Diatom-based reconstructions of climate and ocean conditions from Svalbard and Baffin Bay since the Last Glacial Maximum

Mimmi Oksman

Research output: ThesisDoctoral ThesisCollection of Articles

Abstract

The ongoing climate warming has a profound impact on the sensitive Arctic region and the recent changes in Arctic environment have an alarming rate and magnitude. To better understand the changes taking place in the Arctic region, and to project the future impacts of the ongoing climate change, we need to have records of past climate conditions and past interactions between climate system components, which can be obtained using marine proxy records. This work examines ocean surface conditions from high northern latitudes after the Last Glacial Maximum using marine fossil diatom assemblages. Long-term paleoclimatic and -oceanographic records are obtained from northern Svalbard and central-eastern Baffin Bay using quantitative and qualitative diatom analyses, and sediment grain size distribution analysis. An additional focus of this work was to study the ecology of common northern North Atlantic diatom species and define their relationship to environmental variables (aSSTs and sea ice) in order to identify the best indicator species for these environmental variables and to improve their reliability as paleoceanographic indicators. The Baffin Bay study site was investigated for the deglacial period (10−14 kyr BP), and the results suggest a warmer ocean surface in central-eastern Baffin Bay during the cold Younger Dryas period (11.7−12.9 kyr BP) indicating that the ocean was out of phase with atmospheric conditions over Greenland. The warmer conditions were caused by enhanced inflow of Atlantic-sourced waters and increased solar insolation on the Northern Hemisphere, which amplified seasonality over Baffin Bay and had a significant role triggering the ice margin in West Greenland. The paleoceanographic record from northern Svalbard represents the late Holocene (last ca. 4 200 years), and the results show a clear climate shift at 2.5 kyr BP, as the study location changed from stable, glacier-proximal conditions into fluctuating glacier-distal conditions, emphasizing the sensitivity of the Arctic environment to climate oscillations. Understanding diatom species` relationship to environmental variables is essential and this work identifies robust indicators for cold, temperate and warm waters and for sea ice. The results show that not all sea ice-associated species have a statistically significant relationship to sea ice. While this species is often found in sea ice and in the marginal ice zone, its ecology appears to be more complex. The paleoceanographic and –climatic records in this work give new insights to our current knowledge of past climate variability, and reform some of our current understanding of the past climate conditions on a local scale. This work also improves the applicability of the key northern North Atlantic diatom taxa as paleo-indicators, questioning previous knowledge on the ecology of some species and highlighting some important taxonomic issues.
Original languageEnglish
Awarding Institution
  • University of Helsinki
Supervisors/Advisors
  • Weckström, Kaarina, Supervisor
  • Miettinen, Arto, Supervisor, External person
Award date15 Dec 2017
Place of PublicationHelsinki
Publisher
Print ISBNs978-951-51-2937-6
Electronic ISBNs978-951-51-2938-3
Publication statusPublished - 15 Dec 2017
MoE publication typeG5 Doctoral dissertation (article)

Fields of Science

  • 1171 Geosciences

Cite this

@phdthesis{4096202b1a9b46bcb0040eb381680274,
title = "Diatom-based reconstructions of climate and ocean conditions from Svalbard and Baffin Bay since the Last Glacial Maximum",
abstract = "The ongoing climate warming has a profound impact on the sensitive Arctic region and the recent changes in Arctic environment have an alarming rate and magnitude. To better understand the changes taking place in the Arctic region, and to project the future impacts of the ongoing climate change, we need to have records of past climate conditions and past interactions between climate system components, which can be obtained using marine proxy records. This work examines ocean surface conditions from high northern latitudes after the Last Glacial Maximum using marine fossil diatom assemblages. Long-term paleoclimatic and -oceanographic records are obtained from northern Svalbard and central-eastern Baffin Bay using quantitative and qualitative diatom analyses, and sediment grain size distribution analysis. An additional focus of this work was to study the ecology of common northern North Atlantic diatom species and define their relationship to environmental variables (aSSTs and sea ice) in order to identify the best indicator species for these environmental variables and to improve their reliability as paleoceanographic indicators. The Baffin Bay study site was investigated for the deglacial period (10−14 kyr BP), and the results suggest a warmer ocean surface in central-eastern Baffin Bay during the cold Younger Dryas period (11.7−12.9 kyr BP) indicating that the ocean was out of phase with atmospheric conditions over Greenland. The warmer conditions were caused by enhanced inflow of Atlantic-sourced waters and increased solar insolation on the Northern Hemisphere, which amplified seasonality over Baffin Bay and had a significant role triggering the ice margin in West Greenland. The paleoceanographic record from northern Svalbard represents the late Holocene (last ca. 4 200 years), and the results show a clear climate shift at 2.5 kyr BP, as the study location changed from stable, glacier-proximal conditions into fluctuating glacier-distal conditions, emphasizing the sensitivity of the Arctic environment to climate oscillations. Understanding diatom species` relationship to environmental variables is essential and this work identifies robust indicators for cold, temperate and warm waters and for sea ice. The results show that not all sea ice-associated species have a statistically significant relationship to sea ice. While this species is often found in sea ice and in the marginal ice zone, its ecology appears to be more complex. The paleoceanographic and –climatic records in this work give new insights to our current knowledge of past climate variability, and reform some of our current understanding of the past climate conditions on a local scale. This work also improves the applicability of the key northern North Atlantic diatom taxa as paleo-indicators, questioning previous knowledge on the ecology of some species and highlighting some important taxonomic issues.",
keywords = "1171 Geosciences",
author = "Mimmi Oksman",
year = "2017",
month = "12",
day = "15",
language = "English",
isbn = "978-951-51-2937-6",
series = "Department of Geosciences and Geography. A",
publisher = "University of Helsinki",
number = "56",
address = "Finland",
school = "University of Helsinki",

}

Diatom-based reconstructions of climate and ocean conditions from Svalbard and Baffin Bay since the Last Glacial Maximum. / Oksman, Mimmi.

