Disputas - Master of Science Naima El Bani Altuna

Master of Science Naima El Bani Altuna will on September 17 at 15.15 publically defence her thesis for the PhD degree in Science.

Title of the thesis:

«Millennial-scale variability of Atlantic water inflow in the northern Nordic Seas and the northwestern Barents Sea - Relationship to abrupt climate oscillations, cryosphere and methane seepage from the seafloor»

Popular scientific abstract:

Climate change is increasing Arctic air-temperatures very fast – twice as fast the rest of the world’s temperature. This is also affecting the ocean at high latitudes, where powerful greenhouse gases are stored in the seafloor trapped in ice-like cages (known as gas hydrates), that can melt if the temperature of the ocean increases. To understand how the ocean and the climate are connected, in this thesis we looked back in time to periods of rapid climate change during the last ice age, when temperature increased at a similar rate as modern. For that purpose, we studied the evolution of warm Atlantic water entering the northern Nordic Seas and the western Barents Sea using the chemical composition of shells of benthic foraminifera (microscopic single-celled organisms living in the seafloor).

In the northern Nordic Seas, we have also reconstructed sea-ice variability. We found that during cold atmospheric periods the ocean was warm (up to 5°C) because meltwater released from icebergs, and a sea-ice “lid” formed by the cold temperatures trapped the heat beneath. Instead, during warm periods the seafloor remained cooler with similar temperatures to modern. Furthermore, our work shows that both the disappearance of the sea-ice “lid” and the decrease of oceanic temperatures happened at the same time during the cold periods, which suggest a strong connection between both parameters. In the Barents Sea we focused on investigating the effect of the inflow of warm Atlantic water on gas hydrates in the seafloor. The Atlantic water did indeed affect the stability of gas hydrates, enhancing the melting of these compounds and causing the release of gas from the seafloor to the water column.

This study has improved our understanding of how the past inflow of warmer Atlantic water connects to past abrupt climate changes. Additionally, it has shed light on the relationship between Atlantic water and the stability of gas hydrates.

The thesis is published and available in Munin.

 

Supervisors: 

  • Professor Tine L. Rasmussen, Department of Geosciences, UiT (main supervisor)
  • Researcher Mohamed Ezat, Department of Geosciences, UiT

Evalution Committee:

  • Professor Dr. Marit-Solveig Seidenkrantz, Department of Geoscience, Aarhus University, Denmark (1. opponent)
  • Senior Research Associate Dr. Anne Jennings, University of Colorado Boulder, USA (2. opponent)
  • Researcher Dr. Amando Putra Ersaid Lasabuda, Department of Geosciences, UiT (internal member and leader of the committee)

Leader of the public defence and opposition ex auditorio:

The leader of the public defence is Professor Anders Schomacker, Department of Geosciences at Faculty of Science and Technology. If you have any questions for the candidate during the public defence, please send an e-mail to anders.schomacker@uit.no. He will announce your questions during the defence.

Trial lecture:

Naima El Bani Altuna will hold her trial lecture on the announced topic for the PhD degree in Science on September 17 2021 at 13.15 in the same auditorium.

Title of the trial lecture:

«Gas hydrate seeps – their impact on climate and interaction with ocean temperatures through time»

Streaming:

The trial lecture and the public defence will be streamed from this link.

 

Audience:

UiT follows the national guidelines regarding infection control. A maximum of 31 people are allowed in the auditorium during the defence, as long as everybody keeps a distance of 1 meter at all times.

When: 17. September 2021 at 15.15–18.00
Where: Auditorium 1.022, Teknologibygget
Location / Campus: Digital
Target group: Employees, Students
Contact: Maren L. Andresen
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