Steffen uses Holocene and Pleistocene lake, wetland and fluvial sediments to reconstruct landscape and climate change in alpine and arid regions. His research is focused on Central Asia, the Near East and northwestern Africa, and Iceland. He is interested in the environments of early hominins and examines early human impacts on the landscape and aquatic ecosystems. Thus, a lot of his work is conducted in close cooperation with archaeologists. His specific expertise is the use of ostracod (micro-crustacean) species assemblages for palaeoecological inferences and geochemical analyses of ostracod valves for palaeoenvironmental reconstructions.
In Iceland, Steffen works on the distribution of shallow marine ostracods as indicators of ecosystem state and potential tools to monitor impacts of global climate change. His PhD students use insect remains such as chironomid head capsules to investigate human impacts on lake ecosystems in the last ca. 200 years, and work on the concentrations, types and sources of microplastics in lakes in Iceland.
