Latest news with #oceantemperatures
Yahoo
3 days ago
- Science
- Yahoo
Marine heatwaves may have driven the world's oceans to a critical tipping point, scientists warn
In 2023, the Earth experienced an unprecedented surge in marine heatwaves across its oceans. They set new records in intensity, geographic extent, and duration, with many lasting well over a year and 96 per cent of the ocean surface affected. Following new research, scientists now warn that these prolonged temperature spikes might herald a tipping point for the world's oceans with grave consequences for the planet. Earth's oceans may have undergone a fundamental shift In 2023, heatwaves resulted in both the North Atlantic and Southwest Pacific oceans experiencing record-breaking sea surface temperatures. 'We know that marine heatwaves have become increasingly common and more intense over time because of global warming. We also know that the El Niño that kicked off in 2023 allowed more heat to enter the ocean,' says climate research scientist Alex Sen Gupta from the University of New South Wales. 'But these factors alone can't explain the incredible scale of the jump that began in 2023.' Scientists from China, the USA and Thailand decided to investigate what was behind the extreme warming and what ramifications it has and could have in the future. Related Heatwaves in Europe: Which countries face the biggest GDP and labour productivity losses? Sea temperature in Portugal's Algarve reaches record highs as 'marine heatwave' hits The research found that reduced cloud cover, which allows more solar radiation to reach the water, was a key driver, alongside weaker winds that diminish cooling from evaporation, and changing ocean currents. While the paper doesn't explain why these influences coincided to smash temperature records, it highlights why it is critical to dedicate more research to the mechanics of ocean warming. The study voices scientists' fears that the Earth's oceans have undergone a fundamental shift, transitioning to a new, hotter state that they say is now the 'new normal'. Author Zhenzhong Zeng, from the Southern University of Science and Technology in China, said figures suggest heat in the world's oceans is accumulating exponentially. If this is indeed the case, it is a trend that would go against what current climate models have projected. Ocean warming has devastating effects on marine ecosystems and life on land The study also warns that the oceans' shift to a permanently warmer state could have devastating effects for life on Earth. This is because they play a central role in regulating global temperatures by storing and slowly releasing large amounts of heat. Because the oceans take more time to react to changes than the atmosphere, the effects of heatwaves can be both delayed and dramatic. This includes hampering the ability to predict short-term extreme weather events, such as hurricanes, and longer-term climatic changes. Related How your old phone could become a 'tiny data centre' helping researchers to track marine life Lost income, less tourists and freak weather: Overheated seas affect far more than just marine life Prolonged increased water temperatures would also be catastrophic for marine ecosystems, triggering mass die-offs or migrations of species. It also increases the chances of coral reef collapse - a concern not least because the loss of coral hinders the ocean's ability to sequester carbon, leading to more heating. On land, it would mean accelerated warming, as sea breezes carry hot air inland. This can cause more intense and widespread droughts, heatwaves, wildfires and storms. This was already evidenced by Storm Daniel in 2023, which killed nearly 6,000 people. Attribution studies found that it was made 50 times more likely and 50 per cent more intense by high sea surface temperatures in the Mediterranean. Are marine heatwaves becoming the new normal? The findings are particularly worrying given the subsequent heatwaves in 2024 and 2025 that boiled oceans around the world. This year, sea surface temperatures in the Mediterranean reached their highest level ever recorded for June. On 29 June, sea surface temperatures hit 26.01°C, according to data collected by Copernicus and analysed by Météo-France. Overall temperatures were 3-4°C higher than average. It sparked fresh warnings from marine scientists of the devastating impacts on biodiversity, fisheries, aquaculture, and weather patterns across southern Europe and North Africa. Related Climate change tripled death toll of latest European heatwave, first ever rapid study finds Heatwaves, floods and sea level rise: UK weather extremes are increasing, Met Office confirms In May, a marine heatwave hit the UK, a place where surges in sea surface temperatures are still a relatively new phenomenon. Parts of the North Sea, English Channel and Irish coast were as much as 4°C warmer than average. Scientists say an exceptionally warm, dry spring coupled with weak winds allowed heat to build on the ocean's surface. They warned the flare-up could disrupt marine ecosystems, altering breeding cycles, enabling blooms of harmful algae or attracting jellyfish that thrive in warmer waters. 'It is critical that we continue to measure, monitor and model the future of our Earth' A fundamental shift in ocean dynamics that defies current climate models is an alarming prospect. Some researchers have responded that the warning is premature. 'We don't know what's going to happen next year, and it [ocean temperatures] might just come back to something that's much more, let's say, normal,' Neil Holbrook, climate scientist at the University of Tasmania in Australia, told the New Scientist, adding that current research can only draw on a few years of data. But even so, scientists back the paper's exhortation to study the drivers of ocean warming. 'While we urgently need to reduce our GHG emissions, it is critical that we also continue to measure, monitor and model what our future Earth is going to be like,' says Jaci Brown, Climate Lead at Australia's Commonwealth Scientific and Industrial Research Organisation (CSIRO). 'If we don't, we can't prepare, and we are walking into the unknown with dire consequences for our future food, health and security.'
