Rates of relative sea-level rise during the final stage of the last deglaciation, the early Holocene, are key to understanding future ice melt and sea-level change under a warming climate¹. Data about these rates are scarce², and this limits insight into the relative contributions of the North American and Antarctic ice sheets to global sea-level rise during the early Holocene. Here we present an early Holocene sea-level curve based on 88 sea-level data points (13.7–6.2 thousand years ago (ka)) from the North Sea (Doggerland^3,4). After removing the pattern of regional glacial isostatic adjustment caused by the melting of the Eurasian Ice Sheet, the residual sea-level signal highlights two phases of accelerated sea-level rise. Meltwater sourced from the North American and Antarctic ice sheets drove these two phases, peaking around 10.3 ka and 8.3 ka with rates between 8 mm yr⁻¹ and 9 mm yr⁻¹. Our results also show that global mean sea-level rise between 11 ka and 3 ka amounted to 37.7 m (2σ range, 29.3–42.2 m), reconciling the mismatch that existed between estimates of global mean sea-level rise based on ice-sheet reconstructions and previously limited early Holocene sea-level data. With its broad spatiotemporal coverage, the North Sea dataset provides critical constraints on the patterns and rates of the late-stage deglaciation of the North American and Antarctic ice sheets, improving our understanding of the Earth-system response to climate change.

The long-term sediment demand of the Dutch coast is integral to the current Dutch Coastal Flood and Erosion Risk Management policy. The Coastal Genesis 2 research programme was initiated to address the sustainability of this policy under sea level rise by focusing on key uncertainties in the conceptual model of the sediment demand of the Dutch coast. The substantive scientific contributions of the Coastal Genesis 2 research programme are analysed in this paper by applying an output-outcome-impact framework. The direct outputs of the programme are categorised in terms of the knowledge types of a 5-element framework, namely measurement data, simulation models, system understanding, conceptual models, and policy and practice. The research outcomes arise from the interactions of these knowledge types. Our analysis of these outcomes highlights that synthesising new scientific insights into shared conceptual models is critical to achieving impact in policy and practice. In the Dutch situation, a new shared conceptual model of the long-term sediment demand enabled the development of four potential nourishment strategies aiming to meet the strategic goals of the Coastal Flood and Erosion Risk Management policy on a timescale up to 20 years. In 2021, the Minister of Infrastructure and Water Management officially articulated her intention to adopt the advised nourishment strategy from 2024 onwards. This represents a lasting impact of the Coastal Genesis 2 research programme in policy and practice. Further, the insight regarding the pivotal role of shared conceptual models as intermediary between science, policy and practice may prove useful in the design of future research programmes aiming to influence policy.