- Email: [email protected]
The early Holocene sea level rise: an episode of major environmental change
Abstracts / Quaternary International 279-280 (2012) 346–461
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we must establish that there is a distinctive Scottish IRD component. Single grain analysis of detrital minerals provides a powerful method to constrain sediment source regions. Although various minerals could be used, we focus on zircon and rutile. The establishment of this approach as a viable means of investigating IRD provenance will provide additional means of investigating ice sheet-climate interactions where no onshore evidence of ice sheet behaviour exists.
on tidewater ice sheets and glaciers; was instrumental in causing the 8200 cooling event; affected the patterns of ocean currents, thereby affecting regional climate; may have influenced volcanic activity; and probably influenced submarine mass movements, perhaps increasing tsunami activity. It will be maintained that the early Holocene sea level rise was not only a consequence of climate change, but also communicated climate change globally.
A COMPARISON OF MULTIPLE METHODS USED TO RECONSTRUCT CLIMATE FIELDS DURING THE COMMON ERA
THE PACE OF MAMMALIAN EVOLUTION: ECOLOGICAL AND MORPHOLOGICAL RESPONSES OF MAMMALS TO CLIMATE CHANGE AT ANNUAL TO MILLENNIAL TIME SCALES
Jason Smerdon. Lamont-Doherty Earth Observatory of Columbia Unive, United States
Felisa Smith. University of New Mexico, United States
E-mail address: [email protected]
E-mail address: [email protected]
Paleoclimatic reconstructions of hemispheric and global surface temperatures during the last millennium vary significantly in their estimates of decadal-to-centennial variability. Although several estimates are based on spatially-resolved climate field reconstruction (CFR) methods, comparisons have been limited to mean Northern Hemisphere temperatures. Spatial skill is explicitly investigated for multiple CFR methods using pseudoproxy experiments (PPEs) derived from two millennial-length coupled Atmosphere-Ocean General Circulation Model (AOGCM) simulations. The adopted pseudoproxy network approximates the spatial distribution of a widely used multi-proxy network and the CFRs target annual temperature variability on a 5-degree latitude-longitude grid. Results indicate that the spatial skill of presently available large-scale CFRs depends on proxy type and location, target data, and the employed reconstruction methodology, although there are general similarities in the performance of all four methods. While results are somewhat sensitive to the ability of the AOGCMs to resolve ENSO and its teleconnections, important areas such as the ocean basins and much of the Southern Hemisphere are reconstructed with particularly poor skill in PPEs with both models.
Arguably the most pressing environmental issue facing society today is that of anthropogenic climate change. With the increasing availability of fine-scale paleoclimate data has come an appreciation for the rapidity and frequency of past shifts in the earth climate system. Yet, the magnitude, timing and nature of biotic responses to such changes remain unclear. Here, we examine the response of small mammals to late Quaternary climate shifts at a variety of temporal scales. We focus on Neotoma (woodrats), a taxa with perhaps the best-resolved paleorecord of the late Quaternary. Neotoma construct middens, or debris piles, which are ubiquitous in the western United States and which under appropriate environmental conditions are preserved for thousands of years. Paleomiddens yield information on morphology, genetics and diet and allow the investigation of responses to climate change over a variety of temporal and spatial scales. We integrate this historical record with museum specimens and modern studies to characterize climatic thresholds leading to local species extirpation and/or range alterations rather than in situ adaptation. Our results demonstrate remarkable congruence across the geographic range at a variety of temporal scales. Chronosequences plotted for various locations demonstrate that woodrats respond as expected on the basis of Bergmann's rule: colder climatic conditions select for larger body size and warmer conditions select for smaller body size. For this genus, at least, morphological adaptation appears to be the dominant mechanism in dealing with changing climatic regimes. Moreover, our work documents the entire range of responses – phenotypic adaptation, migration and species replacements, and local extirpation. We compare our investigations of responses to past Quaternary climate change with those necessary to adapt to predicted levels of anthropogenic warming to assess whether such changes are within animals’ evolutionary capacity.
