Coastal Flooding

NOC; Dundee University; EA; Marine Institute, Ireland

• Over the past century, natural variations in storm frequency and magnitude over 10-20 year cycles have been the most important climatic factor driving coastal flood risk. However, changes in land use and movement of people and key services to coastal areas over this time period has generally increased vulnerability to coastal flooding.

• Coastal flood events in the future are far more likely to be exacerbated by rising sea levels than by changes to waves or storm surges.
• It has been estimated that a 40cm sea-level rise, which is broadly in line with UKCP09 projections by 2100 under a medium emissions scenario, would increase the number of properties at risk in eastern England from around 270,000 to 400,000.

Nutrient Enrichment

Strathclyde University

• Changes have occurred in nutrient concentrations in UK waters but it is not possible, at present, to distinguish between the relative contributions of climate, and other natural and anthropogenic factors, in driving these changes.

• Modelling studies suggest nutrient concentrations in the sea may decline if summers become drier. Large uncertainty remains in such predictions given the difficulties in confidently predicting the driving conditions (e.g. rainfall; changes to local ocean currents) and what may happen to anthropogenic inputs.

Harmful Algal Blooms (HABs)

Marine Scotland; Cefas; AFBINI; Marine Institute, Ireland; NUI, Galway; SAHFOS; SAMS

• The distribution of selected HAB species in the north-east Atlantic has changed over the last four decades.
• In Scottish waters the incidence of PSP (paralytic shellfish poisoning) toxicity of blue mussels (Mytilus edulis), primarily associated with the dinoflagellate genus Alexandrium, appears to have decreased since the turn of the century.

• An increase in tendency for stratification of the water column could influence the development of selected offshore blooms, some of which e.g. Karenia mikimotoi, have been associated with fish kills and benthic mortalities in coastal waters in south-western England, western Scotland, Orkney and Shetland.
• Climate change may influence the toxicity of some HAB populations as a result of any changes to species diversity, nutrient availability, temperature and irradiance (cloud cover).
• Increases in sea temperature could increase the geographic range of species that are not currently observed in UK waters. One candidate is Gymnodinium catenatum, a dinoflagellate associated with PSP events.

Pollution

Cefas; EA; Leeds University; Marine Scotland; University of Wales, Aberystwyth

• The current state of knowledge specifically on the impacts of climate change on marine pollution is limited and the knowledge gaps are numerous and extensive.

• Drought conditions will result in reduced dilution of chemicals whilst any increase in high rainfall events over land would increase runoff via sewers.
• Any increase in the frequency of storm events and storm intensity would impact on pollution loading through increased volumes of sewage overflow discharges and riverine microbial fluxes, making compliance with the aims of the Shellfish Waters Directive and the Bathing Water Directive difficult.

Human Health Impacts (marine vibrios)

Cefas

• Marine vibrios are an important group of pathogens with human health implications, linked to increasing seawater temperature and reduced salinity. They can cause seafood associated gastro-enteric or septicaemia illness that may occasionally be fatal.
• Infections are uncommon in the UK, and almost always related to overseas travel. However, reports of disease caused by marine vibrios have increased in some parts of Europe over recent years, and have tended to follow periods of unusually warm weather.

• Marine vibrio infections are predicted to occur as sea surface temperatures around the UK rise, possibly exacerbated by declining salinity as a result of localised intense rainfall events. The impacts maybe further increased by expansion in ranges of zooplankton that are important vectors for these species.