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Coral reefs are at increasing risk of climate-induced mass bleaching events and mass mortality, yet we do not know how coral reef fish species respond to habitat loss on temporal and spatial scales relevant to climate change. The Red Sea represents an ideal model system to address this given that many reef fish populations persisted during the Last Glacial Maximum despite a significant loss of coral reefs. I studied their demogaphic history to determine the impact of environmentally-induced habitat loss. High-throughput sequencing data combined with an Approximate Bayesian Computation framework (including machine learning techniques) provided sufficient power to estimate population parameters for five reef fish species, Dascyllus abudafur, Dascyllus trimaculatus, Dascyllus marginatus, Pomacanthus maculosus, and Carcharhinus melanopterus. The genetic bottleneck experienced during the Last Glacial Maximum (LGM) was not as small as was expected, highlighting the importance of coral reef habitat and refugia. Studying the impact of the LGM on Dascyllus marginatus, a species with a restricted range in the Indian Ocean, enabled me to use this study design to determine that the refugia was unlikely to have been outside the Red Sea, but rather in-situ. The extensiveness of an external population did not appear to affect the response to habitat loss. Lastly, studying the impact of the LGM on Carcharhinus melanopterus, a larger, more motile shark species, showed a similar pattern of response to habitat loss. I then compared the Red Sea barrier with other biogeographic barriers across the Indo-Pacific; in this case it was stronger than some but not as strong as the Indo-Pacific barrier. Overall, the demographic histories showed a similar and mild response to environmentally-induced habitat loss in the Red Sea across species, albeit with some ecological differences. Two case studies allowed me to uncover more about the unique history of the Red Sea, and provided opportunities to discuss other important questions around coral reef refugia and the biogeography of the Indo-Pacific.

The origins of Clovis technology and the nature and timing of the first populations to reach the Western Hemisphere is one of the most contentious issues in American archaeology. With the rejection of “Clovis-first”, many scholars consider that all colonising migrations followed a route out of Asia and across Beringia into North America. However, none of the technologies present in the far northeast of Asia or Beringia exhibit the manufacturing processes that were used in Clovis. To address this enigma, Stanford and Bradley proposed a radical alternative for the origins of Clovis. They argue that a small pioneering group of Solutreans crossed the Atlantic ice sheets of the LGM and reached the shores of North America. The basis for this argument stems from technological similarities between Clovis and the Solutrean, as well as from climatic, oceanographic, and ethnographic data. Biface manufacture is at the centre of their technological analysis, specifically comparing the reduction sequences of the distinctive Solutrean laurel leaf points and comparing them to Clovis points. This thesis tests the assumption of Stanford and Bradley that the blade manufacturing technologies of Clovis and Solutrean were “virtually identical”. By analysing the blade manufacturing processes from the Solutrean assemblage at Laugerie-Haute and the Clovis assemblage from the Gault site and comparing them to the broader technological patterns present across Eurasia between ~30,000 BP and 11,000 BP; this thesis supports the findings of Stanford and Bradley with the amendment that Clovis specifically intended to produce curved blades but did not use blades to produce projectile points. While convergence cannot be completely ruled out, there is a lack of evidence that would explain the number of similarities in the manufacturing processes. Thus it remains highly likely that interaction across the ice-edge corridor of the Atlantic may have occurred during the LGM.

Hourly winter weather conditions of the Last Glacial Maximum (LGM) are simulated using the Community Climate Model version 3 (CCM3) on a globally resolved T170 (~75 km) grid. This simulation has been run in-tandem with a lower temporally resolved six-year climatological run. The purpose of the study is to determine: (1) whether examination of higher-resolution simulations, on both spatial and temporal scales, can enhance paleometeorological inferences based previously on monthly statistics of model output and (2) whether certain synoptic-scale events, which may have only a modest impact on seasonal statistics, might exert a disproportionate impact on geological climate records. Analysis is focused on changes in wind flow, no analogue climate “states”, synoptic scale events including Northern Hemisphere cyclogenesis, and gust events over glacial dust source regions. Results show a decrease in North Atlantic and increase in North Pacific cyclogenesis during the LGM. Storm trajectories react to the mechanical forcing of the Laurentide Ice Sheet, with Pacific storms tracking over middle Alaska and northern Canada and terminate in the Labrador Sea. The latter result supports observations and other model runs showing a significant reduction in Greenland winter precipitation. The modified Pacific track results in increased precipitation and the delivery of warmer air along the west coast of North America. This could explain “early” glacial warming inferred in this region from proxy climate records, potentially representing instead a natural regional response to ice age boundary conditions. Results also indicate a low variability, “no analogue” region just south of the Laurentide Ice Sheet margin which has appropriate conditions to harbour temperature-sensitive trees west of the Appalachian Mountains. Combined with pollen data, this lends valuable insight into the known disagreement between modern seed dispersal experiments and calculated migration rates. Finally, hourly-scale gust events over dust source regions during the LGM are two to five times greater than the modern, providing a mechanism to help explain the increased glacial dust load seen in the ice cores. Backwards air-parcel trajectories from Antarctic ice core locations show air sources over Patagonia and the Altiplano with some inputs from South Africa agreeing with recent isotopic tracer analyses. Results demonstrate that high temporal and spatial resolution simulations can provide valuable insight to add to the cornucopia of information already available from lower-resolution runs. They can also enhance our interpretation of geological records, which have been previously assumed to record longer time-scale climatological mean-states and thus ignoring any extreme synoptic events which may actually have had a disproportionate impact on their preservation.

Climate states of warm and cold periods have varied on approximately 100,000 year cycles for the last million years. These climate states are represented in similar patterns of global sea level observed in five to seven individual records of sea level over 800-kyr. These records were combined into a 800-kyr long global stack using principal components analysis. A record of δ18O of benthic foraminiferal calcite shows a correlation of 0.9 to the sea level stack (PC1), suggesting a strong sea level influence in the calcite, but a 2-kyr lag with respect to the calcite record suggests that deep ocean temperature precedes the sea level response. Sea level change is estimated to account for nearly 45% of the 100-kyr power of benthic δ18O. The principal component analysis also captured regional variation in the sea level records in PC2 and PC3. Regional variations in δ18O of seawater during the modern/Holocene and Last Glacial Maximum (LGM), respectively, may help us to understand ocean and atmospheric circulation associated with these extreme climate changes. A simple three-box model of the Atlantic Ocean was compared to surface and deep gradients in δ18O of seawater from paleoclimate proxy measurements. First, parameters were tuned to realistic modern values that matched modern δ18O of seawater observations. The estimated LGM parameters did not fit the proxy evidence for a surface gradient change of -0.04 per mil or a vertical gradient change of 0.36 per mil. However, the error in the proxy surface and vertical gradient change estimates is quite large (+/-0.29 per mil and +/-0.14 per mil, respectively). An improved fit to the data was achieved by slowing the overturning circulation while increasing Arctic runoff to a modern value. The results of this study suggest that additional LGM δ18O of seawater measurements are needed to constrain ocean and atmospheric circulation changes.