This project was focussed on exploring the contributions of different sources of uncertainty in global reconstructions of surface temperature, especially those associated with the spatial infilling. The project was undertaken by Maryam Ilyas during her doctoral research at University College London. The title of her PhD thesis was "Sparse, fitted empirical orthogonal functions for climate reconstruction". It was supervised by Serge Guillas and Chris Brierley. Funding for the research visit to Doug Nychka, during which the particular innovations present in this dataset were developed, was provided by the ReCOVER project (EP/M008495/1)