According to a new study, more than a fifth of the worlds' cetaceans are facing potential extinction because of global warming. Five of the six species of porpoises which inhabit the world's oceans are under threat which include the harbour porpoise, the vaquita, the spectacled porpoise, Dall's porpoise and Burmeister's porpoise.

One of the cetacean species most at risk from the impact of climate change is the North Sea's population of white-beaked dolphins which have almost completely disappeared from the West Coast of Scotland and found only in the shallower waters of the northern North Atlantic. The study headed by Dr Colin MacLeod, a research fellow at Aberdeen University shows global warming is likely to affect stretches of sea where almost 90 per cent of the planet's cetaceans are found. Dr MacLeod said that while some species, such as the common dolphin and the striped dolphin, were likely to benefit from the warming of the seas by expanding their suitable habitat, almost half of all cetacean species would find their areas of suitable habitat shrinking as the temperatures of the world's oceans continue to increase by one degree every decade.Species whose habitat could expand however may face other problems. Moving into new areas could see cetaceans mixing with species they normally don't mix with, leading to them being exposed to new parasites and diseases to which they have little or no immunity.

Scientists predict that the current trend of warming waters around the UK will continue in the foreseeable future. If it does, it is likely that white-beaked dolphins will continue to disappear which could represent a serious threat for the species as a whole, as well as a loss of one of the UK's most distinctive dolphin species. The Atlantic white-sided dolphin, the northern bottlenose whale and the Sowerby's beaked whale could also disappear from waters around Britain's coast. Some polar species, such as the narwhal and the beluga, are already known to be at risk from climate change

Strandings of whales and dolphins around Scotland have been monitored since the 1940's and cold-water species, such as the white-beaked dolphin, are now stranding less frequently, while warm-water species are being recorded more frequently, including the striped dolphin, a warm-water species that had not been recorded in Scotland before 1988. These findings follow the pattern expected if the warming of the sea around the UK is responsible for these changes.

This latest research shows that climate change is not something that will only affect people living in far off corners of the world in the future, but is already affecting Scotland's marine wildlife.