Since the Industrial Revolution, surface ocean waters have become 30% more acidic due to the absorption of carbon dioxide, which disrupts the formation of coral reefs and the shells and skeletons of marine organisms.

Climate change threatens coral reefs by disrupting the symbiotic relationship between corals and algae due to rising ocean temperatures.

Ocean salinity comes primarily from eroded rocks, whose salts and minerals are carried into the sea by runoff, and from seawater dissolving salts and minerals from magma at seafloor openings.

The ocean's ability to store carbon long-term is being hindered by marine heatwaves

More than 4,000 robotic floats with biogeochemical data sensors, including oxygen, pH, nitrate, suspended particles, chlorophyll, temperature, and conductivity, have been deployed as part of the Global Ocean Biogeochemical Array. They have identified changes to ecosystem structure affecting the ocean's ability to transport carbon from surface waters into the deep.

Stony corals form a type of calcium carbonate called aragonite from ions brought to the ocean by rivers that have broken down terrestrial rocks.

The first coral reefs formed hundreds of millions of years ago from the carbonate skeletons deposited by hard corals.

By absorbing 90% of the thermal energy trapped by greenhouse gases, oceans are providing increasingly more energy to power the rapid strengthening of hurricanes.

Underwater volcanoes significantly contributes to marine extinctions during the Triassic period

An analysis of ocean basins in the Tibetan Plateau helped identify three major periods of volcanism—250-248, 233-231, and 210-208 million years ago—which released significant amounts of greenhouse gases, altering ocean chemistry. The low-oxygen conditions may help explain half of Earth's Triassic extinctions.

Carbon sinks absorb more greenhouse gases than they produce

The largest on Earth are oceans, which capture 25% of all carbon emissions and 90% of excess atmospheric thermal radiation while generating half of the world's oxygen. Wildfires and deforestation have reduced forests' net sink capacity, though fungi are believed to capture and store over a third of global carbon emissions.

Carbon dioxide acts as a 'control knob' for Earth's climate

Although Earth's ice ages were primarily triggered by slow changes in the planet's orbit—known as Milankovitch cycles—these changes do not explain the extreme temperature swings during glacial periods. Carbon dioxide acts as a feedback mechanism, intensifying both cooling during ice ages and warming during their ends by reinforcing the initial changes sparked by orbital shifts.

From 2023 to 2025, coral reefs experienced their fourth global bleaching event and the largest such event through 2025.

During coral bleaching, corals sacrifice their food source and expel colorful microorganisms to protect themselves, a phenomenon that resembles an organism's immune system attacking itself.

While major oil spills result from accidental pipeline ruptures or damage to transportation vessels or rigs, as much as half the oil that reaches coastlines has naturally leaked from the seafloor.

Over 1 million fish, marine mammals, and invertebrate species depend on coral reefs for habitats, camouflage, and food.

Deep water corals—located throughout the world's ocean basins at depths beyond 200 meters (660 feet)—slowly build small coral gardens in the dark with the help of underwater worms.

Research has found that when their symbiotic algae are not producing oxygen via photosynthesis, corals twirl hairlike structures to circulate water and draw oxygen into their outer tissues.

The top several meters of the world's oceans can hold as much thermal energy as the entire atmosphere, and their average surface temperature has increased by 0.9 degrees Celsius (1.62 degrees Fahrenheit) since the pre-industrial era.

Pearls form when a saltwater oyster or a freshwater mussel coats a parasite or other irritant that has entered its shell with concentric layers of calcium carbonate and organic protein.

Coral reefs get their colors from zooxanthellae—photosynthetic algae that line corals' digestive tracts and provide them with sugars in exchange for a home within this protective tissue.

Exposed concrete led to oxygen depletion within Biosphere 2

Instead of being absorbed by plants through photosynthesis to produce oxygen, significant amounts of carbon dioxide were taken up by the calcium hydroxide in the concrete, trapping the oxygen in calcium carbonate and water. This concrete was sealed before the start of the second B2 mission.

The cycling of carbon via tectonic activity may have facilitated life on Earth

Plates sinking into Earth’s mantle pull carbon from the surface, helping stabilize the atmosphere and climate by removing greenhouse gases from volcanic eruptions. At the same time, magma is a significant contributor of heavy metals and other crucial minerals for life to the surface.

Soil is the largest terrestrial carbon sink on the planet, storing almost twice as much carbon as the atmosphere and all living plants and animals combined.

Some corals absorb harmful ultraviolet radiation and re-emit it as visible light, thereby protecting symbiotic algae within their tissues and providing them with energy for photosynthesis.

Research has shown that some marine life can survive the extreme pressure of the deep ocean because of specialized molecules that strengthen proteins, enzymes, and cellular membranes.

The warmest waters in the ocean are found at hydrothermal vents—hot springs on the seafloor that discharge plumes of mineral-rich water heated by magma to temperatures over 370 degrees Celsius (700 degrees Fahrenheit).

Fish populations in the Great Barrier Reef have increased after installing waterproof speakers on the ocean floor that played recordings of sounds from healthy coral reefs.

How water pressure affects the body

The extreme conditions of the deep sea include increasing amounts of pressure as explorers and organisms descend into its depths. The major danger for both fish and humans is the way pressure changes how body tissues absorb chemical molecules...

When diving and snorkeling in environments containing reefs, avoid touching reefs, anchoring on them, or using sunscreen with active ingredients harmful to marine life.

Algae can capture carbon dioxide at rates up to 50 times faster than land-based plants and can be grown in tanks that use one-tenth the land footprint of terrestrial plants.

The Amazon rainforest is considered the 'lungs of the Earth,' but it contributes less than a quarter of the oxygen of phytoplankton—microscopic plants, algae, and bacteria capable of photosynthesis.

An analysis of fossilized reefs from northern Africa and Germany suggests that shallow water corals and photosynthetic algae formed the mutualistic partnership seen today between 419 and 359 million years ago.

The National Oceanographic and Atmospheric Administration estimates that US commercial and recreational fisheries valued at $200M depend on coral reefs, which provide up to $1.8B in flood protection by absorbing 97% of wave energy.

Why Earth would become a more deadly environment without the ozone layer

The ozone layer blocks almost all of the sun's harmful, including dangerous UVC rays that can damage cells by breaking chemical bonds. Without it, rates of skin cancer, crop failures, oceanic die-offs, and widespread ecosystem collapse would increase significantly, making Earth largely uninhabitable.

Starting with red, colorful objects will appear to lose their colors the deeper they are submerged because water scatters light, reducing the amount available to reflect off objects and be observed.

Carbon dioxide is the most produced greenhouse gas from human activities

In 2022, about 79.7% of US greenhouse gas emissions were carbon dioxide, produced through chemical reactions in processes such as cement production and the burning of fossil fuels, solid waste, trees, and other biological materials. Methane (11.1%), nitrous oxide (6.1%), fluorinated gases (3.1%), and trace amounts of solid and liquid aerosol were also created.