Our Research Agenda
Central research objective: to assess large scale ocean-atmosphere climate dynamics during past warm climates to improve our understanding of future climate change.
To address this objective the MorPalaeo Lab research agenda concentrates on two avenues:
(1) Refining techniques in palaeoceanography to provide more reliable reconstructions of the extent and magnitude of past changes in climate, and
(2) Applying a multiproxy approach to past climate reconstructions, including isotope and trace metal geochemistry, foraminiferal assemblage counts, and the analysis of marine sediments.
Current Research Projects
Signal Tracking to unveil Arctic Climate variability
Dr. Audrey Morley
Our understanding of critical climate tipping points and their impact on future Arctic and global climate remains limited due to the shortness of our observational records and our inability to quantify past changes in sea surface temperatures and the carbonate system in Arctic or Subarctic Oceans. SiTrAc addresses this critical gap by pioneering a new holistic multidisciplinary approach to palaeoceanographic proxy development that considers foraminifera as a living organism and not just as a proxy carrier. Using innovative biogeochemical techniques and micro-structural analyses of polar foraminifera Neogloboquadrina pachyderma (NP), which is the dominant and often only species present in surface waters below 4C, SiTrAc will track essential climate variables via the living proxy into the archive (i.e., marine sediments). Further, SiTrAc's unique research strategy will quantify biological and physiochemical processes, that influence how geochemical tracers are recorded, at the time of proxy development and thereby fundamentally advance our understanding of proxies and Arctic climate. SiTrAc provides the critical basis for testing future hypotheses, inside and outside of the Arctic, related to mechanisms controlling climate tipping points globally in the past, present, and future.
Funded through the
Expedition CE23011 to the Labrador and Nordic Seas
Chief Scientist: Dr. Audrey Morley
Expedition CE23011 on RV Celtic Explorer to the Labrador and Nordic Seas is scheduled from July 21st 2023 to August 21st 2023 and directly facilitates the scientific objectives of Project SiTrAc. These are as follows:
Monitor current hydrographic conditions in Arctic and sub-Arctic Seas.
Monitor Deepwater exchange between the Arctic and North Atlantic.
Modern major element and isotope cycling in Polar seas.
Determine Biogeochemical processes in the upper ocean.
Signal tracking of Essential Climate Variables into the live Neogloboquadrina pachyderma (NP).
Determine the impact of dissolution and ocean acidification on geochemical proxies and microstructural markers preserved in dead NP sinking in the water column
Determine the impact of early diagensis on geochemical proxies and microstructural markers preserved in NP deposited on the Sea floor
Determine the signal contribution of vital effects and diagensisis on ECV recorded past climate archives
Developing novel chronostratigraphic approaches to link the modern ocean to the past.
Funded through the
Decoding Arctic Climate Change: From Archive to Insight
Dr. Elwyn de la Vega & Dr. Audrey Morley
In conjunction with Cruise CIAAN to the Nordic Seas in August-September 2020 on RV Celtic Explorer, project ACCAI aims to develop new palaeoceanographic tools that will enable us to monitor long-term processes in atmosphere-ocean CO2 exchange and climate change. Specifically, ACCAI intends to determine how the signature of Essential Climate Variables (e.g. temperature, salinity, and the carbonate system) are recorded in the Nordic Seas and transferred into geologic archives (marine sediments). To track the climate signal from the water to the archive we will combine a hydrographic survey in the Nordic Seas with the collection of live foraminifera collected via plankton tows and recently deposited foraminifera in surface marine sediments. Using new developments in isotope and trace element geochemistry, we will then be able to tease out the climate signal recorded in the shells of the foraminifera.
The scientific objectives of ACCAI are unique as they will provide not only observation of modern Essential Climate Variables (ECV) but will allow us to look into the past to assess how ECV’s have evolved since before pre-industrial conditions. This long-term perspective is crucial in order to deconvolve natural variability of the climate system from anthropogenic climate change. Improving our understanding of how the atmosphere-ocean climate system communicate ECVs today and in the past will aid us to better understand our environment and the environmental consequences of human activities.
