Tina Heger, Maud Bernard-Verdier, Arthur Gessler, Alex D. Greenwood, Hans-Peter Grossart, Monika Hilker, Silvia Keinath, Ingo Kowarik, Christoph Küffer, Elisabeth Marquard, Johannes Mueller, Stephanie Niemeier, Gabriela Onandia, Jana S. Petermann, Matthias C. Rillig, Mark-Oliver Rodel, Wolf-Christian Saul, Conrad Schittko, Klement Tockner, Jasmin Radha Joshi, Jonathan M. Jeschke

• Global change has complex eco-evolutionary consequences for organisms and ecosystems, but related concepts (e.g., novel ecosystems) do not cover their full range. Here we propose an umbrella concept of "ecological novelty" comprising (1) a site-specific and (2) an organism-centered, eco-evolutionary perspective. Under this umbrella, complementary options for studying and communicating effects of global change on organisms, ecosystems, and landscapes can be included in a toolbox. This allows researchers to address ecological novelty from different perspectives, e.g., by defining it based on (a) categorical or continuous measures, (b) reference conditions related to sites or organisms, and (c) types of human activities. We suggest striving for a descriptive, non-normative usage of the term "ecological novelty" in science. Normative evaluations and decisions about conservation policies or management are important, but require additional societal processes and engagement with multiple stakeholders.