Latest news with #OceanColourWeb
News18
2 days ago
- Science
- News18
Why Are Earth's Oceans Getting Darker And Should We Be Worried?
Last Updated: A new study has revealed that over one-fifth of the global ocean has lost sunlight in just two decades, a quiet shift with potentially profound consequences It's not something you can see with the naked eye, but it's happening at a planetary scale. Earth's oceans are getting darker—and fast. In just 20 years, more than 21 per cent of the global ocean has lost measurable sunlight, according to a sweeping study led by the University of Plymouth in collaboration with the Plymouth Marine Laboratory, based on satellite data from 2003 to 2022. The findings are based on two decades of satellite data from NASA's Ocean Colour Web, which tracks changes in how sunlight penetrates ocean surfaces globally. Covering over 75 million square kilometres, this reduction in ocean light is compressing the photic zone—the sunlit layer of the sea where marine life thrives and photosynthesis occurs. But what's behind this shift? And why should we care? What's Causing Ocean Darkening? Scientists point to multiple, overlapping reasons: Runoff and sedimentation: In coastal regions, fertilisers, sewage, and industrial waste flow into the sea. This triggers algal blooms and increases turbidity, both of which block light from penetrating the water column. Climate-driven shifts in plankton: Rising sea surface temperatures are changing the distribution, size, and composition of phytoplankton—microscopic organisms that not only form the base of the food chain but also reflect or absorb sunlight depending on their type. Rainfall and erosion: Heavier monsoon patterns and land-use change are sending more sediment into the oceans, especially in the tropics and around the Indian subcontinent. Loss of water clarity: In the open ocean, changes in biological productivity—likely climate-induced—are altering how much light the sea absorbs. advetisement While some regions have experienced slight brightening, particularly in clearer mid-ocean zones, the overall global trend points decisively toward darkening. Why This Is A Red Flag The compression of the photic zone is not just a biological concern—it's a planetary one. Disrupts marine food webs: Phytoplankton need sunlight to grow. Less light means fewer plankton, and that ripples up the chain to fish, marine mammals, and seabirds. Weakens ocean's climate role: Phytoplankton are critical to the carbon cycle, absorbing CO₂ and helping cool the planet. Less sunlight means reduced photosynthetic activity and a shrinking oceanic carbon sink. Pushes species into shallow zones: With the sunlit layer shrinking, marine life is being squeezed into shallower, warmer waters—making them more vulnerable to heat stress, overfishing, and habitat loss. This compression may also affect coastal economies dependent on fishing, as marine species shift or decline in response to changing light conditions. 'Our results provide evidence that such changes cause widespread darkening that reduces the amount of ocean available for animals that rely on the sun and the moon for their survival and reproduction," said Dr Thomas Davies, Associate Professor of Marine Conservation at the University of Plymouth, and co-lead author of the study Darkening of the Global Ocean, published in Global Change Biology in May 2025. 'We also rely on the ocean and its photic zones for the air we breathe, the fish we eat, our ability to fight climate change, and for the general health and wellbeing of the planet. Taking all of that into account, our findings represent genuine cause for concern." A Call To Action Experts stress that reversing or even slowing ocean darkening will require action on multiple fronts: curbing land-based pollution, adapting coastal infrastructure, and most urgently, addressing climate change at a global scale. The study also highlights the importance of expanding marine observation networks, which are currently underfunded and patchy across vast parts of the ocean. For now, one thing is clear: the world's largest ecosystem is losing its light. And that should never be taken lightly. Watch India Pakistan Breaking News on CNN-News18. Get breaking news, in-depth analysis, and expert perspectives on everything from geopolitics to diplomacy and global trends. Stay informed with the latest world news only on News18. Download the News18 App to stay updated! First Published:
Daily Mirror
3 days ago
- Science
- Daily Mirror
Ocean darkening' warning as fifth of the world's waters undergoes transformation
A new study has warned that a significant portion of the world's oceans is undergoing a mysterious process known as "ocean darkening" - and the consequences could be dire A staggering fifth of the world's oceans have plunged into darkness over the past two decades, a dramatic shift that could spell disaster for marine life worldwide. Oceanographic Magazine has reported on a major new study revealing that more than 75 million square kilometres of ocean - including vast coastal areas and open waters - have experienced what experts are chillingly terming "ocean darkening." This process, observed between 2003 and 2022, involves the photic zone - the sunlit upper layers of the ocean where a whopping 90% of all marine life flourishes - shrinking dramatically as less light penetrates the water. Alarmingly, researchers from the University of Plymouth and Plymouth Marine Laboratory report that over 9% of the ocean (an area larger than Africa) has seen photic zones retreat by more than 50 metres, while 2.6% has seen a drop of more than 100 metres. While the full implications remain uncertain, scientists fear it could affect "huge numbers of the planet's marine species and ecosystem services provided by the ocean as a whole.", reports the Express. However, it's not all doom and gloom. Around 10% of global oceans - some 37 million square kilometres - have actually grown lighter over the same period, with changes possibly linked to plankton communities, rainfall, and agricultural runoff. Dr Thomas Davies, Associate Professor of Marine Conservation at the University of Plymouth, explained:. "There has been research showing how the surface of the ocean has changed colour over the last 20 years, potentially as a result of changes in plankton communities. "But