Examining the glacial cycle phase space through data-integrated glacial systems modelling

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The past is our fuzzy window to the future. Through this window, tantalizing discrepancies point to cracks***in our understanding of the coupled ice, earth, and climate system. The last 130,000 year history of ice and***climate change offers major changes in the state of the climate system as well as examples of abrupt tipping***point behaviour.******The dynamical source of the variability of this system is still poorly understood. There are also perplexing***shortfalls in explaining inferred global mean sea level at Last Glacial Maximum (the problem of “missing***ice”) as well the source of an inferred 6-10 m higher sea level during the last (Eemian) interglacial, about***125,000 years ago.******Scientific assessments of potential climate change rely heavily on climate models. Though replication of***present-day climate is a challenging test for models, it is only a limited test since these models are already***tuned to fit the present. To answer questions related to potentially large changes in the climate system***(especially so-called tipping points), models are best tested against the past.******Critical to these tests is a confident inference of the past change in topography, ice cover, and associated***meltwater drainage into the ocean. The proposed research will significantly refine these inferences through***statistically robust integration of advanced computed models and large diverse sets of paleo data. This***will either resolve or further clarify the missing ice issue. The research program will also apply these***refined ice chronologies to direct examination of variability in the glacial ice and climate system with models***encompassing the climate, ice sheet, and earth components.******By deploying increasingly sophisticated models within this framework, we will test the extent to which***current models and understanding can replicate and explain past ice sheet evolution and instability events.***These tests will in turn facilitate the estimation of uncertainties concerning both future ice sheet evolution***and associated ice sheet interactions with the climate system, addressing a major gap in current climate***change assessments.