Ocean is a large body of salty water that covers 71% of Earth’s surface. It is the largest living ecosystem, home to countless species including fish, plants, and marine mammals.
Its vast expanse and complex chemistry make it a fascinating system. Scientists study its natural processes to understand how it works, and its role in regulating Earth’s climate, as well as its potential to provide resources and habitat for humans.
The ocean is divided into zones based on physical and biological characteristics. The photic zone is the area at the surface where sunlight can reach, and is where plants (free-floating phytoplankton) and microscopic bacteria produce organic compounds using light, water, and carbon dioxide.
Beyond the photic zone, oceanographers divide the ocean into a number of different regions based on water temperature and chemical properties. The warmest waters are in the tropics, with temperatures up to 30 degC (86 degF). In colder areas, near the poles where sea ice forms, surface temperatures can drop as low as -2 degC (28 degF).
Water in the ocean is constantly moving from one place to another. This movement is called the water cycle, and it moves water from polar glaciers to tropical rainforests, back to polar glaciers, and into the deep ocean.
Scientists are still discovering what’s beneath the ocean’s surface, but we do know that its bottom is not flat. It’s full of features like ridges, trenches, and plateaus. USGS scientists use sonar to map the ocean floor and understand what’s there, and to discover how it changes over time.
There are many ways that human activities can impact the ocean. They can cause pollution, which is when chemicals or other substances enter the environment and have an adverse effect on organisms and their habitats. They can also increase the amount of carbon dioxide gas in the atmosphere, which causes ocean acidification.
Oceans are a vital part of the global food chain, and they supply oxygen and other nutrients to the planet. In addition, they play an important role in global climate by absorbing extra carbon dioxide from the air and buffering the effects of global warming.
The oceans are also a source of energy, and they support many important industries. For example, the fisheries that catch and process ocean fish contribute to human food supplies around the world. Other ocean industries include tourism, mineral mining, and energy production. However, ocean pollution is a serious problem. It occurs when pollutants such as industrial and agricultural waste, particles, noise, excess carbon dioxide, and invasive species enter the ocean and harm its ecosystems. The majority of this pollution comes from land-based sources, but marine transportation also contributes. This problem has led to international treaties to protect the oceans from pollution.