Britain's coasts are already being affected by climate change, according to a panel of experts convened by the Government to assess the likely impact of global warming. These changes are altering the number, variety and distributions of every kind of marine organism, from plankton and fish to top predators such as seabirds.
Sea temperatures have increased, storms and waves are becoming more damaging and sea levels are beginning to rise faster than at any time in the previous century, the report says.
"We are observing large changes in our marine environment that are driven in part by climate change and that are predicted to continue into the future," according to the panel's report published today.
"Mitigating and adapting to these changes will present significant challenges for decision-makers," says the Marine Climate Change Impacts Partnership, a coalition of experts from institutions ranging from Cambridge University to the Met Office's Hadley Centre.
Sea surface temperatures around Britain's coastline have been rising by between 0.2C and 0.6C per decade for the past 30 years and there is every sign that they will continue to rise, especially in the South-east.
Over the past 50 years, severe winds have become more commonplace and the height of waves has increased by about 2 per cent per year in the western and northern parts of British territorial waters, the report says.
Global sea levels rose by between 1mm and 2mm per year during the past century, with an acceleration to 3mm per year between 1993 and 2003.
"During the 21st century it is likely that global average sea level will rise by between 9cm [3.5in] and 88cm relative to 1990 but it will not be uniform around the world," the report says.
"The anticipated range of relative sea-level rise by the 2080s (relative to the 1961-1990 mean) is 20 to 80cm in south-west England and 0 to 60 cm in Scotland," it says.
Oceans around the world are becoming more acid as a result of the increased concentration of carbon dioxide being absorbed at the sea surface. Computer models suggest that the increased acidity of British coastal waters will surpass the maximum acidity of existing levels.
"The full impacts of acidification remain largely unknown but organisms such as corals, some plankton, shellfish and sea urchins are expected to become less able to produce calcareous parts, such as shells, by the middle of the century," the report says.
Climate change is already beginning to affect the variety and distribution of marine species - although it is not the only factor affecting coastal wildlife.
"Cold-water species of plankton, fish and intertidal invertebrates are retreating northwards around the UK and the ranges of southern species are expanding," the report says.
"Fishing pressure remains the principal cause of changes in the abundance of most fish species, but climate has probably also played a role in some cases.
"For example, the decline of prey species (particularly sandeels) has resulted in low breeding success of kittiwakes and other seabirds," the report says. "Warm-water commercial species such as sea bass, red mullet and tuna are becoming more commonplace in our seas."
Ian Pearson, the Climate Change minister, said that the findings underlined the fact that global warming is the biggest environmental threat the world faces.
"Our seas play a vital role in shaping and regulating our climate and have a tremendous bearing on our future wellbeing," Mr Pearson said. "Rising sea temperatures, ocean acidification and melting polar ice are not just predictions, they are happening now," he said.
The species affected
Plankton
Warmer-water plankton has moved further north by 600 miles, with a similar retreat of cold- water plankton.
Fish
Warm-water species such as tuna, stingrays and triggerfish have increased in the waters of southern Britain. Cold-water species have retracted north in some regions, such as the North Sea.
Marine Mammals
Experts suggest that they are no more vulnerable than other wildlife, but as top predators they will be affected by changes in the distribution of fish.
Seabirds
Climate change has been linked with the poor breeding success, reduced survival and population decline of the kittiwake. Warmer winters have probably affected its main source of food, sandeels. Sea-level rise may affect breeding sites for shoreline-nesting species such as terns.
Intertidal Species
Southern, warm water species on rocky shores have increased in abundance and range as temperatures have risen. The purple acorn barnacle, for example, has extended its range by 100 miles, while cold-water species such as the tortoiseshell limpet have decreased in numbers. Some new species are likely to become established, displacing existing organisms.
Comments