Life is fascinating in its complexity. Biological processes span a wide range of scales from sub-second, microscopic, molecular and genetic processes through to millenial timescale interactions with the Earth System's carbon, nitrogen, and other biogeochemical cycles. These systems are characterised by networks of interacting processes and feedbacks that cause these systems to continuously respond, change, and adapt. My research focusses on trying to understand how increasing atmospheric CO2 affects plant growth across scales, from photosysnthesis within leaves, through longer term ecosystem scales and feedbacks, and how these responses scale and interact with the Earth System as a whole. I use computational models to address research questions in this area with the aim to advance our understanding of how models work at the process level, to connect modelling directly with experimental work and scientists, and to provide robust modelling frameworks that account for and provide confidence in our understanding and predictions.