Oceans and Coastal Margins

Ocean Currents

Ocean Currents

Surface ocean currents caused by prevailing winds blowing across the sea.

Gyres Ocean Currents

Dominant circular flow of surface ocean currents, clockwise in the northern hemisphere and anti-clockwise in the southern hemisphere.

Gulf Stream Ocean Currents

Narrow flowing current that transports heat northwards and then eastwards across the North Atlantic, creating mild winters and cool summers in the British Isles.

Nutrient Transfer due to Ocean Currents

Upwelling currents in eastern oceans move nutrient-rich cold water from the ocean flow to the surface.

Energy Transfer due to Ocean Currents

Warm currents from equatorial regions raise the temperature of polar areas, while cold currents may reduce summer temperature when wind blows from sea to land.

Specific Heat Capacity

The amount of energy needed to raise the temperature; water has a higher specific heat capacity than land.

Pacific Ocean

Two atmospheric states of warm surface water in the west and cold surface water in the east, causing a movement of water from colder areas to warmer areas.

Ocean Conveyor Belt/Thermohaline Circulation (THC)

Global circulation driven by the formation and sinking of deep water, responsible for a large flow of upper ocean water.

Thermocline

Boundary between surface waters and deeper layers, marked by rapid temperature change as depth increases.

El Niño

Reversal of normal atmospheric circulation in the southern Pacific Ocean, causing warm water and low pressure in the eastern Pacific.

La Niña

Intensification of normal atmospheric processes, causing a cold current to flow from the east across the equatorial Pacific Ocean.

Hurricanes (Tropical Cyclones)

Low-pressure systems with high-intensity rainfall, strong winds, and heavy waves; originate from moist, tropical seas.

Typhoon Haiyan, Philippines

Devastating typhoon with strong winds and high storm surge, causing significant damage and loss of life.

Ocean Acidification

Absorption of CO2 by oceans, leading to a decrease in pH and threatening species such as fisheries and coral reefs.

Ocean Role and Acidification

Oceans act as a source and store of carbon dioxide, absorbing and releasing it through various processes.

Coastal Environments

Influenced and shaped by physical and human processes, including lithology, geological structure, erosion, deposition, sea-level changes, human impacts, and ecosystem type.

Waves

Controlled by wind strength, duration, distance of open water, and depth; can be swell waves or storm waves.

Wave Refraction

Waves approaching an irregular coastline, causing wavefronts to break parallel to the shore and concentrate energy onto headlands.

Sediment Supply

Littoral cell system balancing input and output of sediment in coastal processes.

Features of Erosion

Bays, bayhead beaches, sea caves, arches, stacks, wave-cut platforms, and cliffs.

Features of Deposition

Spits, tombolos, beaches, sand dunes, and dune systems.

Advancing and Retreating Coastlines

Isostatic and global changes in sea level leading to either erosion or deposition.

Coastal Erosion and Flooding Management Strategies

Options include doing nothing, maintaining existing defenses, improving defenses, or managing retreat; can be achieved through hard or soft engineering techniques.

Cost-Benefit Analysis of Coastal Defense

Evaluating the costs and benefits of building and maintaining coastal defenses.

Conflicting Pressures on Coastlines

Balancing the needs of different stakeholders in coastal management, such as fishermen and tourism-related users.

Managing Coral Reefs

Importance of coral reefs for biodiversity, seafood, medicine, coastal protection, and economic value; threats from human activity and climate change.

Marine Protected Areas (MPAs)

Designated areas in the ocean that restrict harmful activities and aim to conserve sensitive ecosystems.

Managing Mangrove Swamps

The sustainable management and conservation of salt-tolerant forests that grow in tidal estuaries and coastal zones of tropical areas.

Integrated Coastal Zone Management (ICZM)

A management approach developed to address population growth and the destruction of mangroves, focusing on the sustainable use of coastal resources.

Sovereignty Right of Nations

The exclusive rights of coastal nations over the economic resources of the sea, seabed, and soil within their Exclusive Economic Zone (EEZ).

Exclusive Economic Zone (EEZ)

The area extending up to 200 nautical miles from a coastal nation's shore, where the nation has sovereign rights over the economic resources.

Developing Abiotic Resources

The extraction and exploitation of natural resources found in the ocean, such as manganese, cobalt, copper, and nickel.

Hydrates

Compounds of methane molecules trapped in water, found in permafrost and beneath the ocean surface, with potential as an energy source.

Oil

The exploration and extraction of oil reserves in various regions, such as the Gulf of Mexico, South China Sea, and North Sea, with associated environmental risks.

Illegal Fishing

The unauthorized and unregulated fishing activities that contribute to overfishing and the depletion of fish stocks, often monitored through satellite tracking systems.

Aquaculture

The commercial farming of fish, which involves raising fish in controlled environments and has both economic and environmental implications.

Initiatives to Manage Oceanic Pollution

Efforts to address marine pollution, including the management of plastic waste, radioactive waste, and other forms of litter that pose economic and environmental risks.

Chinese Expansion in South China Sea

China's territorial claims and military activities in the South China Sea, which have geopolitical implications and pose challenges to regional stability.

Changes in the Arctic

The melting of sea ice in the Arctic, which opens up new trade routes and access to oil and gas reserves, leading to territorial disputes and environmental concerns.