The role of ice streams in the demise of the British-Irish Ice Sheet

Accurate projection of the future evolution of the Greenland and Antarctic ice sheets is a key challenge of glaciology and climate science. Ice sheet flow is dominated by ice streams; narrow corridors of fast flow bounded laterally by slower flowing ice, discharging the majority of ice from an ice sheet. These ice streams are particularly vulnerable to retreat, and their behaviour evolves along with the ice sheet as a whole. These interactions contribute to uncertainty in projections of ice sheet evolution. In part, this uncertainty can be addressed by examining the palaeo record, providing information on ice stream behaviour over thousands of years. \nThis thesis presents a series of simulations of the British-Irish Ice Sheet using the latest generation BISICLES ice sheet model. Model simulations are used to determine the role of ice streams in the demise of the British-Irish Ice Sheet. First, BISICLES is used to examine the dynamical processes that control the retreat of a major ice stream of the British-Irish Ice Sheet, and this demonstrates vulnerability of the ice stream to Marine Ice Sheet Instability. Then a new basal sliding scheme is implemented coupled with thermo-mechanics, and this successfully models the placement and spacing of the majority of British-Irish Ice Sheet ice streams. Finally, simulations of the deglaciation style of the North Sea demonstrate the significant influence of the Norwegian Channel Ice Stream. \nThrough these simulations, in combination with novel model-data comparison techniques, the considerable role of ice streams in the demise of the British-Irish Ice Sheet is shown. Ice stream evolution and interaction with other factors driving deglaciation needs to be adequately considered in the aim of projecting the future evolution of the Antarctic and Greenland ice sheets. Research such as presented here, modelling and reconstructing palaeo ice sheets, continues to advance this aim.