Climate change effects on UK shelf sea’s connectivity and hydrographic properties

Climate change is expected to cause important changes in ocean physics, which will in turn have important effects on the marine ecosystems. The ReCICLE project (Resolving Climate Impacts on shelf and CoastaL seas Ecosystems) aims to identify and quantify the envelope of response to climate change of lower trophic level shelf-sea ecosystems and their functional interactions, in order to assess the vulnerability of ecosystem goods and services in the UK shelf seas. The central tool for this work is an ensemble of coupled hydrodynamic-biogeochemical ecosystem models NEMO-ERSEM Atlantic Margin Model configuration at 7 km horizontal resolution (AMM7), forced by different CIMP5 global climate change models to generate downscaled scenarios for future decades.

Changes in connectivity patterns are expected to affect coastal populations of marine organisms in shelf seas. Holt et al 2018 (GRL https://doi.org/10.1029/2018GL078878) showed the potential for radical reorganization of the North Sea circulation in earlier simulations. To assess this particular issue particle tracking experiments are carried out during two 10 year time slices, in the recent past (2000-2010) and in the future (2040-2050) in ensemble members of the ReCICLE AMM7 regional downscaling showing contrasting circulation patterns. Surface particles were uniformly seeded in the UK shelf seas every month and tracked for 30 days. The resulting particle trajectories are analysed with cluster analysis technics aiming to determine if persistent oceanographic boundaries re-arrange in the future climate scenarios. The ecological effects of circulation and water masses changes in the future ocean are discussed from a Lagrangian perspective.