Extreme environments in a world of new extremes

Abstract Extreme environments, whether defined by climate, soils, or disturbance, at landscape or micro‐scales, are prevalent across Earth's surface and have long served as crucibles for ecological and evolutionary insights. Many foundational theories were developed in deserts, cliffs, ultramafic soils, and other harsh systems. Yet, these environments are usually studied in siloed, discipline‐ or ecosystem‐specific contexts, rather than as part of a generalizable macroecological model. Here, we propose reframing extreme environments as a unifying framework for ecology, one that can explore the boundaries of ecological processes, detect the limits of functional trait strategies, and improve predictions of ecosystem responses to emerging global extremes. We also revisit key ecological concepts, including species coexistence, succession, spatial ecology, and functional trait theory, through the lens of extreme environments, and identify emerging research opportunities that arise when these systems are treated as central to, rather than siloed in, ecological theory. Rather than exceptions or outliers, these systems should be recognized as central to understanding the resilience, adaptability, and future trajectories of life on Earth.