Fenja Kroos is a Researcher at the Ecologic Institute in Berlin. Her work focuses on biodiversity, nature restoration and nature-based solutions, as well as marine and Arctic topics. She also contributes to the international climate negotiations, supporting the German delegation in negotiations under the UNFCCC, the Kyoto Protocol, and the Paris Agreement. Her work spans natural climate change adaptation, financing biodiversity, the EU Forest Strategy, the 3 Billion Trees Initiative, as well as marine and Arctic governance. Fenja Kroos works in English and German.

For the Ecologic Institute, Fenja Kroos is involved in a variety of projects that deal among other things with Arctic governance, policy, and knowledge transfer. This includes the "YESSS – Year-round EcoSystem Study on Svalbard: Seasonally resolving ecosystem functioning in a warming Arctic" project and the project "DynARC: A pluralistic approach to dynamic marine conservation in the Arctic". 

Moreover, Fenja Kroos was actively involved in a project to support EU Member States in implementing the Nature Restoration Law. For Germany, she is working on a project commissioned by the Federal Agency for Nature Conservation to support the national implementation of the nature restoration targets, particularly the planning of the national restoration plans. 

In the MEER:STARK project, she is researching cross-sectoral cooperation for resilient ecosystems and sustainable climate adaptation in the North and Baltic Seas. In addition, she was actively involved in the EU Mission for the Restoration of Oceans, Seas and Waters, a strategic initiative to conserve and restore marine and aquatic ecosystems across the EU. She is furthermore involved in the Marine SABRES project, which aims to apply social-ecological systems thinking and an ecosystem approach to develop targeted solutions to marine biodiversity loss. 

She also worked on a project to mainstream climate and environmental objectives in EU funding programmes in the post-2027 period, as well as on a feasibility study on carbon sequestration through area-based nature conservation measures, particularly through the integration of biodiversity-enhancing measures into land use and on nature-based solutions for municipalities. She also works on issues related to the polycrisis, with a focus on climate change, biodiversity loss, and pollution.