Jorijntje Henderiks, professor i paleobiology

Could you briefly explain the research that you do?

We study the fossil remains of marine calcifying phytoplankton, specifically the coccolithophores that produce minute platelets of calcite (called coccoliths

How did you get interested in this?

Already in high school I had a very broad interest in the natural sciences—and traveling the world! During those years I learned more about geology from a dear family friend, who talked enthusiastically about his research that bridged the fields of geology and biology. The fact that most carbonate rocks on Earth are actually formed by organisms is a great example of the link between these subjects. This I found fascinating, and it still motivates my research questions and teaching activities to this day.

What has your research helped us understand?

- My research has largely focused on the size variation within coccolithophores over geologic history. A macroevolutionary size decrease in coccolithophores has likely weakened the power of the so-called “carbonate pump”, which is a biogeochemical mechanism by which atmospheric CO2 is locked into carbonate rocks and stored for millions of years at the ocean floor. Overall, coccolithophores were more heavily calcified and globally more prominent in the past, before ca. 34 million years ago, when global climate shifted from a “greenhouse” to an “icehouse” world. Together with a colleague from Yale, we were the first to show a relationship between the long-term evolution of atmospheric CO2 content (reconstructed with organic geochemistry) and coccolithophore cell size (which is estimated from fossil coccolith size). Our records reveal an overall decrease in coccolith size as CO2 levels decreased over the past ca. 50 million years. This is a very intriguing pattern that we are investigating in more detail.

What would you like to research in the future?

- For the known future, I am excited to be invited on an International Ocean Discovery Program (IODP) expedition in the summer of 2015. As part of an international team, we will drill into marine carbonate sediments offshore NW Australia to study the last 5 million years of Earth’s history. The sampling will give me an opportunity to study coccolithophore evolution and climate change during the time period when small, blooming species had become dominant – very similar to today.