A mollusk swims up to a sea cucumber. The mollusk looks around at the reef and says (because in jokes everyone talks) to the sea cucumber, “I think we’re in hot water.” I’m no clownfish, but I think Marlin may have told this joke if Finding Nemo came out in 2024.
You might ask why a fish would make jokes about the temperature. Well, if you have been reading the news or following our blogs, you know the ocean is getting hotter due to humans burning fossil fuels. In fact, 90% of all global warming is occurring in our ocean. April 2024 was the thirteenth month in a row that the global monthly sea surface temperature was the warmest on record and the North Atlantic broke temperature records 421 days in a row. It’s not just the temperatures which are alarming but how much higher these temperatures are between now and previous years: 0.5°F more than previous years whereas previous records were often broken by a margin of 0.1°F or less. Warming is devastatingly worse than expectations.
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Imagine you were in your living room, and someone dialed up the thermostat. Would you be uncomfortable? Would you choose a different meal or a cold drink? Change locations? What if the temperature continued to rise?
Like humans, fish, marine mammals and all the living creatures in the sea are sensitive to temperature fluctuations, and unfortunately, rising temperatures are no joke for ocean life. Here are four ocean (of many) impacts that will continue to get worse without ambitious climate action:
- Coral bleaching
When temperatures rise in the ocean, corals become stressed and expel their symbiotic algae which produce the beautiful colors we associate with reefs (including Marlin and Nemo’s home). Without the algae, corals turn a ghostly white and become vulnerable to starvation and disease. Mass coral die offs have taken their toll on iconic reefs around the world, from Florida to the South Pacific. Clownfish, and other reef animals, suffer as well exhibiting stress, behavior changes and decreasing in abundance. - Fish on the move
Fish, and the other animals who depend upon them, prefer a specific temperature range. As waters warm, these species move towards Earth’s poles and deeper to find cooler water. Fish shifting their geographic range may see population declines. The climate-driven migration puts marine mammals, like whales, at risk because they are following these prey species and moving into new locations, which could bring them into contact with shipping lanes. Fishermen may have to shift the species they fish for or the locations where they fish, which has impacts on fishing-dependent communities. - Harmful algae blooms
Higher ocean temperatures, when combined with excess nutrients from water pollution (think runoff from stormwater, sewage overflows and agriculture), can result in more frequent and intense harmful algal blooms (HABs). These HABs, which have occurred in 82% of coastal countries, can create areas in the ocean with little to no oxygen and also produce toxins which kill marine animals and threaten public health and coastal economies. HABs are also found in Arctic waters as a result of ocean warming in this chilly region. - Coastal ecosystem loss
On top of these impacts, coastal ecosystems face additional threats from a hotter ocean, too. For example, oyster reefs along the coast (and people who eat them) are threatened by dangerous bacteria, like Vibrio, which thrive in warmer waters. Warmer water expands and causes glaciers and sea ice to melt; these impacts combine to result in higher sea levels. Sea level rise is drowning coastal plants like seagrass and causing erosion, especially during increasingly severe storms. Ocean warming is reducing the natural protection our coastal habitats offer to nearby communities.
A warmer ocean puts the whole world in hot water. The more we drill for and use oil and gas for energy and plastics, the hotter our ocean will continue to get.
But we can protect our ocean by phasing out oil and gas, including offshore drilling, and switching to renewable energy sources, such as responsible offshore wind and other marine renewable energy.
While this might mean building in the ocean, there are responsible and just ways to ensure offshore wind is safe for the marine environment and coastal communities. In the end, the long-term risks of climate change and inaction pose a far greater threat to the ocean and all life that depends on it.
Ocean Conservancy is leading the global push for 100% clean, responsible ocean energy by 2050 to help address climate change and protect the ocean. Join the fight by taking action to protect our ocean and coasts.
The post Four Impacts of Ocean Warming appeared first on Ocean Conservancy.
Ocean Acidification
Dr Heidarzadeh’s TV interview with SkyNews on the massive M7.7 Panama earthquake on 9 October 2026
Dr Heidarzadeh’s TV interview with SkyNews on the massive M7.7 Panama earthquake on 9 October 2026. Click here for the full story.
Dr Heidarzadeh’s TV interview with SkyNews on the massive M7.7 Panama earthquake on 9 October 2026
Our ocean is an incredibly vast and mysterious place. And there is no place where that is more evident than the deepest ocean area in the world: the legendary Mariana Trench. Located east of the Philippines, the Mariana Trench lies in the Mariana Archipelago in the western portion of the North Pacific. The greater area of the Mariana Trench Marine National Monument is made up of more than 95,000 square miles of ocean. Beneath these waters lie incredibly complex aggregations of submerged islands and volcanoes … and of course, an astoundingly massive trench.
Dive in with us to have your biggest questions answered about the famed Mariana Trench.
How deep is the Mariana Trench?
The deepest part of the Mariana Trench, known as Challenger Deep, is almost 36,000 feet below the ocean’s surface. For context, Mount Everest is about 29,000 feet above sea level, so the Mariana Trench is about 7,000 feet deeper than Mount Everest is tall. For one more comparison, the RMS Titanic lies at a depth of about 12,500 feet below sea level. The Challenger Deep is in waters nearly three times deeper than this ship’s final resting place.