Project ACCAI brings together researchers from, the University of Southampton, National Oceanographic Centre (Southampton, UK) the Bjerknes Centre for Climate Research (Bergen University, Norway) and NUI Galway.
Funded through the
Constraining the Impact of Ocean Acidification on Arctic Foraminifera
Project: iCRAG 2
Dr Thomas Weiss & Dr Audrey Morley
In this project, we pioneer a conceptually unique dual approach to identify the distinct microstructural and geochemical processes of dissolution that alter the original signal of essential climate variables or ECVs (e.g., temperature, salinity, pH) recorded in Neogloboquadrina pachyderma (NP) shells. Specifically, we will combine novel techniques in microCT scanning and interpretative frameworks developed in biomedical engineering with traditional geochemical tracers of ECVs to statistically determine the signal contribution of explanatory variables (e.g., ECVs, dissolution, diagenesis) to geochemical response variables (e.g., Mg/Ca, δ11B, δ18O) using a predictive generalized linear model (GLM). Combining biogeochemical techniques and innovative microstructural analyses on NP will allow us to quantify physiochemical processes, that influence how geochemical tracers are recorded, at the time of proxy development. This approach will advance our understanding of Arctic climate and thereby provide the critical basis for testing future hypotheses, inside and outside of the Arctic, related to mechanisms controlling climate tipping points globally in the past, present, and future.
This project brings together researchers from, the University of Southampton, National Oceanographic Centre (Southampton, UK) the Bjerknes Centre for Climate Research (Bergen University, Norway) and NUI Galway and is funded by iCRAG the SFI Research Centre in Applied
The impact of early diagenetic processes in surface marine sediments on geochemical tracers recorded in planktonic foraminifera
Hridya Krishnakumar, PhD Candidate
Early diagenetic processes begin the moment PF touch the sediment. The physical evidence left behind by early diagenesis in the top-most sediments is expected to be less and not on the same scales as observed by net dissolution and overgrowth precipitation typically associated with deep-time diagenesis. Still, recent evidence suggests that early diagenesis may alter the SST signal of the Mg/Ca – temperature proxy by 2-3 °C. However, the impact of early dissolution, linked to organic matter degradation and stable mineral recrystallization (e.g., mineral-fluid exchange) in surface sediments specifically on high Mg phases in PF calcite are rarely considered or quantified.
To assess early diagenesis of PF at the sea floor, the analysis of pore water geochemistry will be paired with trace element, isotope, and microstructural analysis (microCT) on recently deposited NP from a large collection of multicores retrieved from different depositional environments (e.g., open ocean, slope, shelf). Specifically, the successful candidate will target the potential of short-term mineral-fluid exchanges within the top 30 cm of sediment, which exhibits sharp gradients in oxygen, microbial activity, pH, alkalinity, and biological activity for a diverse set of depositional environments. The impact of recrystallisation on geochemical tracers will be assessed via paired SEM-EDS elemental mapping and solution analysis of Mg, Sr, Mn, and δ13C. To test if early diagenetic processes are indeed a feature of distinct depositional environments and porewater chemistries, the successful candidate will also assess the presence of microstructural and geochemical diagenesis markers in the epibenthic foraminifera Cibicidoides wuellerstorfi. This will confirm whether observed markers are truly linked to depositional environments and their respective geochemistry. This PhD position will be supervised by Dr Audrey Morley (University of Galway).
The impact of physiological and ontogenetic processes on geochemical tracers recorded in planktonic foraminifera
The leading hypotheses describing the incorporation of Mg, B, O, and C species into calcium carbonate proposes that alongside seawater pH/carbonate ion and temperature, calcification and metabolic rates exert a control on the geochemical composition and isotopic fractionation in planktonic foraminifera (PF). Also, it is often assumed that PF migrate vertically in the water column during their life cycle. However, whether this is the case and how/if migration influences the geochemical tracer recorded in pristine calcite, and how it is subsequently represented in climate archives remains unknown. To address these gaps in knowledge it is therefore essential to determine the impact of both physiological and ontogenetic processes on geochemical tracers recorded in live PF.
