Climate change, occurring at different temporal scales and driven by various forcing mechanisms and boundary conditions, has been a pervasive feature of Earth’s system history. Investigating past climate variability provides valuable insights into the overall functioning of the Earth’s climate system, the interactive dynamics linking its different components (atmosphere, hydrosphere, cryosphere, lithosphere, and biosphere), the role of internal and external forcings, and the background of natural variability. A deep understanding of these processes and variables, together with the long-term perspective offered by the geological record, is key to better comprehending current climate changes and reducing uncertainties in future climate projections.

Moreover, studying the past allows us to reconstruct the impacts of climate change on environments, processes, ecosystems, and natural resources—not only in terms of transmission patterns, expression, and environmental response gradients but also by shedding light on how boundary conditions influence the sensitivity and vulnerability of various environmental components. This knowledge facilitates the development of informed and effective mitigation and resilience strategies.

The study of past climates and environments primarily relies on proxy data obtained from natural archives in marine, terrestrial, and polar records across different temporal scales. These archives are analyzed through cross-disciplinary and multidisciplinary approaches, drawing on expertise and methodologies from geology, biology, chemistry, and atmospheric physics—both through direct examination of the records and by developing conceptual and numerical models. For more recent periods, the integration of archaeological, historical, and instrumental data is also crucial for understanding the bidirectional relationship between human activities and climatic and environmental variations.