Volcano-climate interactions: reframing the volcano-climate puzzle.

Explosive volcanic eruptions are major natural perturbations of the Earth system. By increasing stratospheric aerosol loading, they exert a dual radiative forcing: enhanced scattering of incoming solar radiation induces global surface cooling, while absorption of terrestrial radiation warms the lower stratosphere. Together, these radiative perturbations trigger complex dynamical responses within the coupled ocean-atmosphere-sea ice system, leading to diverse regional impacts. The resulting climate impacts are strongly event-specific, depending not only on the eruption's magnitude, location, and timing, but also on the prevailing climate state and the phase of intrinsic variability. In this Perspective, we use the early nineteenth-century volcanic cluster-dominated by the unidentified 1809 eruption and the 1815 Mount Tambora eruption-as a natural test case to assess recent progress in volcano-climate research. We review and reassess advances in volcanic source characterization, aerosol forcing, climate response, and attribution, using new analyses of this volcanic cluster to illustrate how uncertainties propagate across these interconnected components. Taken together, recent advances indicate that volcanic climate impacts cannot be understood as deterministic responses to forcing alone, but emerge from the interplay between forcing characteristics, internal variability, and state-dependent feedbacks. We identify key remaining bottlenecks and outline future research directions, emphasizing the role of high-resolution modeling, data assimilation, AI-based methods and emulators, and probabilistic frameworks to drive further progress. Finally, we argue that addressing the volcano-climate puzzle will require coordinated engagement across the geoscience community to better constrain volcano-climate interactions, with the long-term goal of fully integrating volcanic forcing into Earth system science. Graphical abstract: