Recent environmental change at Signy Island, maritime Antarctic: Quantitative lake-sediment studies as a basis for reconstructing catchment ice-cover
A quantitative reconstruction of recent environmental change at Signy Island (60°43'S, 45°38'W), maritime Antarctic, is performed using a model based on physical sediment characteristics. 20th Century climatic warming is the probable cause for recent deglaciation on Signy Island. Proxies i...
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UCL (University College London)
1997
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ftucl:oai:eprints.ucl.ac.uk.OAI2:10106420 2023-12-24T10:11:29+01:00 Recent environmental change at Signy Island, maritime Antarctic: Quantitative lake-sediment studies as a basis for reconstructing catchment ice-cover Noon, Philippa Elizabeth 1997 text https://discovery.ucl.ac.uk/id/eprint/10106420/1/Recent_environmental_change_at.pdf https://discovery.ucl.ac.uk/id/eprint/10106420/ eng eng UCL (University College London) https://discovery.ucl.ac.uk/id/eprint/10106420/1/Recent_environmental_change_at.pdf https://discovery.ucl.ac.uk/id/eprint/10106420/ open Doctoral thesis, UCL (University College London). Earth sciences Catchment ice-cover Thesis Doctoral 1997 ftucl 2023-11-27T13:07:36Z A quantitative reconstruction of recent environmental change at Signy Island (60°43'S, 45°38'W), maritime Antarctic, is performed using a model based on physical sediment characteristics. 20th Century climatic warming is the probable cause for recent deglaciation on Signy Island. Proxies in lake-sediments can be used to model the rates and directions of environmental change. Previous studies have made this link qualitatively. Here, a quantitative link is made between climate and lake-sediment response. The island's 17 freshwater lakes display different characteristics within a small geographical area. Multiple cores from each basin yielded 209 surface-sediment (0-1 cm) samples which were analyzed for their lithology, particle-size and mineral magnetism. Ordination and classification identify relationships between the sediment variables and the environmental factors responsible for within- and between-lake variability. Variance partitioning using a minimum adequate model of 14 significant environmental variables provides insights into the balance of limnological and catchment factors affecting overall sediment character and its component fractions. A portion of unexplained variance suggests that other unmeasured variables also play a role in determining sediment character. Catchment ice-cover is selected for reconstruction on the basis of its gradient length. An inverse regression model is constructed using four variables: % dry weight, % Loss On Ignition, mean particle-size and HARD%. Two methods of reconstruction - Partial Least Squares (PLS) Regression and analogue matching (MAT) are tested with various training-sets. Cross-validated prediction errors are ca. 13%, comparing favourably with historical (1968 AD) records. Calibration is performed at four sites using optimal models to reconstruct ice-cover. The model is a sensitive proxy for erosion. Reconstructions are compared with temperature records and affirm that climatic warming is the most likely cause for observed ice-retreat. Based on simple measures, ... Doctoral or Postdoctoral Thesis Antarc* Antarctic Signy Island University College London: UCL Discovery Antarctic Signy Island ENVELOPE(-45.595,-45.595,-60.708,-60.708) |
institution |
Open Polar |
collection |
University College London: UCL Discovery |
op_collection_id |
ftucl |
language |
English |
topic |
Earth sciences Catchment ice-cover |
spellingShingle |
Earth sciences Catchment ice-cover Noon, Philippa Elizabeth Recent environmental change at Signy Island, maritime Antarctic: Quantitative lake-sediment studies as a basis for reconstructing catchment ice-cover |
topic_facet |
Earth sciences Catchment ice-cover |
description |
A quantitative reconstruction of recent environmental change at Signy Island (60°43'S, 45°38'W), maritime Antarctic, is performed using a model based on physical sediment characteristics. 20th Century climatic warming is the probable cause for recent deglaciation on Signy Island. Proxies in lake-sediments can be used to model the rates and directions of environmental change. Previous studies have made this link qualitatively. Here, a quantitative link is made between climate and lake-sediment response. The island's 17 freshwater lakes display different characteristics within a small geographical area. Multiple cores from each basin yielded 209 surface-sediment (0-1 cm) samples which were analyzed for their lithology, particle-size and mineral magnetism. Ordination and classification identify relationships between the sediment variables and the environmental factors responsible for within- and between-lake variability. Variance partitioning using a minimum adequate model of 14 significant environmental variables provides insights into the balance of limnological and catchment factors affecting overall sediment character and its component fractions. A portion of unexplained variance suggests that other unmeasured variables also play a role in determining sediment character. Catchment ice-cover is selected for reconstruction on the basis of its gradient length. An inverse regression model is constructed using four variables: % dry weight, % Loss On Ignition, mean particle-size and HARD%. Two methods of reconstruction - Partial Least Squares (PLS) Regression and analogue matching (MAT) are tested with various training-sets. Cross-validated prediction errors are ca. 13%, comparing favourably with historical (1968 AD) records. Calibration is performed at four sites using optimal models to reconstruct ice-cover. The model is a sensitive proxy for erosion. Reconstructions are compared with temperature records and affirm that climatic warming is the most likely cause for observed ice-retreat. Based on simple measures, ... |
format |
Doctoral or Postdoctoral Thesis |
author |
Noon, Philippa Elizabeth |
author_facet |
Noon, Philippa Elizabeth |
author_sort |
Noon, Philippa Elizabeth |
title |
Recent environmental change at Signy Island, maritime Antarctic: Quantitative lake-sediment studies as a basis for reconstructing catchment ice-cover |
title_short |
Recent environmental change at Signy Island, maritime Antarctic: Quantitative lake-sediment studies as a basis for reconstructing catchment ice-cover |
title_full |
Recent environmental change at Signy Island, maritime Antarctic: Quantitative lake-sediment studies as a basis for reconstructing catchment ice-cover |
title_fullStr |
Recent environmental change at Signy Island, maritime Antarctic: Quantitative lake-sediment studies as a basis for reconstructing catchment ice-cover |
title_full_unstemmed |
Recent environmental change at Signy Island, maritime Antarctic: Quantitative lake-sediment studies as a basis for reconstructing catchment ice-cover |
title_sort |
recent environmental change at signy island, maritime antarctic: quantitative lake-sediment studies as a basis for reconstructing catchment ice-cover |
publisher |
UCL (University College London) |
publishDate |
1997 |
url |
https://discovery.ucl.ac.uk/id/eprint/10106420/1/Recent_environmental_change_at.pdf https://discovery.ucl.ac.uk/id/eprint/10106420/ |
long_lat |
ENVELOPE(-45.595,-45.595,-60.708,-60.708) |
geographic |
Antarctic Signy Island |
geographic_facet |
Antarctic Signy Island |
genre |
Antarc* Antarctic Signy Island |
genre_facet |
Antarc* Antarctic Signy Island |
op_source |
Doctoral thesis, UCL (University College London). |
op_relation |
https://discovery.ucl.ac.uk/id/eprint/10106420/1/Recent_environmental_change_at.pdf https://discovery.ucl.ac.uk/id/eprint/10106420/ |
op_rights |
open |
_version_ |
1786165667579297792 |