Historical sea-level changes in Australia: Testing the Arctic ice melt hypothesis
Rates of regional and global sea-level rise during the 20th century were faster than in any century over the last 3000 years. Sea-level rise accelerated between ~1850 and ~1950, before greenhouse gases became the dominant forcing agent, which suggests, in part, a natural origin. The acceleration app...
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ftwhiterose:oai:etheses.whiterose.ac.uk:30732 2023-05-15T13:50:33+02:00 Historical sea-level changes in Australia: Testing the Arctic ice melt hypothesis Williams, Sophie Lauren 2021-12 https://etheses.whiterose.ac.uk/30732/ unknown Williams, Sophie Lauren orcid:0000-0002-5122-9492 (2021) Historical sea-level changes in Australia: Testing the Arctic ice melt hypothesis. PhD thesis, University of York. Thesis NonPeerReviewed 2021 ftwhiterose 2023-01-30T21:29:39Z Rates of regional and global sea-level rise during the 20th century were faster than in any century over the last 3000 years. Sea-level rise accelerated between ~1850 and ~1950, before greenhouse gases became the dominant forcing agent, which suggests, in part, a natural origin. The acceleration appears to have been more rapid in the Southern Hemisphere, which, according to geophysical theory, could point at a contribution from Northern Hemisphere land-based ice melt. More high-resolution relative sea level (RSL) reconstructions from the Southern Hemisphere are needed to test this hypothesis, and to complement a limited dataset of proxy and tide-gauge records. This study establishes three new RSL records for southeastern Australia (covering ~1830 – 2018) from analyses of salt-marsh sediments. New training sets of contemporary salt-marsh foraminifera were used for transfer-function analyses to derive palaeo sea-level estimates. High-resolution chronologies were established via Accelerator Mass Spectrometry radiocarbon, radiogenic lead, stable lead isotope ratios and pollen analyses. The new records demonstrate that, when corrected for glacio-isostatic adjustment, sea level has risen by ~0.2 – 0.3 m since ~1830 in southeastern Australia. Rates of sea-level rise were especially high over the first half of the 20th century, with maximum average rates of 4.0 (-0.4 – 7.1 95 % confidence range) mm yr-1, but there is regional variability between sites. A modelled sea-level budget indicates that the acceleration was initially driven by the barystatic component (including gravity, rotation and deformation), but subsequently amplified and driven by sterodynamic sea-level change. An analysis of the sea-level fingerprints of the barystatic component to 20th century global sea-level rise points at a significant input from the Greenland (17 %) and Antarctic Ice Sheets (11 %) as well as glaciers in Alaska (14 %), the Russian Arctic (10 %), western Canada and the US (9 %), south Asia and southern Andes (8 % each). Thesis Antarc* Antarctic Arctic Arctic Foraminifera* glacier* glaciers Greenland Alaska White Rose eTheses Online (Universities Leeds, Sheffield, York) Antarctic Arctic Canada Greenland |
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White Rose eTheses Online (Universities Leeds, Sheffield, York) |
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Rates of regional and global sea-level rise during the 20th century were faster than in any century over the last 3000 years. Sea-level rise accelerated between ~1850 and ~1950, before greenhouse gases became the dominant forcing agent, which suggests, in part, a natural origin. The acceleration appears to have been more rapid in the Southern Hemisphere, which, according to geophysical theory, could point at a contribution from Northern Hemisphere land-based ice melt. More high-resolution relative sea level (RSL) reconstructions from the Southern Hemisphere are needed to test this hypothesis, and to complement a limited dataset of proxy and tide-gauge records. This study establishes three new RSL records for southeastern Australia (covering ~1830 – 2018) from analyses of salt-marsh sediments. New training sets of contemporary salt-marsh foraminifera were used for transfer-function analyses to derive palaeo sea-level estimates. High-resolution chronologies were established via Accelerator Mass Spectrometry radiocarbon, radiogenic lead, stable lead isotope ratios and pollen analyses. The new records demonstrate that, when corrected for glacio-isostatic adjustment, sea level has risen by ~0.2 – 0.3 m since ~1830 in southeastern Australia. Rates of sea-level rise were especially high over the first half of the 20th century, with maximum average rates of 4.0 (-0.4 – 7.1 95 % confidence range) mm yr-1, but there is regional variability between sites. A modelled sea-level budget indicates that the acceleration was initially driven by the barystatic component (including gravity, rotation and deformation), but subsequently amplified and driven by sterodynamic sea-level change. An analysis of the sea-level fingerprints of the barystatic component to 20th century global sea-level rise points at a significant input from the Greenland (17 %) and Antarctic Ice Sheets (11 %) as well as glaciers in Alaska (14 %), the Russian Arctic (10 %), western Canada and the US (9 %), south Asia and southern Andes (8 % each). |
format |
Thesis |
author |
Williams, Sophie Lauren |
spellingShingle |
Williams, Sophie Lauren Historical sea-level changes in Australia: Testing the Arctic ice melt hypothesis |
author_facet |
Williams, Sophie Lauren |
author_sort |
Williams, Sophie Lauren |
title |
Historical sea-level changes in Australia: Testing the Arctic ice melt hypothesis |
title_short |
Historical sea-level changes in Australia: Testing the Arctic ice melt hypothesis |
title_full |
Historical sea-level changes in Australia: Testing the Arctic ice melt hypothesis |
title_fullStr |
Historical sea-level changes in Australia: Testing the Arctic ice melt hypothesis |
title_full_unstemmed |
Historical sea-level changes in Australia: Testing the Arctic ice melt hypothesis |
title_sort |
historical sea-level changes in australia: testing the arctic ice melt hypothesis |
publishDate |
2021 |
url |
https://etheses.whiterose.ac.uk/30732/ |
geographic |
Antarctic Arctic Canada Greenland |
geographic_facet |
Antarctic Arctic Canada Greenland |
genre |
Antarc* Antarctic Arctic Arctic Foraminifera* glacier* glaciers Greenland Alaska |
genre_facet |
Antarc* Antarctic Arctic Arctic Foraminifera* glacier* glaciers Greenland Alaska |
op_relation |
Williams, Sophie Lauren orcid:0000-0002-5122-9492 (2021) Historical sea-level changes in Australia: Testing the Arctic ice melt hypothesis. PhD thesis, University of York. |
_version_ |
1766253675449155584 |