- Email: [email protected]
Glacier sensitivity to changes in climate – past and future
418
Abstracts / Quaternary International 279-280 (2012) 346–461
POST-GLACIAL SPATIAL AND TEMPORAL PATTERNS OF PEATLAND INITIATION AND FORMATION PROCESSES OVER THE BOREAL NORTHERN EUROPE AND NORTH-AMERICA Meri Ruppel. University of Helsinki/Department of Environmental, Finland E-mail address: meri.ruppel@helsinki.fi
Peatlands are important ecosystems in the northern hemisphere where they cover vast areas, in some parts even two thirds of the land area. Their role in global biogeochemical processes is acknowledged and, accordingly, increasing interest to understand peatland dynamics - past, modern and future - is rising. Chronological and geographical data of peatland initiation has, however, been scattered, hampering the establishment of a reliable view of post glacial spatio-temporal peatland development patterns. Here we present, for the first time, a comprehensive broad-scale account of the initiation and development histories of peatlands in boreal northern Europe and North-America. We used a data set of ca. 1500 basal peat ages from ca. 700 peatlands and literature-based sediment type interpretations to investigate peatland formation pathways. This large data set provides an extensive spatio-temporal view of the peatland formation processes during the Holocene. Based on the current data set the prevailing conception of the relative proportions of different initiation processes will change. For instance, in northern Europe and in North-America, peatland formation through lake infilling has been more common (ca. 30 %), than previously estimated. Moreover, the data set suggests that there does not exist any explicit link between any peatland formation process and climate, although paludification and subsequent lateral expansion of peatlands have been slightly more intensive during wet climate phases. It also has to be kept in mind that the gathered data may contain many error sources related to e.g. chronological control or identification of the sediment type underlying the basal peat. Nevertheless, this novel data set shows that in the past all peatland formation pathways widely co-occurred, which information can set a challenge for the peatland modeling community.
involvement in the region encompasses both Spanish and British interests and is complex. Belize forms part of the Yucatán Peninsula, a region that has been the subject of much research due to the possible link between climatic variation and associated shifts in the Maya culture and populations. Archaeological, paleolimnological and palynological data sets extend from 1500 BC to AD 1500 and show that Lamanai has been continuously occupied throughout a period of apparent ‘collapse’ discussed in other research in the wider Yucatán region, and was occupied at the time of the first European contact. However, there is little land-use and climate change data from the site; or northern Belize in general, since AD 1500. Exploration of documentary and instrumental sources in conjunction with natural proxy data already available afford insight into the relative environmental impacts of pre- and post conquest societies in this region, contributing to debates surrounding the environmental impacts of the native population of the Americas prior to 1492, and to a wider understanding of human and climatic interaction in this part of Mesoamerica. Documentary sources to be consulted include those resulting from British involvement in Belize (ca. 1770s-1980s) e.g. maps, Governor's reports and correspondence, shipping returns and blue book statistics. Archives of various missionary societies working in the region during the 19th century including correspondence from those working in Belize will also be exploited to extract direct and indirect references to local climate information This research seeks to highlight how instrumental, historical and natural proxies from both local and regional scales and high and low resolutions can be combined to provide the most complete and integrated climate chronology possible. ENHANCING THE CHRONOLOGY OF ARCHAEOLOGICAL SEQUENCES IN CYRENAICA, NORTHERN LIBYA, USING SMALL ALIQUOT AND SINGLE GRAIN OPTICALLY STIMULATED LUMINESCENCE (OSL) DATING OF FINE SAND Natalie Russell. Royal Holloway, University of London, United Kingdom E-mail address: [email protected]
GLACIER SENSITIVITY TO CHANGES IN CLIMATE – PAST AND FUTURE Summer Rupper. Brigham Young University, United States E-mail address: [email protected]
A suite of general circulation model (GCM) simulations and a glacier equilibrium line altitude (ELA) model are used to test the sensitivity of the glaciers of High Asia to simulated climate changes at the Last Glacial Maximum (LGM), mid-Holocene (6 ka), and future climate scenarios (2xCO2). Both intermodel differences as well as comparisons to recent and reconstructed glacier changes highlight regions where model uncertainty is greatest, and provide a guide to focus field research where paleoclimate proxies and glacial histories are crucial in order to further constrain GCMs. In particular, the southeastern Himalaya is a region where intermodel variability is extremely high, yet few paleoclimate proxies and glacier studies are available to help constrain the models. This is an example where numerical modelling efforts can strongly inform fieldwork. In addition, the suite of model simulations provides a test of glacier sensitivity to changes in boundary conditions. The results of this study highlight temperature changes as being the most important influence on glacier ELA for much of Central Asia and for all climate scenarios – past and future. However, this sensitivity is strongly dependent upon whether ablation is dominated by melt or sublimation. The ablation regime changes as boundary conditions change, therefore the glacier sensitivity to changes in climate forcings in any given region is not stationary in time. These results suggest that glacier sensitivity determined for modern climatic conditions may not be applicable to past climates or future climate scenarios.
