There have been significant changes in sea level over the past two million years, and a complete understanding of natural cycles of change as well as anthropogenic effects is imperative for future ...global development. This book reviews the history of research into these sea-level changes and summarises the methods and analytical approaches used to interpret evidence for sea-level changes. It provides an overview of changing climates during the Quaternary, examines processes responsible for global variability of sea-level records, and presents detailed reviews of sea-level changes for the Pleistocene and Holocene. The book concludes by discussing current trends in sea levels and likely future sea-level changes. This is an important and authoritative resource for academic researchers and graduate and advanced undergraduate students working in tectonics, stratigraphy, geomorphology, physical geography, environmental science and other aspects of Quaternary studies.
The fascinating story of how a harsh terrain that resembled modern Antarctica has been transformed gradually into the forests, grasslands, and wetlands we know today.
The arid region of Central Asia is one of the world's major sources of dust and exerts a significant influence on marine ecosystems, atmospheric carbon dioxide concentrations, the global radiation ...budget, and thus global climate change. Recent global warming has considerably reduced mid-latitude net precipitation by decreasing the latitudinal temperature gradient between the Equator and the Arctic; however, the influence of ice sheet and solar insolation on moisture evolution in Central Asia during the Holocene remains uncertain. Here we show that the relative wet conditions during the early Holocene in northern Central Asia (NCA) were controlled principally by the southern position of the mid-latitude Westerlies under the negative phase of the North Atlantic Oscillation (NAO), a pattern that was influenced by the substantial remnants of the Laurentide and Fennoscandian ice sheets. Subsequent northward migration of the mid-latitude Westerlies under a positive NAO phase resulted in persistent drought conditions during the middle Holocene thermal maximum, due to the combined effects of relatively higher summer insolation and Arctic amplification as well as sea ice loss. In contrast, southward migration of the mid-latitude Westerlies since approximately 3.6 cal kyr BP, driven by declining summer insolation and coincident with the negative NAO phase, increased regional precipitation towards to persistent relatively wet conditions in Central Asia. This reconstructed pattern of Holocene moisture availability contrasts markedly with the increase in precipitation over Central Asia under the current anthropogenically forced warming, thereby justifying further investigation into the multiple forcing mechanisms driving natural and anthropogenic climate change.
Northern peatlands represent one of the largest biospheric carbon (C) reservoirs; however, the role of peatlands in the global carbon cycle remains intensely debated, owing in part to the paucity of ...detailed regional datasets and the complexity of the role of climate, ecosystem processes, and environmental factors in controlling peatland C dynamics. Here we used detailed C accumulation data from four peatlands and a compilation of peatland initiation ages across Alaska to examine Holocene peatland dynamics and climate sensitivity. We find that 75% of dated peatlands in Alaska initiated before 8,600 years ago and that early Holocene C accumulation rates were four times higher than the rest of the Holocene. Similar rapid peatland expansion occurred in West Siberia during the Holocene thermal maximum (HTM). Our results suggest that high summer temperature and strong seasonality during the HTM in Alaska might have played a major role in causing the highest rates of C accumulation and peatland expansion. The rapid peatland expansion and C accumulation in these vast regions contributed significantly to the peak of atmospheric methane concentrations in the early Holocene. Furthermore, we find that Alaskan peatlands began expanding much earlier than peatlands in other regions, indicating an important contribution of these peatlands to the pre-Holocene increase in atmospheric methane concentrations.
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