JERSEY’S sea temperature is about 1°C above average – but the waters have so far avoided an extreme marine heatwave that has hit many parts of the UK and Ireland.
Some areas are in the grips of the most intense marine warming on Earth, with water temperatures up to 4°C above the seasonal norm, according to analysis by the UK Met Office and the European Space Agency.
The data shows that sea water around almost the entire coastline of the British Isles is warmer than usual, with the most-affected areas being the east coast of England and Scotland, and off north-west Ireland.
The marine heatwave has been classified as category four, meaning ‘extreme’, by the US National Oceanic and Atmospheric Administration.
It is believed that the warming has been caused by a combination of human-induced climate change pushing up the temperature baseline, and the added effect of the current spell of hot weather.
Many areas of the English Channel have so far escaped the marine heatwave, although sea temperatures are generally higher than average.
Jersey’s sea temperature remained above average everyday last year except for a short period during December, and is currently at 15.9°C.
Diver Kevin McIlwee, from Jersey Marine Conservation, said several species have been affected by rising sea temperatures over recent years. The leather sea squirt – an invasive species – is being seen in far greater numbers than before. Juvenile fish are also being spotted in abundance far earlier in the breeding season. Meanwhile, sea hares – a marine snail often found in shallow water – appear to have recently decreased in numbers.
Scientists have warned that the sudden rise in water temperatures could have a catastrophic effect on marine life in the worst-affected areas of the British Isles.
Professor Yueng-Djern Lenn, an oceanographer at Bangor University, said: ‘There is no escape from the heat for sea creatures, they can’t turn on the air conditioners, and this can exert heat stress on their bodies, which can lead to death.
‘We don’t know yet how long this UK event will last, but we would expect our marine ecosystems to not escape unscathed.
‘If there isn’t enough of a break between such events, allowing the ecosystems time to recover, the only winners will be the open ocean swimmers in the short-term.’
