What Is Oceanography?
OCEANOGRAPHY is the science of OCEANS — covering 71% of Earth's surface. It has four main branches. PHYSICAL: waves, currents, tides, temperature. CHEMICAL: salinity, dissolved gases, ocean chemistry. BIOLOGICAL: marine life from microbes to whales. GEOLOGICAL: seafloor, plate tectonics, sediment. Oceans regulate climate, feed billions, and host more biodiversity than any other environment on Earth.
Big numbers. The ocean holds 97% of Earth's water. AVERAGE depth: 3,700 m (12,000 ft). DEEPEST point: Mariana Trench, ~11,000 m. Most of the ocean is COLD (~2-4°C in deep waters) and DARK (no sunlight below ~200 m). The deep sea is one of the LEAST explored environments on Earth — we have better maps of Mars than of much of our seafloor.
How much of Earth's seafloor has been MAPPED in detail (by sonar)?
Why oceans matter. (1) CLIMATE: oceans absorb heat and CO2; ocean currents move heat globally. (2) FOOD: billions of people depend on seafood. (3) OXYGEN: marine plants produce ~50% of Earth's oxygen. (4) BIODIVERSITY: most species on Earth live in oceans. (5) ECONOMY: shipping, fisheries, tourism. (6) STORM SYSTEMS: form over warm ocean water. Healthy oceans = healthy planet.
Ocean Day
For ONE day, count things in your life that depend on oceans: weather, food (seafood), products shipped overseas, oxygen, climate. The ocean reaches everywhere.
Oceans are Earth's greatest mystery and greatest support. Understanding them is essential to understanding our planet.
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