areas: A Positive Feedback on SST

Cited by 13 publications

References 89 publications

Expansion and Intensification of the North American Monsoon During the Pliocene

Expansion and Intensification of the North American Monsoon During the Pliocene

Paleoclimate controls on lithium enrichment in Great Basin Pliocene-Pleistocene lacustrine clays

Thermal forcing modulates North American Monsoon intensity

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