Climate change: impacts on our vision for clean and safe seas

Future changes in the intensity and frequency of extreme events may alter the pattern of inputs of chemicals, nutrients and pathogens to the marine environment and increase the risk of coastal flooding. Other climate changes may impact upon the fate of chemicals, nutrients and pathogens; change exposure of humans to pathogen risk; and alter the distribution and susceptibility of marine species. This area remains largely unstudied because current monitoring programmes are not specifically designed to evaluate climate change impacts, as they are largely focussed on the status and trends of inputs and concentrations of contaminants in the environment.

	WHAT IS ALREADY HAPPENING	WHAT COULD HAPPEN	CONFIDENCE
Coastal flooding Find out more... Hadley Centre, Defra	No clear trend in extreme water levels has been observed, other than those associated with a rise in relative mean sea level.	Future extreme flood events may become more common due to local relative sea-level rise and increased storminess. Flood events with a 50-year return period might increase in height by more than 1m during the 21^st century at some locations.	LOW
Nutrient enrichment Find out more... NOCS, Cefas	Unknown. Nutrient availability is an important component of marine ecosystems but long-term nutrient observations are currently inadequate for identifying climate change impacts on nutrient enrichment.	The input of nutrients from the shore, the natural process of removing it and how nutrients circulate through the water column are all likely to be affected by climate change. More episodic river flows might cause short-term high-concentration pulses of nutrients to near-shore environments.	LOW
Harmful Algal Blooms (HABs) Find out more... SAHFOS	HABs have increased in some areas of the north-east Atlantic over the past 50 years, as the seas around the British Isles have become warmer, especially since the mid-1980s. There is regional variability within this trend and some places, such as the east coast of Britain, have experienced reduced incidences of HABs	Potential increase in HABs associated with heavy rainfall and with high river discharges. Reduced mixing of the water column (increased stratification) would favour many HAB-causing species.	MEDIUM
Pollution Find out more... Cefas	Unknown. Pollutant monitoring is currently inadequate for identifying climate change impacts.	Climate change may influence the release of pollutants currently locked in seabed sediments. Terrestrial inputs of storm water containing untreated sewage and other pollutants may increase.	LOW

WHAT IS ALREADY HAPPENING

WHAT COULD HAPPEN

CONFIDENCE

Coastal flooding

Find out more...

Hadley Centre, Defra

No clear trend in extreme water levels has been observed, other than those associated with a rise in relative mean sea level.

Future extreme flood events may become more common due to local relative sea-level rise and increased storminess.

Flood events with a 50-year return period might increase in height by more than 1m during the 21^st century at some locations.

LOW

Nutrient enrichment

Find out more...

NOCS, Cefas

Unknown. Nutrient availability is an important component of marine ecosystems but long-term nutrient observations are currently inadequate for identifying climate change impacts on nutrient enrichment.

The input of nutrients from the shore, the natural process of removing it and how nutrients circulate through the water column are all likely to be affected by climate change.

More episodic river flows might cause short-term high-concentration pulses of nutrients to near-shore environments.

LOW

Harmful Algal Blooms (HABs)

Find out more...

SAHFOS

HABs have increased in some areas of the north-east Atlantic over the past 50 years, as the seas around the British Isles have become warmer, especially since the mid-1980s.

There is regional variability within this trend and some places, such as the east coast of Britain, have experienced reduced incidences of HABs

Potential increase in HABs associated with heavy rainfall and with high river discharges.

Reduced mixing of the water column (increased stratification) would favour many HAB-causing species.

MEDIUM

Pollution

Find out more...

Cefas

Unknown. Pollutant monitoring is currently inadequate for identifying climate change impacts.

Climate change may influence the release of pollutants currently locked in seabed sediments.

Terrestrial inputs of storm water containing untreated sewage and other pollutants may increase.

LOW