Due to its enormous size, the Mariana Trench has at times been affectionately nicknamed the Grand Canyon of the ocean. This is certainly a picturesque image, but don’t let the mammoth size of this U.S. national terrestrial park fool you into thinking the Mariana Trench matches its size. The trench’s footprint is estimated to be 120 times larger than the Grand Canyon’s, and to reach the bottom of Challenger Deep, you’d need to descend through almost six Grand Canyons stacked on top of each other before you’d reach the seafloor.
Oh … and did we mention it’s five times wider than it is deep? It’s about 43 miles wide!
What is Challenger Deep, and how long would it take to reach it?
Challenger Deep is the deepest point of the Mariana Trench. Fewer than 30 people have ever journeyed to this area. The trek below the surface is long, dark and time-consuming, and it’s not an expedition considered lightly by scientists and explorers.
The first people to descend into the depths of this area in 1960 were oceanographers Jacques Piccard and Don Walsh, and it took them close to five hours to reach Challenger Deep. Since then, more advanced submersibles have been created, but it still takes two to four hours for modern vessels to reach such depths. For example, explorer and filmmaker James Cameron reached the seafloor in a little more than 2.5 hours in the first documented solo submarine dive to the area, and it took oceanographer Dr. Dawn Wright about four hours in 2022. It is crucial that these submersibles descend slowly and steadily beneath the surface, as the immense water pressure compounds with every mile a submersible descends. Speaking of pressure …
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What is the water pressure at the bottom of the Mariana Trench?
If you thought the depth of the Mariana Trench was its only jaw-dropping feature, think again. Water pressure is one of the most important factors affecting deep-sea life. In the ocean, pressure increases by one atmosphere for every 33 feet (10 meters) of depth. One atmosphere (a unit of measurement for pressure equivalent to average air pressure at sea level) is equal to about 14.7 pounds per square inch (PSI), which is the approximate standard atmospheric pressure at sea level. If you were to convert atmospheric pressure into weight, one atmosphere is about the weight of a bowling ball. Stay with me, friends.
If a vessel were to dive 2,000 feet below the surface, the pressure would equal that of 60 bowling balls stacked atop every square inch of that submersible. But 60 bowling balls is simply nothing compared to the pressure in the Mariana Trench. The atmospheric pressure at the depths of Challenger Deep is equal to about 16,000 PSI. That pressure is about the same as the weight of an entire full-grown elephant on every square inch of a submersible!
Need a more extreme comparison? If a human were to be placed at the bottom of the Mariana Trench, the pressure would be equal to that of 50 jumbo jets piled on top of a person!
Do any animals live in the Mariana Trench?
The depths of the Mariana Trench come with immense pressure and extreme darkness, but somehow, life finds a way to survive. Organisms that live at an extreme depth, like that of Challenger Deep, have to be highly adapted to low temperatures (typically just above freezing), high pressure and virtually no light at all.
Species found in the depths of the Mariana Trench might look vastly different from animals from other ocean depths because their anatomy has been refined to thrive in harsh conditions. At such great depths, these animals typically depend on chemosynthesis (using nutrient-rich waters being pumped out of hydrothermal vents) or descending detritus (dead matter that has fallen from higher parts of the ocean) for food, such as whale falls. Just a handful of these animals include species of octopuses and squids, sea cucumbers, amphipods, sea jellies, shrimp, sea worms and some wild-looking fish!
In 2025, more than 7,000 new species were discovered in the Mariana Trench, including the hadal snailfish (Pseudoliparis swirei). This is the deepest-dwelling fish currently known to science. Now, the fish has been dubbed “the Mariana snailfish.”
How was the Mariana Trench formed?
The process by which the Mariana Trench was created is a geologically fascinating one known as subduction. On the Earth’s surface, there are thin plates that cover the planet’s mantle, which is made of molten rock. If two of these plates collide, one pushes down into the Earth’s mantle while the other is pushed over the bottom plate. When this happens, a trench is formed from the drag of the bottom plate. This process can sometimes create incredibly strong earthquakes. The plates that forged the Mariana Trench’s creation are estimated to be up to approximately 180 million years old.
This trench was unknown to scientists until 1875. It was then that a team of explorers on the HMS Challenger measured the depth of the sea by simply lowering a weighted rope into the water. They were baffled when they measured that first portion of the seafloor to be five miles below the surface. And so was born the origin of some of the most daring deep-sea explorations known to mankind to date.
Is the Mariana Trench protected?
The Mariana Trench is in waters off Guam and the Mariana Islands. The region is protected from some human activities under its status as a marine monument. The creation of the Mariana Trench Marine National Monument signified that international, national and local leaders all recognize the importance of protecting this area.
However, just because the region is protected does not mean it’s not vulnerable to modern threats to ocean health. Plastic bags have been spotted in the Mariana Trench during several expeditions, highlighting the far-reaching impact of the marine debris problem. No corner of our ocean is safe from the ever-present threat of plastic pollution. The reality of a changing climate makes the future well-being of wondrous places like the Mariana Trench uncertain. What’s more: More than 70% of the global ocean has yet to be mapped. And what we don’t yet know about, we cannot wisely work to protect.
It’s up to us to work together to defend our ocean, from the sandy shores of our favorite beaches to the deepest, darkest parts of the sea. Together, we can work to protect our ocean as a whole, which ultimately helps protect treasured places like Challenger Deep.
Find out how you can join Ocean Conservancy’s wave of momentum to secure a healthy ocean and a thriving planet, forever and for everyone!
The post The Mysteries of the Mariana Trench appeared first on Ocean Conservancy.