To achieve these goals, the successful candidate will constrain PF respiration/metabolic rates on living specimen collected via plankton tows from Greenland, Irminger, and Labrador Seas to empirically constrain the hypothesised relationship between porosity and respiration for PF. Further, the candidate will determine calcification and growth rates of the same individuals using 3D volume reconstructions of test chambers using novel advances in microCT imaging to identify individual chamber thickness and volume during growth. The successful candidate will also constrain the hydrographic parameters of the calcification environment to identify the empirical relationships between geochemical tracers, essential climate variables, respiration, calcification, and growth rates. To assess vertical migration, live PF specimen will be collected and analysed from closely spaced tows (e.g., 20 m depth intervals). These will elucidate whether geochemical signals can be traced to distinct depth intervals and thereby constrain migration. This PhD position will be Co-supervised by Dr Audrey Morley (University of Galway) and Dr Julie Meilland (MARUM, Bremen University).
Reconstructing Oceanic Carbon Dioxide Uptake
in the Eastern North Atlantic during three interglacial
periods: A model-data comparison.
Marta Cabello, PhD Candidate
Although atmospheric carbon dioxide is one of the largest contributions to global warming, the vast majority of the global budget of carbon dioxide is stored in the deep ocean through North Atlantic Deep Water (NADW) formation, providing the oceans with the capacity to control the uptake of carbon dioxide. However, it remains uncertain how(if) the ocean is going to continue absorbing atmospheric carbon dioxide in a warming future, especially since current predictions do not take into account changing rates in oceanic carbon dioxide sequestration. This research aims to help disentangle this 40 years old dilemma by looking at how the Eastern North Atlantic contributed to regulate the exchange rate of carbon dioxide between the ocean and the atmosphere during previous interglacial periods. The information obtained will serve to improve current climatic models, which will allow policy makers to create more effective mitigation plans against the consequences of global warming.
Past Research Projects
Assessing High-Impact Climate Events During
Warmer than Present Environments
Michelle Curran, PhD
My research investigates the impact and variability of warmer than present environments for north-western Europe. The overall aim of this research is to assess the response of natural modes of climate variability: the Atlantic Multidecadal Oscillation (AMO) and the Atlantic Meridional Overturning Circulation (AMOC) during periods of enhanced warming in the Arctic. Targetingtwo interglacial periods of the past 500 thousand years, namely the Holocene (11.7 thousand years ago– present) and MIS 11 (~390– 440 thousand years ago), the reconstructions will enable us to identify baseline conditions during periods of enhanced warming of the climate system.
The AMO is a basin wide observation of sea surface temperatures in the North Atlantic Basinthat captures the complex processes involved in the coupled ocean-atmosphere system. It records the variability of atmospheric modes on multidecadal timescales (e.g. the North Atlantic Oscillation, the East Atlantic pattern and the Scandinavian Pattern) as well as subpolar gyre dynamics and circulation of North Atlantic water masses. The AMOC is a system of surface and deep water circulation in the Atlantic basin that links the ocean and the atmosphere. The surface water, North Atlantic Current (NAC) transfers warm, saline waters poleward. The North Atlantic Deep Water (NADW) transports cold, saline waters southwards at depth. This circulation is crucial to Europe’s climate. As the warm NAC reaches the mid-latitudes it releases heat and warms the atmosphere. Through this ocean-atmosphere heat flux the NAC aids in the maintenance of temperate climates of north-western Europe.
Using a multiproxy approach (sortable silt analysis, geochemical analysis (paired Mg/Ca - δ18O), X-ray fluorescenceanalysis, rare earth analysis and assemblage counts on both benthic and planktonic foraminifera) will facilitate the reconstruction of past changes in ocean-atmosphere climate dynamics. This will enable the inference of the impact of warmer than present environments on the AMO, the AMOC and thereby our climate in north-western Europe.This research is timely as it is unclear how Ireland’s climate will react within a warming world.
