Climate change: impacts on our vision for clean
and safe seas
Sea-level rise will lead to more coastal flooding with
impacts on coastal erosion, coastal habitats, built
structures and possible threats to human life. Links between
land and sea are also strongly expressed in contaminant
transport (nutrients and other pollutants), as their seaward transport will be highly dependent on future climate change
on land (e.g. drier summers with episodic downpours; a
greater number of more severe storms).
The bold text indicates new information for the
2007–2008 report.
Coastal
flooding
Defra; MOHC;
University of
Southampton |
- Increased flood risk, from both rivers and the sea, is
one of the most significant predicted impacts of climate
change in the UK.
- An increasing trend in extreme water levels has been
observed and is most likely to be a consequence of
the rise in average sea level.
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- Further rises in sea level over the next 100 years will tend to
increase the frequency of extreme high-water-level events.
- Future changes in storminess may alter the frequency
of extreme high-water-level events, but the precise
effects are uncertain and will depend on location.
|
Nutrient
enrichment
Cefas; FRS;
NOCS |
- Drier summers may be contributing to a decrease
in nutrient inputs in European seas.
- It is difficult to discriminate between the effects of human
inputs (e.g. agricultural run-off) and those that may be due
to climate change through rainfall and ocean transport.
|
- Drier summers may decrease nutrient inputs, although
sudden storms may deliver pulses with consequences
that are difficult to predict.
- More intense winter storms will raise concentrations of
nutrients at the ocean surface and may increase transfer
of nutrients into shelf seas.
- If summer stratification (reduced mixing) becomes
stronger, nutrient supply to surface waters will reduce
during the productive seasons.
|
Harmful
Algal
Blooms
(HABs)
Cefas; FRS; NUI
Galway; SAHFOS |
- Harmful Algal Blooms (HABs) – harmful due to the release
of toxins and sometimes by oxygen depletion – are now
thought to be driven largely by ocean climate forcing,
with nutrient enrichment only relevant to some cases.
- HABs have increased in some areas of the north-east Atlantic
over the past 50 years, as the seas around Great Britain and
Ireland 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.
|
- Rising temperatures and reduced mixing of the water column
(increased stratification) would favour many HAB-causing
species. Susceptible regions, such as the eastern
Irish Sea and some estuaries, are also thought to
be vulnerable to elevated nutrient concentrations.
- The direct effects of storms (decreasing stability, lower
light levels) and associated nutrient pulses are less
predictable and may favour some HAB species
over others.
|
Pollution
Cefas |
- Unknown. Pollutant monitoring is currently inadequate
for identifying climate change related 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.
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