The loss of Arctic sea-ice is one of the most compelling manifestations of man-made climate change. Profound environmental change is already affecting Arctic inhabitants and ecosystems. Increasing scientific evidence, including many key papers by the PI, suggests the impacts of sea-ice loss will be felt way beyond the poles. Linkages between Arctic sea-ice loss and extreme mid-latitude weather have become an area of increasing scholarly enquiry and societal interest. Yet, significant knowledge gaps remain that demand urgent attention; in particular, the robustness of response to sea-ice loss - and its underpinning physical causes - across different climate models. The Polar Amplification Model Intercomparison Project (PA-MIP) will significantly advance the state-of-the-art in understanding and modelling the climate response to Arctic and Antarctic sea-ice loss. It will enable deeper understanding of the causes and global effects of past and future polar change, and the physical mechanisms involved. PA-MIP is a novel and unique collaboration of UK and international scientists. To promote fruitful collaboration and drive research excellence, this proposal supports two key activities: a secondment scheme and a synthesis workshop, both with direct benefit to NERC-funded science.