I aim to understand Earth’s large-scale properties that govern plate tectonics, the process behind mountain building, earthquakes, volcanism, and setting Earth’s long-term surface environment. To do this, I study processes across wide timescales, from earth tides (~hr) to ice-age rebound (~10,000 y), developing a rigorous theoretical understanding of these dissipative processes across this broad spectrum. I have established a new theoretical framework that allows self-consistent interpretation of observations across the broadest timescale range to coherently infer Earth’s fundamental properties, from deep mantle buoyancy to the transient nature of Earth’s mechanical properties. Armed with this deeper understanding, I apply these ideas to the wider Earth system by considering how such mantle dynamics feeds back into the climate system through coupling to ice sheets – once more, over a broad range of timescales from ice-age cycles (~100,000 y) to anthropogenically induced ice melt (~y).