Helsinki : University of Helsinki, 2017. 108 p.

Research output: ThesisDoctoral ThesisCollection of Articles

TY - THES

T1 - Diatom-based reconstructions of climate and ocean conditions from Svalbard and Baffin Bay since the Last Glacial Maximum

AU - Oksman, Mimmi

PY - 2017/12/15

Y1 - 2017/12/15

N2 - The ongoing climate warming has a profound impact on the sensitive Arctic region and the recent changes in Arctic environment have an alarming rate and magnitude. To better understand the changes taking place in the Arctic region, and to project the future impacts of the ongoing climate change, we need to have records of past climate conditions and past interactions between climate system components, which can be obtained using marine proxy records. This work examines ocean surface conditions from high northern latitudes after the Last Glacial Maximum using marine fossil diatom assemblages. Long-term paleoclimatic and -oceanographic records are obtained from northern Svalbard and central-eastern Baffin Bay using quantitative and qualitative diatom analyses, and sediment grain size distribution analysis. An additional focus of this work was to study the ecology of common northern North Atlantic diatom species and define their relationship to environmental variables (aSSTs and sea ice) in order to identify the best indicator species for these environmental variables and to improve their reliability as paleoceanographic indicators. The Baffin Bay study site was investigated for the deglacial period (10−14 kyr BP), and the results suggest a warmer ocean surface in central-eastern Baffin Bay during the cold Younger Dryas period (11.7−12.9 kyr BP) indicating that the ocean was out of phase with atmospheric conditions over Greenland. The warmer conditions were caused by enhanced inflow of Atlantic-sourced waters and increased solar insolation on the Northern Hemisphere, which amplified seasonality over Baffin Bay and had a significant role triggering the ice margin in West Greenland. The paleoceanographic record from northern Svalbard represents the late Holocene (last ca. 4 200 years), and the results show a clear climate shift at 2.5 kyr BP, as the study location changed from stable, glacier-proximal conditions into fluctuating glacier-distal conditions, emphasizing the sensitivity of the Arctic environment to climate oscillations. Understanding diatom species` relationship to environmental variables is essential and this work identifies robust indicators for cold, temperate and warm waters and for sea ice. The results show that not all sea ice-associated species have a statistically significant relationship to sea ice. While this species is often found in sea ice and in the marginal ice zone, its ecology appears to be more complex. The paleoceanographic and –climatic records in this work give new insights to our current knowledge of past climate variability, and reform some of our current understanding of the past climate conditions on a local scale. This work also improves the applicability of the key northern North Atlantic diatom taxa as paleo-indicators, questioning previous knowledge on the ecology of some species and highlighting some important taxonomic issues.

AB - The ongoing climate warming has a profound impact on the sensitive Arctic region and the recent changes in Arctic environment have an alarming rate and magnitude. To better understand the changes taking place in the Arctic region, and to project the future impacts of the ongoing climate change, we need to have records of past climate conditions and past interactions between climate system components, which can be obtained using marine proxy records. This work examines ocean surface conditions from high northern latitudes after the Last Glacial Maximum using marine fossil diatom assemblages. Long-term paleoclimatic and -oceanographic records are obtained from northern Svalbard and central-eastern Baffin Bay using quantitative and qualitative diatom analyses, and sediment grain size distribution analysis. An additional focus of this work was to study the ecology of common northern North Atlantic diatom species and define their relationship to environmental variables (aSSTs and sea ice) in order to identify the best indicator species for these environmental variables and to improve their reliability as paleoceanographic indicators. The Baffin Bay study site was investigated for the deglacial period (10−14 kyr BP), and the results suggest a warmer ocean surface in central-eastern Baffin Bay during the cold Younger Dryas period (11.7−12.9 kyr BP) indicating that the ocean was out of phase with atmospheric conditions over Greenland. The warmer conditions were caused by enhanced inflow of Atlantic-sourced waters and increased solar insolation on the Northern Hemisphere, which amplified seasonality over Baffin Bay and had a significant role triggering the ice margin in West Greenland. The paleoceanographic record from northern Svalbard represents the late Holocene (last ca. 4 200 years), and the results show a clear climate shift at 2.5 kyr BP, as the study location changed from stable, glacier-proximal conditions into fluctuating glacier-distal conditions, emphasizing the sensitivity of the Arctic environment to climate oscillations. Understanding diatom species` relationship to environmental variables is essential and this work identifies robust indicators for cold, temperate and warm waters and for sea ice. The results show that not all sea ice-associated species have a statistically significant relationship to sea ice. While this species is often found in sea ice and in the marginal ice zone, its ecology appears to be more complex. The paleoceanographic and –climatic records in this work give new insights to our current knowledge of past climate variability, and reform some of our current understanding of the past climate conditions on a local scale. This work also improves the applicability of the key northern North Atlantic diatom taxa as paleo-indicators, questioning previous knowledge on the ecology of some species and highlighting some important taxonomic issues.

KW - 1171 Geosciences

M3 - Doctoral Thesis

SN - 978-951-51-2937-6

T3 - Department of Geosciences and Geography. A

PB - University of Helsinki

CY - Helsinki

ER -

Oksman M. Diatom-based reconstructions of climate and ocean conditions from Svalbard and Baffin Bay since the Last Glacial Maximum. Helsinki: University of Helsinki, 2017. 108 p. (Department of Geosciences and Geography. A; 56).