Advaenced state estimats of the ocean and cryosphere: innovative new tools to better understand, predict, and prepare for sea level changes

Sea level rise (SLR) is one of the most serious adaptation challenges facing humanity today. SLR increases the frequency and severity of storm surges, coastal flooding, and erosion, thereby damaging critical infrastructure, hampering economic activity, and potentially displacing more than 100 million people globally who live in coastal communities. Under "business as usual" conditions, global flood costs could increase to over £10tn per year by 2100, under 86 cm of sea level rise. Despite its importance, projections of SLR over this century are very uncertain. The greatest single source of uncertainty in SLR projections comes from the West Antarctic Ice Sheet (WAIS), which has the potential to eventually raise sea levels by over three metres if it melts entirely. The WAIS is held back from flowing into the ocean and raising sea levels by large floating ice shelves that protrude from the Antarctic coastline, acting like dams. These crucial ice shelves are melting increasingly rapidly; in recent decades, the rate of ice loss from all Antarctic ice shelves has increased by more than a factor of twelve. The ice shelves are very dynamic systems that can respond quickly to changes in ocean circulation, e.g. increased intrusion of warm water under the ice shelves can melt them from underneath. The threat of rapidly rising seas in the near-to-medium term future highlights the need for improved understanding of how ocean currents deliver heat to the vulnerable undersides of Antarctic ice shelves. Thus far, progress in this area has been hampered by the challenges associated with extracting detailed heat budgets, ice shelf melt rates, and sensitivities from a limited set of observations.

In this Fellowship, I will use sensitivity analysis techniques (i.e. adjoint modelling) to establish a next-generation framework for ocean and ice shelf modelling that will make a step change in our ability to make robust and useful SLR projections. I will, for the first time, combine observations and realistic physical models in a hierarchical ocean-ice state estimation framework that will allow me to: (1) obtain spatially-varying, observationally-constrained estimates of melt rates and other hard-to-observe parameters at the ocean-ice interface; (2) quantify the sensitivities of heat content and melt rates at the ocean-ice interface to local and remote air-sea interactions and ocean circulation; (3) create spatially and temporally detailed heat budgets to track how heat is delivered from the open ocean to the ice shelves; and (4) optimise future observing campaigns by intelligently targeting key locations for new measurements. This ocean-ice state estimation framework will be applicable to any ocean-ice system on Earth, offering the potential to transform our ability to understand the present and future behavior of these key sea level regulators. As a result, global societies will be better informed and hence better able to respond to sea level rise, reducing risks to low-lying infrastructure, communities, and businesses.

As a result of this Fellowship, the scientific community will be able to make more accurate projections of sea level rise, with an improved understanding of the uncertainties associated with ocean circulation and ice shelf melting. With this new information, local and national governments with interests in low-lying coastal communities will ultimately be better able to respond to sea level rise, reducing risks to infrastructure, communities, and businesses.

Local coastal communities:
The research for this Fellowship deals with an improved understanding of ocean circulation and ice shelf melting, with direct relevance to global and regional sea level rise. This is of immense importance to local coastal communities and, therefore, I will be holding four small-group workshops with local coastal community groups (e.g. the Avonmouth Community Hub) to discuss sea level rise, climate change, and coastal resilience. These workshops will be spaced over years 2-4 of the Fellowship. To assist me in getting these ideas across, I will work with Dr Andy Heath to create two scientifically-informative animation videos to show the connections between ocean circulation, ice shelf melt, ice sheet stability, and both global and regional sea level rise.

Government and IPCC:
I will not only work at the grassroots level but will also provide briefings for Government Departments (e.g. DEFRA) and at a global level providing data to the World Climate Research Project to ensure that my work is incorporated into IPCC and ISMIP processes.

General public:
Enthusing and informing the next generation is important, and to this end I will use my role as STEM ambassador to provide talks and engaging, hands-on activities in various educational settings from primary to tertiary education. I will also continue to host the popular and well-received "Meet Your Friendly Neighbourhood Climate Scientists" panel discussions at venues such as the annual Cambridge Science Festival.