Interview: "Analysing sediment cores allows us to determine the extent to which current changes are unprecedented"

In this interview, iC3 PhD student Luke Simmons discusses his research on how Arctic fjords respond to cryosphere changes, the methodologies he employs, and his passion for outdoor activities.

Thank you for being here today, Luke. Can you tell us a bit about yourself and the focus of your research?

My name is Luke Simmons, I am a PhD student at iC3. I completed my master’s in geosciences at UiT, focusing on sedimentology and the reconstruction of marine environments using proxies like foraminifera.

My PhD now centers on marine ecosystem responses in Arctic fjords to changes in the cryosphere. Specifically, I’m comparing regions around Greenland to understand how ecosystems respond to different oceanographic and climatic forces as well as land-to-ocean exchanges. Fjords, being the interface between land and ocean, are the perfect natural laboratories for this.

How do you study these changes in fjords?

We analyze sediment cores, looking at both organic and inorganic proxies. For example, we examine total organic carbon (TOC), isotopic signatures like δ13C and δ15N and the elemental composition of the marine sediments using XRF. We also measure trace element ratios in the tests of foraminifera and will soon be measuring neodymium isotopes in a range of our samples. 

These proxies allow us to better understand land-to-ocean fluxes, oceanic variations and past ice sheet dynamics. They also give insight into processes such as glacial erosion during advance and retreat and how this impacts the marine ecosystems.

Picture: Luke Simmons cutting a sediment core in two. Credit: Emeric Babut du Marès.

Why is this research important now?

The Arctic is experiencing dramatic climatic and oceanographic changes. Our role is to contextualize these changes by looking at past warm periods, such as the Holocene Thermal Maximum or the Medieval Warm Period.

By studying these intervals, we can determine the extent to which current changes are unprecedented and use this knowledge to inform future climate models. It’s about connecting the past, present, and future.

Have you learned new methodologies during this first year of your PhD?

Coming from a sedimentology background, I’ve been diving into biogeochemical analyses. For instance, I’ve worked with ramped pyrolysis oxidation to study the lability of organic matter, which helps differentiate between younger marine carbon and older terrestrial carbon. I’ve also explored age-dating organic matter using accelerated mass spectrometry.

These are relatively new techniques for me, and they’ve been exciting to learn and apply.

What technologies or methodologies are you the most excited about in your field?

The creativity of reconstructing past environments is thrilling. One methodology I’m particularly excited to explore more is the application of neodymium isotopes within Arctic fjord sediments. 

Whilst they have been used to trace open ocean circulation patterns for some decades now, their application in Arctic fjord environment is still within its infancy.

Contributing towards developing and refining our current understanding of how these proxies behave feels like being at the forefront of research, especially in challenging environments like Greenland.

Have you faced any challenges in your research so far?

Of course, although every challenge presents an opportunity for reflection and a chance to learn. One example that I’m sure many researchers can relate to is instrument failure and time delays. It is frustrating, but it gives you time to go deeper into the theoretical side of procedures and to more learn about sample preparation and lab operations.

Challenges like these are common in science, but are easily faced with a tenacious outlook.

Was there a breakthrough moment or memorable experience during your first year?

Attending the "Fjords in a Changing Climate" workshop was a highlight. Researchers from 12 countries came together to discuss our current understanding and state of knowledge of fjord science, share methodologies, and identify knowledge gaps.

It was inspiring to see the passion in the community as we all contributed to a synthesis paper on fjord research. It reinforced the significance of all our individual research areas and how they all contribute in one way or another to the big picture.

What does an ideal day off look like to you?

It depends on the season. In summer, I’d start with a run with my dogs, followed by berry picking, hiking, or fishing—there’s nothing better than spending the day outdoors and coming home with fresh berries or a good catch.

In winter, I love splitboarding, skiing uphill, and snowboarding down. Being active outdoors, no matter the season, is what makes a grand day out for me.

Picture: Luke Simmons on Svalbard. Credit: Håvard Gjesdal.

What’s one thing you’re looking forward to in the next year?

Professionally, I’m excited about a research stay at Cambridge. It’s a fantastic opportunity to generate results that will shape the rest of my PhD. Personally, I’m looking forward to the ski season and the simple pleasures of life in Northern Norway.

Luke Simmons is an iC3 PhD student in at the Arctic University of Norway in Tromsø, the capital of the Arctic. To find out more about his work, please check out his list of publications, or contact him by email.