Oceanography:Ocean Currents & Their Effects| UPSC Notes
Oceanography is the scientific study of oceans, including their physical, chemical, biological, and geological aspects. It explores the vast marine ecosystems, the movement of ocean currents, and the interactions between the oceans and the atmosphere. Oceanography plays a crucial role in understanding global climate patterns, marine life, and the impact of human activities on ocean environments.
Oceanography provides insights into how ocean currents influence climate by distributing heat across the planet, affecting weather patterns and coastal temperatures. It helps predict natural disasters like tsunamis and storm surges by studying ocean dynamics.
The study of Oceanography aids in managing marine resources, including fisheries, by understanding marine biodiversity, ecosystems, and the impacts of overfishing, pollution, and climate change on ocean health.
Technological advancements in Oceanography include satellite observations and deep-sea exploration, which have expanded our knowledge of the ocean’s role in global carbon cycling, supporting sustainable management of marine environments.
Types of Ocean Currents
Ocean currents are the large-scale movements of water that originate due to variations in wind, temperature, and salinity. There are two types of the above currents: surface currents and deep-water currents, which are as follows:
Surface Currents
Gyres: The large systems of the circular ocean currents that are formed by global wind patterns and forces developed by the Earth’s rotation. The five major ocean gyres include the North Atlantic, South Atlantic, North Pacific, South Pacific, and Indian Ocean gyres.
Example: The North Atlantic Gyre includes the Gulf Stream, one of the strongest, warmest, and fastest Atlantic Ocean currents, found to have its origin in the Gulf of Mexico and flow into the Atlantic from the southeast coast of the United States.
The Gulf Stream is one of the strong warm ocean currents that originates from the Gulf of Mexico, travels up the eastern coast of the United States, and crosses the Atlantic Ocean towards Europe. It is one of the strongest and transports warm water and influences the climates along the eastern coast of North America and Western Europe.
Deep-water currents also known as Thermohaline Circulation:
Characteristics: It is due to density differences caused by temperature (thermo) and salinity (haline). Water that is denser sinks, while water that has less density rises. Cold, salty water sinks, and warm, less salty water floats up.
Example: The Global Conveyor Belt is a system of deep-ocean circulation based on the effects of temperature and salinity. That system regulates Earth’s climate by redistributing heat around the planet.
Driving Forces
Wind: The greatest driving force behind surface currents. Wind blows across the ocean’s surface and provides those currents.
Coriolis Effect: Moving objects, including ocean currents, get deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere due to the Earth’s rotation.
Temperature and Salinity: Changes in temperature and salinity between water masses cause differences in density, which drive thermohaline circulation.
Gravitational Forces: Tides, resulting from gravitational pull from both the Moon and the Sun, add additional motion to the ocean currents.
Effect on Climate
Ocean current affects climate; they distribute heat around the world. Flows influence the coastal climates and patterns of weather and, eventually, are used to drive global climate systems and affect the marine or human environment of the entire globe.
El Niño and La Niña Phenomena
El Niño: A periodic warming of the sea surface temperatures in the central and eastern Pacific Ocean, which, in turn, disrupts the normal pattern of weather, hence causing abnormal situations like heavy rains and droughts and changes in the behavior of winds.
Effect on Climate: Brings heavy rainfalls in Peru and the southern United States, a drought in Australia and Indonesia, and increases global temperatures.
Case study: extreme weather across the globe, from flood and drought and economic loss in many regions, was associated with the 1997-1998 El Niño.
La Niña: The opposite of El Niño, characterized by anomalous cool ocean temperatures in the Equatorial Pacific. La Niña generally follows an El Niño, but it also has the potential for extreme departures of weather patterns.
This causes droughts in Australia and Indonesia, dry weather in the southern United States, and cooler global temperatures.
Case History: The La Niña 2010-2012 event led to severe flooding in Australia and caused drought in the southern United States.
Global Effects on Weather Patterns
Changes in ocean currents are one of the major causes of changes in weather patterns, influencing precipitation, temperature, and storm frequency.
Ocean currents play an important role in shaping the global weather through conducting warm and cold water all over the planet. The warm Gulf Stream is the reason for warming the climate in Western Europe, while a very cold California Current cools the west coast of the United States.
Marine Ecosystem
Marine ecosystems are quite complex and include, among others, oceanic environments, coral reefs, estuaries, and enclosed seas. They support an incredibly vast array of species and have a critical role in regulating global climate, carbon cycling, and resources for human livelihoods and economic activities.
Coral Reefs
Characteristics: A coral reef is a diverse underwater ecosystem held together by calcium carbonate structures secreted by corals.
Characteristics: Mangroves are tropical and subtropical coastal forests. They provide important habitat for several species, offer protection against shoreline erosion, and support carbon sequestration.
Conservation Efforts: Mangrove afforestation initiatives, regulation over mangrove areas through legal protection, sustainable management.
Deep-Sea Ecosystems
Features: These are located at depths where sunlight cannot reach them.
Threats: Over-mining the deep sea, overfishing, and pollution.
Conservation Efforts: International regulating legislation to curb deep-sea mining; setting up of marine protected areas for the deep sea; and responsible fishing.
Human Activities and the Oceans
These activities lead to disruptions of the marine ecosystem, degradation of biodiversity, and acceleration of climate changes with adverse effects on the health of the ocean and those vital resources for man’s survival.
Shipping routes
Oceans enable international trade because of the wide shipping routes that bring parts of the world together. Despite these, shipping has undergone detrimental effects on the environment in terms of oil spills, marine pollution, as well as the introduction of invasive species through ballast discharge.
Fishing Industries
The oceans are a huge source of food and employ many people who fish. Over-fishing reduces the amount of fish stock and marin ecosystems. The answer lies in sustainable fishing and regulation across nations.
Oil Drilling
Offshore oil drilling is a huge industry in the provision of energy resources. However, it has brought about huge environmental risks such as oil spills, habitat destruction, and pollution. There have been efforts to regulate this aspect while technology evolves to make things safer.
Environmental Impacts and Regulations
Pollution: Marine pollution due to plastics, oil spills, and chemicals is one of the significant threats to ocean health. Internationally agreed rules locally implemented to reduce pollution and protect marine habitats are in place.
Climate Change: An increase in global temperature and acidification of the ocean through absorption of excess CO₂ is one of the major threats to marine life. Reduction of greenhouse gas emissions and safeguarding of marine habitat are several measures toward the battle against climate change.
By conserving: marine protected areas; international agreements such as the MARPOL Convention, which prevents marine pollution; efforts at local conservation contribute to the preservation of marine ecosystems.
Conclusion
Other than knowing the consequences of oceanography for climate, marine ecosystems, and human activity, understanding ocean currents and what they imply takes a greater importance. One needs to know these subjects as a UPSC aspirant since many questions during the examination will encompass geography, environment, and sustainable development.
Oceanography UPSC Notes
1. Oceanography is the study of the physical, chemical, and biological properties of the oceans. 2. It examines ocean currents, marine ecosystems, and their role in regulating climate patterns. 3. Ocean currents are driven by wind, temperature, and salinity differences, influencing global weather and climate systems. 4. The oceans play a key role in the carbon cycle, absorbing significant amounts of atmospheric carbon dioxide. 5. Human activities like overfishing and pollution are major threats to marine biodiversity and ecosystems. 6. Oceanography helps in understanding coastal processes, aiding disaster management for events like tsunamis and storm surges. 7. Marine resources, such as fisheries and minerals, are critical for economic development and food security. 8. Technological advancements, such as satellite imagery and deep-sea exploration, have expanded our understanding of ocean dynamics.