Regional impacts of climate change and its relevance to human evolution

Abstract

The traditional concept of long and gradual, glacial-interglacial climate changes during the Quaternary has been challenged since the 1980s. High temporal resolution analysis of marine, terrestrial and ice geological archives has identified rapid, millennial-to centennial-scale, and large-amplitude climatic cycles throughout the last few million years. These changes were global but have had contrasting regional impacts on the terrestrial and marine ecosystems, with in some cases strong changes in the high latitudes of both hemispheres but muted changes elsewhere. Such a regionalization has produced environmental barriers and corridors that have probably triggered niche contractions/expansions of hominin populations living in Eurasia and Africa. This article reviews the long-and short-timescale ecosystem changes that have punctuated the last few million years, paying particular attention to the environments of the last 650,000 years, which have witnessed key events in the evolution of our lineage in Africa and Eurasia. This review highlights, for the first time, a contemporaneity between the split between Denisovan and Neanderthals, at 650-400 ka, and the strong Eurasian ice-sheet expansion down to the Black Sea. This ice expansion could form an ice barrier between Europe and Asia that may have triggered the genetic drift between these two populations.

Control Mechanisms of Primary Productivity Revealed by Calcareous Nannoplankton From Marine Isotope Stages 12 to 9 at the Shackleton Site (IODP Site U1385)

“…The overall G-I variability observed in the PPP record is superimposed by millennial-scale changes (Figure 3i), concomitant to oscillations in other nannoplankton-based proxy records, SST (Rodrigues et al, 2017) and Mediterranean forest percentage profiles from Site U1385 (Desprat et al, 2017;Oliveira et al, 2016;Sánchez Goñi et al, 2016, 2020Figures 3a and 3c). In general, high PPP values coincide with reduced Mediterranean forest development, (i.e., cold and weak winter precipitation, and low SST during glacials) whereas interglacials are marked by lower PPP values and significant expansion of the Mediterranean forest (i.e., warm and wet winters, and warm SST; Rodrigues et al, 2017;Figures 3a, 3c and 3i).…”

“… Atmospheric and oceanographic proxies at the Site U1385. (a) Relative abundances (%) of mediterranean forest pollen (Desprat et al., 2017; Oliveira et al., 2016; Sánchez Goñi, 2016, 2020). (b) Relative abundances (%) of tetra‐unsaturated alkenone (C 37:4 ; Rodrigues et al., 2017).…”

“…Blue bands represent the Heinrich-type (Ht) events 1 to 4 whereas dashed lines represent other major drops in temperature mentioned in the text. (Desprat et al, 2017;Oliveira et al, 2016;Sánchez Goñi, 2016;2020). (b) % tetra-unsaturated alkenone (C37:4; Rodrigues et al, 2017).…”

“…GONZÁLEZ-LANCHAS ET AL. (Desprat et al, 2017;Oliveira et al, 2016;Sánchez Goñi, 2016, 2020. (b) Relative abundances (%) of tetra-unsaturated alkenone (C 37:4 ; Rodrigues et al, 2017).…”

“…Here, we present high‐resolution calcareous nannofossil records to reconstruct variations in primary productivity and corresponding changes in surface‐water dynamics between MIS 12 and MIS 9 (450–320 ka). These data are compared with marine proxies such as alkenone concentration and U k´ 37 ‐ Sea Surface Temperature (SST) (Rodrigues et al., 2017) and benthic and planktonic stable oxygen isotope records (Hodell et al., 2015) and terrestrial atmospherically driven vegetation changes from Site U1385 (Desprat et al., 2017; Oliveira et al., 2016; Sánchez‐Goñi et al., 2016, 2020). This multi‐proxy approach provides an excellent opportunity to evaluate the influence of both atmospheric and hydrological forcing in response to climate oscillations on marine primary productivity in the context of G‐I to suborbital/millennial‐scale variability.…”