The atmosphere of the early Earth was very different from that we find about us today. It was both hotter and contained a very different mix of chemicals. To understand the processes that shaped the current atmosphere and climate of the Earth, it is important to understand how the molecules in the primordial atmosphere absorbed and emitted light over a whole range of wavelengths (from infrared to ultraviolet). Interestingly a new discovered class of extra-solar planets (exoplanets) known as super Earths appear to have atmospheres similar to that believed to be present in the early Earth, raising the possibility that such atmospheres can be directly studied. Studying these exoplanets or modelling the early Earth requires significant quantities of laboratory spectroscopic data characterising the radiative processes involved for each molecule as a function of temperature. The ExoMol project was founded to provide exactly this sort of information which is provided by quantum mechanical calculations on a molecule-by-molecule basis. The proposed project will involve the calculation of line lists for key early Earth molecules and testing these against available laboratory measurements. The resulting data will be passed to modellers.