High Sea Temperatures Have Led To A Marine Heatwave 'Unheard Of' Off Coasts Of UK And Ireland: Report

The temperatures off the northeast coast of England and the west of Ireland have broken records for late spring and early summer. These are expected to remain high due to the emerging El Niño event.

Some parts of the North Sea are experiencing a "category four" marine heatwave, which is considered "extreme", according to the NOAA. There are certain areas off the coast of England which have reached temperatures up to five degrees Celsius above normal levels. 

Sea temperatures are several degrees above normal off the coasts of the United Kingdom and Ireland, resulting in a marine heatwave 'unheard of'. This heatwave poses a serious threat to species, according to scientists, The Guardian reported. The temperatures off the northeast coast of England and the west of Ireland have broken records for late spring and early summer. Data has shown that the North Sea, which is bordered by France, Belgium, Netherlands, Germany, Denmark, Sweden, Norway, and the United Kingdom; and the north Atlantic, which lies between North and South America on the west and Europe and Asia on the east, are experiencing higher temperatures. 

Global sea surface temperatures in April and May reached an all-time high for these months, a Guardian report said, citing data from the Met Office, the UK's national weather service. The Met Office database has been holding data since 1853. Since the temperatures are expected to remain high because of the emerging El Niño phenomenon, June is also set to reach record high levels. 

El Niño is the warm phase of the El Niño-La Niña climate pattern, also known as the El Niño-Southern Oscillation (ENSO), which is one of the most important climate phenomena on Earth due to its ability to change the global atmospheric circulation. This, in turn, influences temperature and precipitation across the globe. 

El Niño conditions developed this year by early June. The atmospheric response to warmer-than-average Pacific sea surface temperatures emerged in May, the National Oceanic and Atmospheric Administration (NOAA) said in a statement dated June 8, 2023. The NOAA expects El Niño to continue into winter, and there is a 56 per cent probability of El Niño becoming a strong event at its peak. There is an 84 per cent likelihood of at least a moderate event occurring due to El Niño.

North Sea experiencing a “category four” marine heatwave

Some parts of the North Sea are experiencing a "category four" marine heatwave, which is considered "extreme", according to the US National Oceanic and Atmospheric Administration (NOAA), the report said. There are certain areas off the coast of England which have reached temperatures up to five degrees Celsius above normal levels. 

Quoting Daniela Schmidt, a professor of earth sciences at the University of Bristol, the report said the extreme and unprecedented temperatures show the power of the combination of human-induced warming and a natural climate variability like El Niño. 

How marine heat waves affected wildlife in the past

Schmidt said that marine heat waves are found in warmer seas like the Mediterranean, but such anomalous temperatures in this part of the North Atlantic are "unheard of". 

Schmidt explained that heat stresses marine animals. Citing instances in other parts of the world, where ocean heatwave has resulted in several mass mortalities of marine plants and animals, she said these heat waves will continue to destroy Earth's ecosystems as long as emissions are not cut dramatically. However, this will go unnoticed because it is happening below the surface of the ocean. The mortalities of marine plants and animals have resulted in hundreds of millions of pounds of losses in fisheries income, carbon storage, cultural values and habitat loss. 

According to the report, Dr Dan Smale from the Marine Biological Association, who has been working on marine heatwaves for more than a decade, and was surprised by the temperatures, said he always thought marine heatwaves could never be ecologically impactful in the cool waters around the UK and Ireland, but this is unprecedented and possibly devastating. 

Smale said the current temperatures are way too high but not yet lethal for the majority of species. However, the temperatures are stressful for many species. There could be a mass mortality of kelp, seagrass, fish and oysters, if the high temperatures continue through summer, Smale said. 

Quoting Piers Foster, a professor of climate physics at the University of Leeds, the report said both Met Office and NOAA analyses of sea-surface temperature show temperatures are at their highest ever level, and the average sea-surface temperature breached 21 degrees Celsius for the first time in April. Unprecedented high rates of human-induced warming are driving these high temperatures, Foster said.

He also explained that the shift toward El Niño conditions is adding to the heat, and there is evidence that there is less Saharan dust over the ocean this year. Normally, Saharan dust reflects heat away from the ocean. 

Marine heat waves have been increasing

Citing a 2019 study, the report said that marine heat waves are increasing, and the number of heatwave days have tripled in the past couple of years.

In the 30 years to 2016, the number of heatwave days increased by more than 50 per cent, compared with 1925-54. At that time, scientists said that the heat destroyed large quantities of sea life, "like wildfires take out huge areas of forest", according to the report. 

Humanity will also be affected due to damage to these hotspots, because humans are dependent on the oceans for numerous resources.