A REMARKABLE LATE QUATERNARY NEOTECTONIC FEATURE ON THE ISLE OF RAASAY, SCOTLAND, UK David Smith. Oxford University, United Kingdom E-mail address: [email protected]
The Isle of Raasay lies in the Inner Hebrides, western Scotland. The geology of the island is notable for several NE-SW trending faults, one of which is marked by a cliff, up to 100m high, with a detatched screed at its foot. The detatched scree forms a ridge, up to 7m high, which runs for 1.2km along the fault and comprises about 90,000 cubic metres of frost-shattered rock. The ridge is believed to have been formed by episodes of movement along a listric fault ,which included landsliding, during and after the Younger Dryas, perhaps associated with the growth and decay of the Younger Dryas Ice Cap on nearby Skye. Detailed studies of the morphology and sediments of a former lake which existed along the foot of the ridge are described. Radiocarbon dating indicates that the lake drained at about 10,000 cal. BP. Drainage was catastrophic, with about 8 million cubic metres of water discharged in a short time. The cause of the drainage is examined. THE EARLY HOLOCENE SEA LEVEL RISE: AN EPISODE OF MAJOR ENVIRONMENTAL CHANGE David Smith. Oxford University, United Kingdom E-mail address: [email protected]
During the early Holocene, 11,700 - 7,000 cal. BP, the volume of the oceans increased rapidly and the mean global sea surface rose by up to 60m at an average rate of 12mm/year. After about 7,000 BP a sharp change took place and the overall rise was an order of magnitude less. The early Holocene sea level rise is arguably the most striking element of the rise in sea levels during the Last Glacial Termination, a rise which has been described as the most important geological event of recent time. This paper examines the consequences of the early Holocene sea level rise, and illustrations will be given from several areas. It will be maintained that it had a profound effect
PALEOSOLS AT THE KAWAKAWA TEPHRA ISOCHRON: THEIR USE IN PALEOENVIRONMENTAL RECONSTRUCTION FOR NORTHERN SOUTH ISLAND, NEW ZEALAND Carol Smith. Lincoln University, New Zealand E-mail address: [email protected]
Estimates for a global LGM agree on a commencement from 19-23 K BP, however in New Zealand there is a growing body of evidence for an earlier onset of the LGM. The extended LGM (eLGM) in New Zealand is driven by the enhanced westerly flow of the mid-latitude westerlies leading to glacial advances on the west coast of the South Island and increasing aridity on the east coast. There is multi-proxy agreement in New Zealand for 3 advances within the eLGM at approximately 28, 22 and 19 k BP; with a climate amelioration between 25-28 k BP. The Kawakawa tephra (KKT) component of the 27 k cal yr BP Oruanui eruption from the Taupo volcano in central North Island is an important chronostratigraphic marker, appearing towards the start of the climate amelioration within the eLGM. The phreatomagmatic eruption dispersed fall deposits across both the North and South Islands and also the Pacific Ocean. This chronostratigraphic marker thus allows the correlation of paloenvironmental records across varying landscapes and depositional environments. Previous research by the authors using phytolith proxy records infer a dry climate on the east coast while in intermontane basins and upland areas proximal to glaciers, tall tussock grassland dominates. Moreover, changes
455
we must establish that there is a distinctive Scottish IRD component. Single grain analysis of detrital minerals provides a powerful method to constrain sediment source regions. Although various minerals could be used, we focus on zircon and rutile. The establishment of this approach as a viable means of investigating IRD provenance will provide additional means of investigating ice sheet-climate interactions where no onshore evidence of ice sheet behaviour exists.
on tidewater ice sheets and glaciers; was instrumental in causing the 8200 cooling event; affected the patterns of ocean currents, thereby affecting regional climate; may have influenced volcanic activity; and probably influenced submarine mass movements, perhaps increasing tsunami activity. It will be maintained that the early Holocene sea level rise was not only a consequence of climate change, but also communicated climate change globally.
A COMPARISON OF MULTIPLE METHODS USED TO RECONSTRUCT CLIMATE FIELDS DURING THE COMMON ERA
THE PACE OF MAMMALIAN EVOLUTION: ECOLOGICAL AND MORPHOLOGICAL RESPONSES OF MAMMALS TO CLIMATE CHANGE AT ANNUAL TO MILLENNIAL TIME SCALES
Jason Smerdon. Lamont-Doherty Earth Observatory of Columbia Unive, United States
Felisa Smith. University of New Mexico, United States
E-mail address: [email protected]
E-mail address: [email protected]
Paleoclimatic reconstructions of hemispheric and global surface temperatures during the last millennium vary significantly in their estimates of decadal-to-centennial variability. Although several estimates are based on spatially-resolved climate field reconstruction (CFR) methods, comparisons have been limited to mean Northern Hemisphere temperatures. Spatial skill is explicitly investigated for multiple CFR methods using pseudoproxy experiments (PPEs) derived from two millennial-length coupled Atmosphere-Ocean General Circulation Model (AOGCM) simulations. The adopted pseudoproxy network approximates the spatial distribution of a widely used multi-proxy network and the CFRs target annual temperature variability on a 5-degree latitude-longitude grid. Results indicate that the spatial skill of presently available large-scale CFRs depends on proxy type and location, target data, and the employed reconstruction methodology, although there are general similarities in the performance of all four methods. While results are somewhat sensitive to the ability of the AOGCMs to resolve ENSO and its teleconnections, important areas such as the ocean basins and much of the Southern Hemisphere are reconstructed with particularly poor skill in PPEs with both models.