BBC News
12-07-2025
- Climate
- BBC News
Intense Mediterranean Sea heatwave raises fears for marine life
Warmer water at the seaside might sound nice for your holiday dip, but recent ocean heat in the Mediterranean Sea has been so intense that scientists fear potentially devastating consequences for marine temperature of the sea surface regularly passed 30C off the coast of Majorca and elsewhere in late June and early July, in places six or seven degrees above probably warmer than your local leisure centre swimming has been the western Med's most extreme marine heatwave ever recorded for the time of year, affecting large areas of the sea for weeks on end. The heat appears to be cooling off, but some species simply struggle to cope with such prolonged and intense warmth, with potential knock-on effects for fish give you some idea of these temperatures, most leisure centre swimming pools are heated to roughly 28C. Competitive swimming pools are slightly cooler at 25-28C, World Aquatics pools are a bit warmer, recommended at 29-31C or 30-32C for babies, according to the Swimming Teachers' balmy temperatures might sound attractive, but they can pose hidden threats. Harmful bacteria and algae can often spread more easily in warmer seawater, which isn't treated with cleaning chemicals like your local pool. Sea temperatures of 30C or above are not unprecedented in the Med in late they are highly unusual for June, according to data from the European Copernicus climate service, Mercator Ocean International, and measurements at Spanish ports."What is different this year is that 30C sea temperatures have arrived much earlier, and that means that we can expect the summer to be more intense and longer," said Marta Marcos, associate professor at the University of the Balearic Islands in Spain."I grew up here, so we are used to heatwaves, but this has become more and more common and intense." "We're all very, very surprised at the magnitude of this heatwave," added Aida Alvera-Azcárate, an oceanographer at the University of Liege in Belgium."It's a matter of high concern, but this is something we can expect to be happening again in the future." Marine heatwaves are becoming more intense and longer-lasting as humanity continues to release planet-warming gases into our atmosphere, principally by burning coal, oil and fact, the number of days of extreme sea surface heat globally has tripled over the past 80 years, according to research published earlier this year."Global warming is the main driver of marine heat waves… it's essentially transferring heat from the atmosphere to the ocean. It's very simple," said Dr Mediterranean is particularly vulnerable because it's a bit like a bathtub, largely surrounded by continents rather than open means water cannot escape easily, so its surface heats up quickly in the presence of warm air, sunny skies and light winds - as happened in June. For that reason, the Med is "a climate change hotspot" said Karina von Schuckmann of Mercator Ocean International, a non-profit research heat peaked as June turned to July, after which stronger winds allowed deeper, cooler waters to mix with the warm surface above and bring temperatures temperatures remain above average and there could be consequences for marine life that we don't yet know about. Most life has a temperature threshold beyond which it can't survive, though it varies a lot between species and sea creatures can also suffer from prolonged heat exposure, which essentially drains their energy through the summer to a point where they can no longer cope."I remember four years ago diving in September at the end of summer, we found skeletons of many, many, many populations," said Emma Cebrian, an ecologist at the Centre for Advanced Studies of Blanes in and seagrasses act a bit like the forests of the Mediterranean Sea, home to hundreds of species, as well as locking up planet-warming carbon dioxide."Some of them are well adapted to typical Mediterranean warm temperatures, but actually they often cannot withstand marine heatwave conditions, which are becoming more extreme and widespread," said Dr Cebrian. The heat can also cause what ecologists call "sub-lethal effects", where species essentially go into survival mode and don't reproduce."If we start to see ecological impacts, there will almost certainly be impacts on human societies [including] losses of fisheries," warned Dan Smale, senior research fellow at the Marine Biological Association in Plymouth."We'll have to wait and see, really, but because the temperatures are so high this early in the summer, it is really alarming."The fast-warming Med is "a canary in the coal mine for climate change and marine ecosystems," he ocean heat can also supercharge extreme seas mean extra evaporation, adding to the moisture in the atmosphere that can fuel extreme other conditions are right, that can lead to devastating flooding, as happened in Libya in 2023 and Valencia in 2024. And warmer waters can reduce the cooling effect that coastal populations would usually get from the sea could make things very uncomfortable if there's another heatwave later in the summer, Dr Marcos warned."I'm pretty sure that's going to be horrible." Sign up for our Future Earth newsletter to keep up with the latest climate and environment stories with the BBC's Justin Rowlatt. Outside the UK? Sign up to our international newsletter here.