The internationally significant archaeological sequences and climatic records preserved in the landscape surrounding the Haua Fteah site in the Cyrenaican region of Northern Libya contain an abundance of climatic proxies. While the chronology for these sequences is at present poorly understood, these records offer the opportunity to further our understanding of the local occupation sequence, and its relationship to the long term environmental and human history of the southern Mediterranean region. This study reports the results of Optically Stimulated Luminescence (OSL) dating of fine sand-sized quartz from the Haua Fteah and surrounding region. Fine sands (60-125 mm) were used due to the paucity of coarser grained material in all samples. Luminescence properties of each sample were initially investigated to determine the optimal measurement conditions, prior to equivalent dose determinations, which were performed using small aliquots and hand-picked individual grains. Smallaliquot and single-grain datasets yield comparable results, indicating that the former approach may be suitable for application to the majority of samples in this study. However, some discrepancies between the two techniques do exist. We discuss the implications of these results, with specific focus on the potential for using fine-sands in future dating work in Cyrenaica. OPTICALLY STIMULATED LUMINESCENCE (OSL) DATING OF ADRIATIC MARINE SEDIMENTS: A TEST OF THE METHOD USING THE NEAPOLITAN YELLOW TUFF TEPHRA HORIZON AS AN INDEPENDENT AGE CONTROL Natalie Russell. Royal Holloway, University of London, United Kingdom
AN INTEGRATED APPROACH TO A MULTI-PROXY CLIMATE RECONSTR UCTION FROM LAMANAI, BELIZE, CENTRAL AMERICA Elizabeth Rushton. University of Nottingham, United Kingdom E-mail address: [email protected]
Lamanai, northern Belize (formally British Honduras), is a site of climatic variability, ecological diversity and Mayan occupation. European colonial
E-mail address: [email protected]
Optically Stimulated Luminescence (OSL) dating currently remains relatively untested in the marine realm, despite offering a potential dating range of c. 175ka, at a precision of c. 5-10%. The Adriatic Sea represents an ideal region for testing the potential of new chronological techniques, since it experiences high sedimentation rates, strong regional seasonality, and a large suite of published palaeoenvironmental proxy records, which
Abstracts / Quaternary International 279-280 (2012) 346–461
POST-GLACIAL SPATIAL AND TEMPORAL PATTERNS OF PEATLAND INITIATION AND FORMATION PROCESSES OVER THE BOREAL NORTHERN EUROPE AND NORTH-AMERICA Meri Ruppel. University of Helsinki/Department of Environmental, Finland E-mail address: meri.ruppel@helsinki.fi
Peatlands are important ecosystems in the northern hemisphere where they cover vast areas, in some parts even two thirds of the land area. Their role in global biogeochemical processes is acknowledged and, accordingly, increasing interest to understand peatland dynamics - past, modern and future - is rising. Chronological and geographical data of peatland initiation has, however, been scattered, hampering the establishment of a reliable view of post glacial spatio-temporal peatland development patterns. Here we present, for the first time, a comprehensive broad-scale account of the initiation and development histories of peatlands in boreal northern Europe and North-America. We used a data set of ca. 1500 basal peat ages from ca. 700 peatlands and literature-based sediment type interpretations to investigate peatland formation pathways. This large data set provides an extensive spatio-temporal view of the peatland formation processes during the Holocene. Based on the current data set the prevailing conception of the relative proportions of different initiation processes will change. For instance, in northern Europe and in North-America, peatland formation through lake infilling has been more common (ca. 30 %), than previously estimated. Moreover, the data set suggests that there does not exist any explicit link between any peatland formation process and climate, although paludification and subsequent lateral expansion of peatlands have been slightly more intensive during wet climate phases. It also has to be kept in mind that the gathered data may contain many error sources related to e.g. chronological control or identification of the sediment type underlying the basal peat. Nevertheless, this novel data set shows that in the past all peatland formation pathways widely co-occurred, which information can set a challenge for the peatland modeling community.
