Cycles have been observed and detected on Earth for a long time, particularly those related to the Earth’s rotation and revolution around the Sun, and those of our satellite, the Moon. These cycles range from a few hours to seasonal scales and are primarily recorded in the external layers of our planet, such as the hydrosphere, atmosphere, and living systems, especially plants. More surprisingly, these short-period cycles have also been recorded within the Solid Earth in active geological systems such as faults and volcanoes. This has been confirmed through a variety of geophysical and geochemical measurements, suggesting that all of Earth’s layers are influenced by and respond to lunisolar gravitational forces, despite the mechanisms behind these interactions remaining elusive.

Cycles recorded on Earth extend far beyond short timescales, as evidenced by the alternation of sedimentary layers and the succession of glacial and interglacial eras spanning several millennia. These long-term cycles, known as Milankovitch cycles, reveal the intrinsic connection between astronomy and climate over vast periods. This connection is particularly intriguing and relevant, as it may represent a crucial piece of a more comprehensive puzzle involving not only the Sun and the Moon but also the other planets in our solar system, all of which impact Earth's and Sun dynamics and suggesting that the Milankovitch theory might apply to much wider time ranges. Detecting and studying these periodic signals and their impact on Earth’s processes provides insight into how external forces interact with processes on Earth and valuable information about the processes themselves.

This Research Topic aims to explore the impact of these external forces on Earth’s dynamics by gathering works that show the variability of cycles through their timescales, the processes and systems that record them, and their impact on our planet. In particular, this topic aims to address the following questions:

• What are the timescales of the different cycles recorded in the various layers of Earth?
• What are the cycles detected by the different data representing Earth's envelopes (atmosphere, oceans, solid Earth, and biosphere)?
• What do such influences reveal about the interactions between Earth’s envelopes and between external forces and Earth’s processes and systems?
• What is their impact on dynamic and unstable systems?
• What do these cycles reveal about dynamic systems?

In addition, this Research Topic aims to provide an overview of the records of external forces on Earth by collecting observational studies that capture cycles in different parameters associated with Earth’s various envelopes. This will thus contribute to elucidating the role of external forces in the dynamics of our planet.

We look forward to receiving studies that illustrate diverse methodological and technical approaches to acquiring data and/or extracting periodic signals. We encourage works that report and explore observations at specific time scales (from hourly to Milankovitch cycles, including seasonal variations) and spatial scales (local to global), as well as reviews or perspectives.

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When The Earth Records Cycles