Fossil leaf wax hydrogen isotopes reveal variability of Atlantic and Mediterranean climate forcing on the southeast Iberian Peninsula between 6000 to 3000 cal. BP

Abstract

Many recently published papers have investigated the spatial and temporal manifestation of the 4.2 ka BP climate event at regional and global scales. However, questions with regard to the potential drivers of the associated climate change remain open. Here, we investigate the interaction between Atlantic and Mediterranean climate forcing on the south-eastern Iberian Peninsula during the mid- to late Holocene using compound-specific hydrogen isotopes from fossil leaf waxes preserved in marine sediments. Variability of hydrogen isotope values in the study area is primarily related to changes in the precipitation source and indicates three phases of increased Mediterranean sourced precipitation from 5450 to 5350 cal. BP, from 5150 to 4300 cal. BP including a short-term interruption around 4800 cal. BP, and from 3400 to 3000 cal. BP interrupted around 3200 cal. BP. These phases are in good agreement with times of prevailing positive modes of the North Atlantic Oscillation (NAO) and reduced storm activity in the Western Mediterranean suggesting that the NAO was the dominant modulator of relative variability in precipitation sources. However, as previously suggested other modes such as the Western Mediterranean Oscillation (WeMO) may have altered this overall relationship. In this regard, a decrease in Mediterranean moisture source coincident with a rapid reduction in warm season precipitation during the 4.2 ka BP event at the south-eastern Iberian Peninsula might have been related to negative WeMO conditions.

Paleohydrological dynamics in the Western Mediterranean during the last glacial cycle

“…Although both records display overall similar trends, the relative isotopic enrichment of the LdRS record with respect to the Padul-15-05 core can be explained by specific features of its catchment, covered with snow most of the year, southward oriented, and with scarce patchy tundra vegetation only growing during the late spring-summer under the influence of warm season precipitation (high Mediterranean moisture contribution) along with the isotopic enrichment of catchment waters. Additionally, another recent study based on hydrogen isotopes of leaf waxes from a sediment core in the Alborán Sea described highfrequency changes in the source of precipitation in southern Iberia related to the interaction between Atlantic and Mediterranean atmospheric dynamics (Schirrmacher et al, 2020).…”

Women in Biogeochemical Dynamics Research: 2022

“…However, the use of these compounds requires a comprehensive characterization of modern plants composition and understanding of their respond to the prevailing climate and environment factors (e.g., Bush and McInerney, 2013;Howard et al, 2018;Wang et al, 2018). The characterization of modern leaf wax compositions in the IP is still understudied (Ferreira et al, 2007;Ortiz et al, 2010Ortiz et al, , 2011Ortiz et al, , 2016López-Días et al, 2013), despite the increasing number of past reconstructions using these compounds in both marine and lacustrine records (e.g., Jambrina-Enríquez et al, 2016;Taylor et al, 2018;Schirrmacher et al, 2020;Toney et al, 2020). Here, we focus on leaf wax n-alkanes, n-alkyl lipids with the general formula of C n H 2n+2 (where n is the carbon number in the chemical chain), synthesized by plants to act as a protective barrier from the external environment and prevent water loss (Eglinton and Hamilton, 1967;Cranwell et al, 1987;Post-Beittenmiller, 1996;Shepherd and Griffiths, 2006).…”

“…The moisture-rich westerlies are predominant during winters and show a gradual D-depletion from the coast inland (Carreira et al, 2009). The atmospheric moisture sources of this part of the IP are almost exclusively derived from the prevailing westerly Atlantic air masses (Carreira et al, 2009;Cortesi et al, 2013;Thatcher et al, 2020), contrasting with other regions, such as the southeastern, which can also be significantly influenced by Mediterranean sources (Cortesi et al, 2013;Taylor et al, 2018;Schirrmacher et al, 2020;Toney et al, 2020). The high-altitude setting of Serra da Estrela results in temperature being an important driver of moisture condensation and the δD value of precipitation (δD prc ) (Carreira et al, 2009;Oliveira and Lima, 2010).…”

Leaf wax biomarkers of a high-mountain lake area in western iberia—Implications for environmental reconstructions

“…The moisture-rich westerlies are predominant during winters and show a gradual D-depletion from the coast inland (Carreira et al, 2009). The atmospheric moisture sources of this part of the IP are almost exclusively derived from the prevailing westerly Atlantic air masses (Carreira et al, 2009;Cortesi et al, 2013;Thatcher et al, 2020), contrasting with other regions, such as the southeastern, which can also be significantly influenced by Mediterranean sources (Cortesi et al, 2013;Taylor et al, 2018;Schirrmacher et al, 2020;Toney et al, 2020). The high-altitude setting of Serra da Estrela results in temperature being an important driver of moisture condensation and the δD value of precipitation (δD prc ) (Carreira et al, 2009;Oliveira and Lima, 2010).…”

“…However, the use of these compounds requires a comprehensive characterization of modern plants composition and understanding of their respond to the prevailing climate and environment factors (e.g., Bush and McInerney, 2013;Howard et al, 2018;Liu et al, 2018;Wang et al, 2018). The characterization of modern leaf wax compositions in the IP is still understudied (Ferreira et al, 2007;Ortiz et al, 2010Ortiz et al, , 2011Ortiz et al, , 2016López-Días et al, 2013), despite the increasing number of past reconstructions using these compounds in both marine and lacustrine records (e.g., Jambrina-Enríquez et al, 2016;Taylor et al, 2018;Schirrmacher et al, 2020;Toney et al, 2020). Here, we focus on leaf wax n-alkanes, n-alkyl lipids with the general formula of C n H 2n+2 (where n is the carbon number in the chemical chain), synthesized by plants to act as a protective barrier from the external environment and prevent water loss (Eglinton and Hamilton, 1967;Cranwell et al, 1987;Post-Beittenmiller, 1996;Shepherd and Griffiths, 2006).…”