Prof. dr. Appy Sluijs

“To bring the future into focus, we have to turn to the geological past.”

Research focus: Paleoceanography, Climate change, Ocean acidification, Reconstructing climate, Biogeology

Appy Sluijs is the Professor of Paleoceanography at the Earth Sciences Department and chair of the research group Marine Palynology and Paleoceanography, at Utrecht University.

Focus on climate changes in the geological past

His primary research interests include climate and ecological change in the geological past. He particularly focuses on reconstructing temperature, marine ecology, hydrology, biogeochemical cycles and sea level during periods that were characterized by rapidly increasing, or generally high concentrations of CO2 in the atmosphere. He does so by examining sediments once deposited on the seafloor. These analyses allow Sluijs to see how the climate varied in the past, why, and what kind of biological impact these variations had. This knowledge helps to increase our understanding of how the 'Earth System' reacts to changes such as those occurring right now. Together with students and colleagues, he combines micropaleontological and geochemical (both inorganic and organic) techniques to quantify and understand the functioning of planet Earth under ‘greenhouse’ conditions. The results provide the ultimate tool to test the performance of climate and biogeochemical models under such conditions.

Taking core samples of the ocean floor

To conduct this research, Sluijs and a large group of international scientists use large ships to extract core samples from the ocean floor through the International Ocean Discovery Program IODP. These samples consist of layers of sand, clay and fossils that have been deposited on the ocean floor over millions of years. 'We examine the core samples quite closely while still on board, but once we're back on land we study the samples in much greater detail and can draw conclusions about how the ocean changes over time.' Thanks to these core samples, Sluijs has discovered, among other things, that the greenhouse gas disaster that led to the extinction of many deep-sea species 55 million years ago was the result of a climate change chain reaction, much like that projected for our future.

Recent work: studying dinoflagellates for ocean acidification in the past

More recently, he has started to work on the biogeology of an important but understudied group of marine protists, dinoflagellates. The biogeochemistry of dinoflagellates and their fossil remains (dinocysts) is dependent on sea water CO2 concentrations and pH; a relation we aim to develop into a proxy to reconstruct marine carbon cycling and ocean acidification in the geological past.


Inaugural lecture date