Oceanic Impact on European Climate Changes during the Quaternary

Abstract

Integrative studies on paleoclimate variations over oceanic and continental regions are scarce. Though it is known that Earth’s climate is strongly affected by sea-air exchanges of heat and moisture, the role of oceans in climate variations over land remains relatively unexplored. With the aim to unveil this influence, the present work studies major climate oscillations in the North Atlantic region and Europe during the Quaternary, focusing on the oceanic mechanisms that were related to them. During this period, the European climate experienced long-term and wide-amplitude glacial-interglacial oscillations. A covariance between the North Atlantic sea surface temperature and climate signals over the continent is especially observed in Southern Europe. The most severe and drastic climate changes occurred in association to deglaciations, as a consequence of major oceanographic reorganizations that affected atmospheric circulation and ocean-atmosphere heat-flow, which led to variation of temperature and precipitation inland. Most deglaciations began when Northern Hemisphere summer insolation was maximal. Increased heating facilitated the rapid ice-sheet collapse and the massive release of fresh water into the Northern Atlantic, which triggered the weakening or even the shutdown of the North Atlantic Deep Water (NADW) formation. Though the extension of ice-sheets determined the high-latitude European climate, the climate was more influenced by rapid variations of ice volume, deep-water formation rate, and oceanic and atmospheric circulation in middle and subtropical latitudes. In consequence, the coldest stadials in the mid-latitude North Atlantic and Europe since the early Pleistocene coincided with Terminations (glacial/interglacial transitions) and lesser ice-sheet depletions. They were related with decreases in the NADW formation rate that occurred at these times and the subsequent advection of subpolar waters along the western European margin. In Southern Europe, steppe communities substituted temperate forests. Once the freshwater perturbation stopped and the overturning circulation resumed, very rapid and wide-amplitude warming episodes occurred (interstadials). On the continent, raised temperature and precipitations allowed the rapid expansion of moisture-requiring vegetation.

Evidence for strong relations between the upper Tagus loess formation (central Iberia) and the marine atmosphere off the Iberian margin during the last glacial period

“…In fact, corresponding environmental conditions have been documented for periods linked to Greenland stadials and particularly to Heinrich stadials in many places on the Iberian Peninsula (e.g., González-Sampériz et al, 2006, 2010; Sepulchre et al, 2007; Fletcher and Sánchez Goñi, 2008; Vegas et al, 2010; Moreno et al, 2012, 2014; Denniston et al, 2018). Underlying mechanisms are seen in specific land-sea relationships initiated by a decrease of sea surface temperatures linked to a southward incursion of the polar front over the Iberian margin (Roucoux et al, 2005; Sánchez Goñi et al, 2008; Eynaud et al, 2009; Martin-Garcia, 2019). This resulted in reduced moisture uptake off the Iberian coast and thus, reduced moisture transfer over the Iberian Peninsula (e.g., Denniston et al, 2018; Budsky et al, 2019; Torner et al, 2019; see Genty et al, 2003 for SW France).…”

“…Interrelations between ocean surface water, atmosphere, and continental environments play a key role in understanding mechanisms and causes of environmental change in terrestrial ecosystems. For the European continent, the North Atlantic Ocean represents the main source of humidity and precipitation (Trigo et al, 2002), and stipulated temperatures and general climate configurations during the Quaternary (Rahmstorf, 2002; Rousseau et al, 2007; Martin-Garcia, 2019; Pinto and Ludwig, 2020). A general relationship between reduced North Atlantic sea surface temperatures (SST) and colder climate conditions over the continent during glacial/stadial periods has been demonstrated based on vegetation reconstructed from analysis of deep-sea sediment cores along the Iberian margin (Roucoux et al, 2005; Sánchez Goñi et al, 2008, 2018; Margari et al, 2010).…”

Discordant population structure inferred from male- and female-type mtDNAs from Macoma balthica, a bivalve species characterized by doubly uniparental inheritance of mitochondria

“…We can nevertheless note that divergence of populations on either side of the Finistère-Cotentin break occurred between 0.11 to 2.6 Myr ago (Luttikhuisen et al 2003), while population expansion on either side of the break took place 107 to 200 k years ago (depending on the marker and on the clock; table 1, Figures 4, S2). We can therefore tentatively speculate that these populations diverged during the penultimate glacial maximum occurring in the NE Atlantic 140,000 years ago (Martin-Garcia 2019) and expended with secondary contact after that event.…”

“…They are all gonochoric, except for the hermaphroditic mussel Semimytilus algosus (Lubosny et al 2020). More than a simple peculiarity, DUI is suspected to play a role in sex-determination and gonad differentiation (Zouros 2000, Breton et al 2011, Guerra et al 2017, Capt et al 2018, 2019, and could well be involved in population structure through intrinsic (e.g. genetic incompatibilities; Saavedra et al 1996) and extrinsic (e.g.…”

Geographic Genetic Structure of Alectoris chukar in Türkiye: Post-LGM-Induced Hybridization and Human-Mediated Contaminations

“…The ABC analysis estimated that the East–West and Thrace splits occurred simultaneously in the A. chukar populations approximately 12.500 generations ago (48.750 yrBP). This divergence time coincided with the end of a short warming period (45–60 kyBP) in the Würm glacial period [ 151 ]. This climatic period, which started at approximately 50 kyBP, affected the whole area and triggered the retreat of A. chukar populations to lower altitudes or southern latitudes in Türkiye ( Figure 3 c–f).…”