What role does environmental change play in Jakob von Uexküll’s thought? And what role can it play in a up-to-date Uexküllian framework? Admittedly, in hindsight it appears that the Umwelt theory suffers from its reliance on Uexküll’s false premise that the environment (including its mixture of species) is generally stable. In this article, the Umwelt theory of Uexküll is reviewed in light of modern findings related to environmental change, especially from macroevolution. Uexküll’s thought is interpreted as a distinctive theory of (...) phenomenology—an ‘Uexküllian phenomenology’—characterized by an assumption of the (in the realm of life) universal existence of a genuine first person perspective, i.e., of experienced worlds. It is suggested that acknowledging this distinctiveness is critical for eco-phenomenology as well as for biosemiotics; the latter of which can only thus thrive as a true ‘semiotics of being’, rather than a mere ‘semiotics of functioning’. (shrink)