The largest ocean on Earth is filled with mysteries, but also subject to great pressures like climate change, plastic pollution, and overfishing.
The Pacific Ocean is the largest and deepest ocean on Earth. It spans 60 million square miles from California to China, and in certain regions extends tens of thousands of feet below the surface of the water.
To get a sense of just how immense the Pacific Ocean is, you could put all of Earth’s landmasses together, and the Pacific would still be larger.
The name Pacific is a version of pacify or peaceful. It was named by the explorer Ferdinand Magellan in 1520 as he sailed through a calm patch of water on the ocean. Despite its name, the Pacific is a vast body of water teeming with activity. Much of the ocean is still waiting to be explored, but human activities like industrial fishing, deep-sea mining, and fossil-fuel burning are already changing it in significant ways. The vast body of water is home to some of the most unique life forms on Earth and contains the deepest reaches known to humankind.
The Pacific Ocean stirs up some of the strongest hurricanes ever seen. For example, in 2018 the strongest storm of the year was Super Typhoon Mangkhut. It hit the Philippines in late September before dissipating over mainland China. At its strongest, the storm’s winds topped 165 miles per hour, uprooting trees, destroying homes, and causing deadly mudslides.
Hurricanes, typhoons, and cyclones are actually different names for the same weather pattern. Hurricane is used in the eastern Pacific, typhoon in the northwestern Pacific, and cyclone in the southwestern Pacific. The storms feed on the energy of warm water, making the Pacific a powerful breeding ground for them.
The Ring of Fire
The Pacific basin is called the “Ring of Fire” because of the area of earthquake and volcanic activity around its edges. The resulting chain of volcanoes is roughly 25,000 miles long and springs to life where the Pacific tectonic plate slides against or collides into the other tectonic plates that circle it. The subduction of tectonic plates—when a plate slides beneath another one—in certain areas also helps form deepwater trenches.
The Mariana Trench
The Mariana Trench is one such deep ocean trench that sits along the Ring of Fire in the Mariana Archipelago east of the Philippines. It’s the deepest known spot on the planet—deeper than Mt. Everest is tall, reaching down roughly seven miles. The deepest point in the trench is called Challenger Deep, at 36,000 feet down.
Humans descended into the Challenger Deep in 1960 inside a U.S. Navy submersible, and film director and explorer James Cameron made a solo trip in 2012. Today, scientists periodically send remotely operated vehicles to the bottom of the trench for various research purposes.
Scientists are just beginning to learn about life in the deepest parts of the oceans. Creatures in the deep sea exist in waters with zero light, crushing pressure, and conditions no human could ever survive. Yet the deep sea is home to a diverse group of sea creatures with mysterious lives, from glowing lures to huge eyes. Scientists know little about many of these creatures and the roles they may play in the global ecosystem because they are so hard to study.
Ocean acidification and ‘the blob’
Burning fossil fuels and releasing carbon dioxide into the air doesn’t just alter the makeup of our atmosphere. Oceans, which absorb about 30 percent of the CO2 released into the atmosphere, are also highly susceptible to the changes taking place in a warming world. When that carbon is absorbed, a series of chemical reactions takes place that produces more hydrogen ions and leads to more acidic waters. According to NOAA, the ocean’s pH has dropped by 0.1 pH units in the past 200 years. That equates to ocean waters that are 30 percent more acidic. More acidic water is making it harder for organisms that make shells out of calcium carbonate, like clams and corals, to survive.
From 2014 to 2016, a warm weather anomaly often referred to as the blob was responsible for killing off high percentages of marine life in the Pacific. On the U.S. West Coast, many marine mammals like sea lions and otters were turning up dead. Some scientists have since speculated that the Pacific blob was a sign of what life may be like in a warming world.
Scientists haven’t conclusively found an explanation for what caused the blob. Some have suggested it’s at the extreme end of a cyclical ocean weather pattern, while many say anthropogenic climate change has created the perfect conditions to concentrate intense, warm ocean water over the eastern Pacific.
Great Pacific Garbage Patch
Between Hawaii and California is an area larger than the state of Texas that has been dubbed the Great Pacific Garbage Patch. Though the name may conjure up a massive island of plastic jutting out of the sea, 94 percent of the plastics found in the patch are actually microplastics—tiny pieces of plastic smaller than a grain of rice and often impossible to see with the naked eye. Much of the heaviest plastic found in the patch is abandoned fishing gear, often referred to as “ghost nets.” Ghost nets threaten marine life because they can easily ensnare animals swimming by.
The garbage patch in the Pacific is the largest known on the planet, but several others can be found in other oceans (five main ones are often reported). Debris tends to collect in swirling, circular currents called gyres.
Experts say that cleaning up the patch entirely is likely impossible, but some are trying to at least mitigate the problem. One Dutch company called Ocean Cleanup has invested $32 million as of early 2019 in cleaning up the Pacific Garbage Patch. Early ocean trials have so far shown mixed results.
Billions of people around the world rely on fish as their primary source of protein and millions rely on it for their livelihood. Many of the world’s populations of wild fish harvested for humans to eat are now overfished, or over exploited beyond what the fish can replace through reproduction. The precise number is often debated by conservationists but the United Nations has estimated about a third of global fisheries are overfished. Whether a mile off a country’s coast or far out to sea, overfishing affects much of the Pacific Ocean, although there have been encouraging signs that some fisheries are recovering.
Successful fisheries managers monitor the health of their stocks regularly to dictate when a region can be fished, how much, and when “no-take zones” should be created to allow a population more time to reproduce and multiply.
The Pacific Ocean is also the site of much of the world’s high seas fishing, both legal and illegal, a practice that has been criticized by conservationists as being unsustainable as well as unprofitable. Recent international discussions have raised the question of whether nations should unite to limit or even prohibit fishing on the high seas, which currently faces few restrictions.