involvement in the region encompasses both Spanish and British interests and is complex. Belize forms part of the Yucatán Peninsula, a region that has been the subject of much research due to the possible link between climatic variation and associated shifts in the Maya culture and populations. Archaeological, paleolimnological and palynological data sets extend from 1500 BC to AD 1500 and show that Lamanai has been continuously occupied throughout a period of apparent ‘collapse’ discussed in other research in the wider Yucatán region, and was occupied at the time of the first European contact. However, there is little land-use and climate change data from the site; or northern Belize in general, since AD 1500. Exploration of documentary and instrumental sources in conjunction with natural proxy data already available afford insight into the relative environmental impacts of pre- and post conquest societies in this region, contributing to debates surrounding the environmental impacts of the native population of the Americas prior to 1492, and to a wider understanding of human and climatic interaction in this part of Mesoamerica. Documentary sources to be consulted include those resulting from British involvement in Belize (ca. 1770s-1980s) e.g. maps, Governor's reports and correspondence, shipping returns and blue book statistics. Archives of various missionary societies working in the region during the 19th century including correspondence from those working in Belize will also be exploited to extract direct and indirect references to local climate information This research seeks to highlight how instrumental, historical and natural proxies from both local and regional scales and high and low resolutions can be combined to provide the most complete and integrated climate chronology possible. ENHANCING THE CHRONOLOGY OF ARCHAEOLOGICAL SEQUENCES IN CYRENAICA, NORTHERN LIBYA, USING SMALL ALIQUOT AND SINGLE GRAIN OPTICALLY STIMULATED LUMINESCENCE (OSL) DATING OF FINE SAND Natalie Russell. Royal Holloway, University of London, United Kingdom E-mail address: [email protected]
GLACIER SENSITIVITY TO CHANGES IN CLIMATE – PAST AND FUTURE Summer Rupper. Brigham Young University, United States E-mail address: [email protected]
A suite of general circulation model (GCM) simulations and a glacier equilibrium line altitude (ELA) model are used to test the sensitivity of the glaciers of High Asia to simulated climate changes at the Last Glacial Maximum (LGM), mid-Holocene (6 ka), and future climate scenarios (2xCO2). Both intermodel differences as well as comparisons to recent and reconstructed glacier changes highlight regions where model uncertainty is greatest, and provide a guide to focus field research where paleoclimate proxies and glacial histories are crucial in order to further constrain GCMs. In particular, the southeastern Himalaya is a region where intermodel variability is extremely high, yet few paleoclimate proxies and glacier studies are available to help constrain the models. This is an example where numerical modelling efforts can strongly inform fieldwork. In addition, the suite of model simulations provides a test of glacier sensitivity to changes in boundary conditions. The results of this study highlight temperature changes as being the most important influence on glacier ELA for much of Central Asia and for all climate scenarios – past and future. However, this sensitivity is strongly dependent upon whether ablation is dominated by melt or sublimation. The ablation regime changes as boundary conditions change, therefore the glacier sensitivity to changes in climate forcings in any given region is not stationary in time. These results suggest that glacier sensitivity determined for modern climatic conditions may not be applicable to past climates or future climate scenarios.
The internationally significant archaeological sequences and climatic records preserved in the landscape surrounding the Haua Fteah site in the Cyrenaican region of Northern Libya contain an abundance of climatic proxies. While the chronology for these sequences is at present poorly understood, these records offer the opportunity to further our understanding of the local occupation sequence, and its relationship to the long term environmental and human history of the southern Mediterranean region. This study reports the results of Optically Stimulated Luminescence (OSL) dating of fine sand-sized quartz from the Haua Fteah and surrounding region. Fine sands (60-125 mm) were used due to the paucity of coarser grained material in all samples. Luminescence properties of each sample were initially investigated to determine the optimal measurement conditions, prior to equivalent dose determinations, which were performed using small aliquots and hand-picked individual grains. Smallaliquot and single-grain datasets yield comparable results, indicating that the former approach may be suitable for application to the majority of samples in this study. However, some discrepancies between the two techniques do exist. We discuss the implications of these results, with specific focus on the potential for using fine-sands in future dating work in Cyrenaica. OPTICALLY STIMULATED LUMINESCENCE (OSL) DATING OF ADRIATIC MARINE SEDIMENTS: A TEST OF THE METHOD USING THE NEAPOLITAN YELLOW TUFF TEPHRA HORIZON AS AN INDEPENDENT AGE CONTROL Natalie Russell. Royal Holloway, University of London, United Kingdom
AN INTEGRATED APPROACH TO A MULTI-PROXY CLIMATE RECONSTR UCTION FROM LAMANAI, BELIZE, CENTRAL AMERICA Elizabeth Rushton. University of Nottingham, United Kingdom E-mail address: [email protected]
Lamanai, northern Belize (formally British Honduras), is a site of climatic variability, ecological diversity and Mayan occupation. European colonial
E-mail address: [email protected]
Optically Stimulated Luminescence (OSL) dating currently remains relatively untested in the marine realm, despite offering a potential dating range of c. 175ka, at a precision of c. 5-10%. The Adriatic Sea represents an ideal region for testing the potential of new chronological techniques, since it experiences high sedimentation rates, strong regional seasonality, and a large suite of published palaeoenvironmental proxy records, which