RAT’S probable extinction could be a hint of what’s to come, writes Ilona Amos
A major milestone has been reached with the news that climate change has claimed its first official mammalian victim – a small and fairly unremarkable-looking rat called the Bramble Cay melomys, which made its home on a small, low-lying island on the Great Barrier Reef.
Several hundred of the animals were counted on Bramble Cay in 1978, but rising tides and extreme weather events have caused 97 per cent of their habitat to disappear in the past 20 years. The creature was last sighted in 2009, but recent failed searches have prompted experts to say it is likely extinct. The loss of this little rodent may not in itself trigger a major calamity, but it’s certainly a sad day for the planet and a harbinger of things to come.
The UK hosts almost half of all Europe’s seabirds, with Scotland home to around 70 per cent of them. But recent surveys have been throwing up some worrying trends, with some of our most important species suffering massive losses in the past 15 years.
Kittiwake numbers on St Kilda have plummeted by almost 90 per cent since 1999, sparking fears that the species may die out. Fulmars, guillemots and razorbill colonies on the archipelago have also experienced significant declines, falling by more than 50 per cent.
Scientists have suggested a number of stressors could be to blame, including over-fishing, increasing plastic pollution and predation by other seabirds species. However, most agree that rising temperatures caused by climate change are a key factor.
The survival of many of our marine creatures and seabirds hinges on the abundance of sandeels in our waters. The small eel-like fish can make up a huge proportion of seabird diets during the breeding season, but there is evidence that they are becoming much scarcer and smaller at the time the birds need them most. This means birds often struggle to find enough food to raise chicks and many starve to death.
Sandeels also make up about two-thirds of the diet of harbour porpoises and minke whales, and nearly half of the diet of common and grey seals. Dwindling numbers are thought to be causing a knock-on effect in marine mammals.
Sealife is strongly influenced by ocean currents for providing nutrients. The north-east Atlantic plays a crucial role in global ocean circulation, at the pinch point where the North Atlantic Drift is replaced at depth by cold waters pouring out of the Arctic basin. For this reason our seas are some of the world’s most productive, sustaining a teeming broth of algae, invertebrates, fish, mammals and birds.
But warming is threatening this. A Cambridge University professor has predicted the Arctic could be free of sea ice this year for the first time in millennia, with current coverage 1.5 million square kilometres lower than average. According to experts, the sea surface temperature in the southern North Sea has risen by some 2°C in the last 20 years. This has a dramatic effect on when different species of plankton appear, and sends ripples up the food chain. Conservationists believe rising ocean temperatures could be driving sandeels further north or deeper, meaning seabirds are unable to reach them.
It’s welcome news that Scotland has reached its 2020 greenhouse gas emissions targets early, regardless of how and why, and that there will be a new, tougher goal put in place shortly. But we cannot afford to be complacent. Increased efforts to combat our impact on the planet and careful management of our seas and must remain top priorities going forward.