Research currents: Grad student wins prestigious Schlanger Ocean Drilling Fellowship
Halima Ibrahim to focus on the interaction of ocean currents and ice sheets during the Mid-Pleistocene Transition
The ocean has a long memory, written in water and preserved in sediments deep under the sea floor.
Understanding how ancient seas responded to conditions in the past is among our best guides for predicting future changes in the climate, explained Halima Ibrahim, a doctoral candidate in geological sciences who served as a shipboard sedimentologist during the International Ocean Discovery Program’s 2023 expedition off the coast of Iceland.
Recently, Ibrahim became the first graduate student to win the highly competitive Schlanger Ocean Drilling Fellowship to continue her research. Fellowship awards are $30,000 and span a full year.
Ibrahim earned her bachelor’s and master’s degrees in her native Nigeria, and then briefly explored a career as a project manager. After realizing her passion for geosciences and research, she came to to pursue her doctorate in geology, focusing on sedimentary processes, climate and past environmental change with Associate Professor Molly Patterson’s research group.
Her research focuses on the Mid-Pleistocene Transition (MPT), which occurred between 750,000 and 1.25 million years ago when the Earth’s ice age cycles shifted from 40,000 to 100,000-year rhythms. During this transition, ice sheets grew larger and more stable, and glacial cycles became longer and more intense, she explained.
“This period marks one of the most profound reorganizations of the Earth’s climate system, influencing ocean circulation, atmospheric CO₂, and global temperature patterns,” she said.
For the project, she is studying ocean sediment cores collected south of Iceland to reconstruct changes in North Atlantic Ocean currents and understand how the Atlantic Meridional Overturning Circulation (AMOC) behaved during the period in question. The AMOC essentially functions as the ocean’s “conveyor belt” and plays a key role in regulating global climate, Ibrahim explained.
Ibrahim studies ice-rafted debris — essentially, materials transported by floating ice — to gauge the condition of icebergs and uses stable isotope analyses to reconstruct changes in deep-water properties and ice dynamics. By looking at the size of silt grains in the core, she will also be able to draw conclusions about the strength of past ocean currents.
“Larger grains indicate stronger currents,” she said.
Studying how the ocean and ice sheets interacted in the past will help us understand how both may respond to ongoing climate change, she said.
Ibrahim first learned about the Schlanger Fellowship in October 2023, after participating in IODP Expedition 395, which collected the cores currently being used in her project. She decided to take another year to strengthen her proposal, which required her to develop a new research idea separate from her doctoral work and a robust methodology to test it.
“Participating in an ocean drilling expedition and now leading an independent Schlanger Fellowship project has been an incredible journey,” Ibrahim said. “It’s shown me how collaborative, global science can help us piece together Earth’s climate history and inspire the next generation of scientists to do the same.”
Ibrahim’s experience has put her in contact with scientists from all over the world, from joining them onboard during a two-month research expedition to continued engagement as she develops her own research projects, Patterson noted.
“It has to be one of the best on-the-job training opportunities for any PhD candidate,” Patterson said.