Providing Insights from Climate Archives: a Multiproxy
Approach for the Reconstruction of AMOC Response to
Quaternary Climate Events
Dakota Holmes, Msc
Our limited understanding of how the climate system is (will) responding to current (future) rates of anthropogenic
global warming is linked to insufficient data from past environmental responses to a changing climate. It has been hypothesised that enhanced high-latitude warming in response to global warming may lead to an abrupt slowdown of the Atlantic Meridional Overturning Circulation (AMOC); an important part of the climate system which plays a crucial role in oceanic northward heat transport that maintains a mild climate for the Northern Hemisphere, including Ireland. An abrupt slowdown of the AMOC has thus the potential to significantly impact our climate in Europe and beyond. However, to date there are no palaeoclimate or modelling studies that can confirm this hypothesis for warmer-than present environments. This gap has led to large uncertainties when estimating the variability of AMOC-related climate events in the future and illustrates that our understanding of the precise mechanisms linked the AMOC and climate in times of abrupt change remain limited. Here I propose to investigate abrupt events that occurred during transitions between warm-interglacial to cold-glacial conditions of the Quaternary during low ice volume conditions. A key methodological approach of the proposed work is to assess both the response of the surface and deep branches of the AMOC within the same samples that were taken from an exceptionally high-resolution climate archive (DSDP 610). This will allow me to constrain the temporal structure and elucidate mechanisms driving the AMOC during climate events. The proposed research and expected scientific discovery presented here will provide a comprehensive understanding of past environmental changes in connection to ocean circulation and climate variability, supporting improved forecasting abilities and scenario development when estimating the likelihood of an AMOC-related event occurring in the future.
Assessing the Response of the AMOC During Times of Abrupt Climate Change
Megan Murphy O'Connor, Msc
Due to the short time-series of our observations (~150 years) and lack of an abrupt climate event occurring during this time, the precise response of the Atlantic Meridional Overturning Circulation (AMOC) to abrupt changes in climate cannot yet be determined. This gap in knowledge has led to large uncertainties when estimating AMOC variability in the future (e.g. IPCC51) and to widespread complacency when addressing the threats of global climate change. The Climate Change Advisory Council (CCAC) of Ireland stresses that we need to focus our research efforts on understanding the potential risks high-impact events associated with the AMOC may have for Ireland.
The proposed project addresses these goals using an interdisciplinary research strategy that is central to palaeoceanographic research. The proposed methodologies combine isotope and trace metal geochemistry, palaeoecological techniques, with physical grain size analysis to reconstruct the response of the AMOC to abrupt climate change under various boundary.
Assessing Diagenesis in Arctic Foraminifera
Mimi McKenzie, MSc
Although geographically remote, the Arctic plays a large role in the thermal regulation of the Northern hemisphere. A better understanding of Artic environments is therefore vital to climate change research. Foraminifera are marine calcifying protist and constitute a significant portion of the fossil record due to their abundance and preservation in the ocean and marine archives. As a result, they are commonly used for reconstructing past environments. Several geochemical techniques such as the trace elemental and isotopic composition of foraminiferal calcite are established palaeoceanographic techniques to reconstruct past seawater properties (e.g. temperature, salinity, carbonate chemistry). However, the interpretation of these chemical proxies relies on the assumption that there is little to no modification of the geochemical composition within the biogenic calcite after calcification, deposition, and burial at the seafloor (e.g., early diagenesis).
For example, Mg/Ca - palaeothermometry is an established tool for the reconstruction of past SSTs. However, magnesium preferentially dissolves over calcite. Early processes of dissolution and remineralization can therefore potentially alter the Mg/Ca composition of foraminifera in marine archives. Using SEM-EDS elemental mapping and 2D high resolution image analysis of recently deposited foraminifera, this research investigates whether early diagenesis at the sea floor impacts the Mg/Ca signature recorded in planktonic foraminifera deposited in the Nordic seas.