Arguably the most pressing environmental issue facing society today is that of anthropogenic climate change. With the increasing availability of fine-scale paleoclimate data has come an appreciation for the rapidity and frequency of past shifts in the earth climate system. Yet, the magnitude, timing and nature of biotic responses to such changes remain unclear. Here, we examine the response of small mammals to late Quaternary climate shifts at a variety of temporal scales. We focus on Neotoma (woodrats), a taxa with perhaps the best-resolved paleorecord of the late Quaternary. Neotoma construct middens, or debris piles, which are ubiquitous in the western United States and which under appropriate environmental conditions are preserved for thousands of years. Paleomiddens yield information on morphology, genetics and diet and allow the investigation of responses to climate change over a variety of temporal and spatial scales. We integrate this historical record with museum specimens and modern studies to characterize climatic thresholds leading to local species extirpation and/or range alterations rather than in situ adaptation. Our results demonstrate remarkable congruence across the geographic range at a variety of temporal scales. Chronosequences plotted for various locations demonstrate that woodrats respond as expected on the basis of Bergmann's rule: colder climatic conditions select for larger body size and warmer conditions select for smaller body size. For this genus, at least, morphological adaptation appears to be the dominant mechanism in dealing with changing climatic regimes. Moreover, our work documents the entire range of responses – phenotypic adaptation, migration and species replacements, and local extirpation. We compare our investigations of responses to past Quaternary climate change with those necessary to adapt to predicted levels of anthropogenic warming to assess whether such changes are within animals’ evolutionary capacity.
A REMARKABLE LATE QUATERNARY NEOTECTONIC FEATURE ON THE ISLE OF RAASAY, SCOTLAND, UK David Smith. Oxford University, United Kingdom E-mail address: [email protected]
The Isle of Raasay lies in the Inner Hebrides, western Scotland. The geology of the island is notable for several NE-SW trending faults, one of which is marked by a cliff, up to 100m high, with a detatched screed at its foot. The detatched scree forms a ridge, up to 7m high, which runs for 1.2km along the fault and comprises about 90,000 cubic metres of frost-shattered rock. The ridge is believed to have been formed by episodes of movement along a listric fault ,which included landsliding, during and after the Younger Dryas, perhaps associated with the growth and decay of the Younger Dryas Ice Cap on nearby Skye. Detailed studies of the morphology and sediments of a former lake which existed along the foot of the ridge are described. Radiocarbon dating indicates that the lake drained at about 10,000 cal. BP. Drainage was catastrophic, with about 8 million cubic metres of water discharged in a short time. The cause of the drainage is examined. THE EARLY HOLOCENE SEA LEVEL RISE: AN EPISODE OF MAJOR ENVIRONMENTAL CHANGE David Smith. Oxford University, United Kingdom E-mail address: [email protected]
During the early Holocene, 11,700 - 7,000 cal. BP, the volume of the oceans increased rapidly and the mean global sea surface rose by up to 60m at an average rate of 12mm/year. After about 7,000 BP a sharp change took place and the overall rise was an order of magnitude less. The early Holocene sea level rise is arguably the most striking element of the rise in sea levels during the Last Glacial Termination, a rise which has been described as the most important geological event of recent time. This paper examines the consequences of the early Holocene sea level rise, and illustrations will be given from several areas. It will be maintained that it had a profound effect
PALEOSOLS AT THE KAWAKAWA TEPHRA ISOCHRON: THEIR USE IN PALEOENVIRONMENTAL RECONSTRUCTION FOR NORTHERN SOUTH ISLAND, NEW ZEALAND Carol Smith. Lincoln University, New Zealand E-mail address: [email protected]
Estimates for a global LGM agree on a commencement from 19-23 K BP, however in New Zealand there is a growing body of evidence for an earlier onset of the LGM. The extended LGM (eLGM) in New Zealand is driven by the enhanced westerly flow of the mid-latitude westerlies leading to glacial advances on the west coast of the South Island and increasing aridity on the east coast. There is multi-proxy agreement in New Zealand for 3 advances within the eLGM at approximately 28, 22 and 19 k BP; with a climate amelioration between 25-28 k BP. The Kawakawa tephra (KKT) component of the 27 k cal yr BP Oruanui eruption from the Taupo volcano in central North Island is an important chronostratigraphic marker, appearing towards the start of the climate amelioration within the eLGM. The phreatomagmatic eruption dispersed fall deposits across both the North and South Islands and also the Pacific Ocean. This chronostratigraphic marker thus allows the correlation of paloenvironmental records across varying landscapes and depositional environments. Previous research by the authors using phytolith proxy records infer a dry climate on the east coast while in intermontane basins and upland areas proximal to glaciers, tall tussock grassland dominates. Moreover, changes