Climate change scenarios (Hulme et al., 2002) indicate annual average temperature increases of 2 and 3.5°C by the 2080s; wetter winters (winter daily precipitation up to 20% heavier), and drier summers with the largest relative changes in the south and east where summer precipitation may decline by up to 50%.  Sea levels are also expected to rise around the UK – between 26 and 86 cm by 2080s.

Although pollution monitoring is currently inadequate for identifying climate change related impacts there are many potential impacts that climate change could have on the UK marine environment. Changes to rainfall patterns may result in changes to the movement and distribution of chemicals e.g. increased leaching of pesticides applied to agricultural land during certain periods of the year.  Increased storm events during the winter will increase storm water flows in rivers and potentially inputs of untreated sewage effluent.  Decreased river flows in the summer particularly in the South of England will result in higher relative contributions of treated sewage effluent.  The biological oxygen demand will increase because of the increase in organic matter from treated sewage as well as any rise in temperature, which will increase bacterial respiration.  Heavy storm events during summer periods are likely to result in flushing of untreated sewage effluent and diffuse pollutants from surface runoff in storm overflows. The release of sediment-associated contaminants present on the seabed may also be changed by increases in temperature, changes in salinity regimes and increased storm events.

Increased risk of flooding because of climate change has implications for the inundation of land that is contaminated.  There may therefore be a greater risk of contaminants being remobilised in floodwater and of contaminated

sediment and water reaching the freshwater and marine environment.  The location of coastal industries e.g. power generation will need to take account of the increased risk of flooding in some coastal areas. With the increased development of ports and coastal areas handling of historically contaminated sediments is also an issue of increasing concern and its redistribution in the environment will be influenced by storm events.

The use and fate in the marine environment of specific chemicals may also be influenced by climate change because of changes in farming practice (e.g. increased use of some pesticides) and consumer choice (e.g. increased use of UV sunscreens and fate and effects in the aquatic environment (Buser et al., 2006))

• Download PDF (195 KB)

Low for both ‘what is already happening’ and ‘what could happen in the future’

Much monitoring effort has focussed on selected chemicals identified as of priority concern (e.g. metals such as mercury and organics such as hexachlorocyclohexane).  In many cases, the concentration of these chemicals has declined with the introduction of tighter discharge consents and the improvement of sewage effluent treatment.  With a few exceptions (e.g. in relation to sewage sludge disposal sites (Rees et al. 2006), Tributyltin (Rees et al. 2001) and steroidal chemicals), where contaminant-related biological effects are well characterised, changes in chemical concentrations have not been linked to changes in biological effects.  Links between chemical concentrations, biological effects and climate change factors are not yet developed in the literature and where time series datasets do exist confidence in showing these links is low.

See confidence section.

See full review.

Dave Sheahan
Centre for Environment, Fisheries and Aquaculture Science (Cefas), Pakefield, Lowestoft, Suffollk, NR33 0HT