our results provide evidence that such changes cause widespread darkening that reduces the amount of ocean available for animals that rely on the sun and the moon for their survival and reproduction." He added: "We also rely on the ocean and its photic zones for the air we breathe, the fish we eat, our ability to fight climate change, and for the general health and wellbeing of the planet. Taking all of that into account, our findings represent genuine cause for concern." The team analysed two decades of satellite data using NASA's Ocean Colour Web, which breaks the global ocean into 9km-wide pixels. Light availability was then calculated using a high-tech algorithm to estimate photic zone depth. Among the most affected areas are the Arctic and Antarctic, and the Gulf Stream, which are already undergoing some of the most dramatic transformations on the planet due to climate change. Closer to home, the UK's waters have seen mixed results. The North Sea, Celtic Sea, parts of the English and Scottish east coasts, Wales, and the Irish Sea have darkened - while the English Channel and northern waters near Orkney and Shetland have brightened. Professor Tim Smyth, from the Plymouth Marine Laboratory, issued a stark warning about the underappreciated dynamism of the ocean: "The ocean is far more dynamic than it is often given credit for. For example, we know the light levels within the water column vary massively over any 24 hour period, and animals whose behaviour is directly influenced by light are far more sensitive to its processes and change." He went on to highlight the potential ecological impact, "If the photic zone is reducing by around 50 metres in large swathes of the ocean, animals that need light will be forced closer to the surface where they will have to compete for food and the other resources they need." Smyth stressed this could precipitate dramatic shifts in marine life: "That could bring about fundamental changes in the entire marine ecosystem." His remarks accompany the publication of a pivotal study, 'Darkening of the Global Ocean', recently featured in Global Change Biology.
Time of India
3 days ago
- Science
- Time of India
Oceans are getting dark, why it's a wake up call for humanity
Over 21% of the world's oceans have darkened significantly in the last two decades, reducing sunlight penetration into the photic zone, the sunlit upper layer vital to marine life. Tired of too many ads? go ad free now This worrying trend, revealed through nearly 20 years of satellite data, is not just an environmental issue but a planetary one. The shrinking photic zone threatens marine biodiversity , disrupts ecosystems, and could weaken the ocean's ability to support life, regulate climate, and produce oxygen. Scientists now warn that this change should serve as a global wake up call, reminding us how closely our future is tied to the health of the oceans. What is ocean darkening? Ocean darkening refers to the reduction in water clarity that limits how far sunlight can penetrate into the ocean. The photic zone, where light supports photosynthesis and marine food webs begin, is shrinking in many regions. This change can be caused by increases in: Nutrients and sediments from agricultural runoff Algal blooms triggered by warming seas Organic material from rainfall and soil erosion Climate-induced changes in ocean surface temperature and current patterns What the research reveals about reduced sunlight Scientists from the University of Plymouth and Plymouth Marine Laboratory analysed satellite data from NASA's Ocean Colour Web spanning 2003 to 2022. Their findings include: 21% of ocean area darkened, totalling over 75 million square kilometres 9% of the ocean saw photic zones shrink by over 50 metres In extreme cases, depth reduction exceeded 100 metres While 10% of the ocean became lighter, the darkening trend dominates Regions such as the Gulf Stream, Arctic, Antarctic, and enclosed seas like the Baltic showed the most significant changes. Threats to marine life The sunlit zone is home to the majority of oceanic life, from microscopic plankton to fish and larger predators. Darkening waters push light-dependent species closer to the surface, leading to: Increased competition for food and space Disruption in feeding, migration, and reproduction patterns Stress on plankton communities, which are the base of the marine food chain This not only affects biodiversity but could destabilise entire ecosystems. Tired of too many ads? go ad free now Why ocean darkening matters to humanity This is not just a marine crisis, as humans are deeply connected to ocean health . The shrinking photic zone affects: Oxygen production: marine phytoplankton produce over 50% of Earth's oxygen Food security: a disrupted ocean food web threatens global fisheries Climate regulation: oceans absorb carbon dioxide and heat, and changes in biological activity may reduce this capacity Regional impacts: A mixed picture Not all areas are darkening equally: Darkening: coastal waters of the North Sea, Celtic Sea, eastern England and Scotland, and the Irish Sea Lightening: the English Channel and waters north of Scotland to Orkney and Shetland These mixed trends highlight the complexity of factors at play, including regional climate effects, rainfall patterns, and human land use. A global wake up call The ocean is more dynamic and sensitive than often perceived. Professor Tim Smyth stresses that even minor reductions in light availability can fundamentally shift marine ecosystems . When photic zones shrink, marine life is squeezed into shallower layers, altering behaviours, survival rates, and ecological balances. This research is not a prediction, it is a documented transformation already underway. It signals the urgent need for: Better land and ocean management Reduced agricultural runoff Climate change mitigation mitigation Sustained ocean monitoring Conclusion: Time to take action Ocean darkening is more than a scientific observation, it is a clear signal that Earth's systems are under stress. Humanity must pay attention. Our oceans not only host life below water but also support life on land. If the light in our oceans fades, the consequences will ripple across ecosystems, economies, and generations. This is the time to act, not just to save marine life, but to secure a liveable future for us all.
