How Do Oceans Circulate? Crash Course Geography #9

Summary

The North Pacific Garbage Patch, a massive collection of trash spanning approximately 700,000 km2, illustrates the impact of ocean currents on global pollution. Driven by wind and differences in density and pressure, these currents transport debris like plastic across oceans, contributing to gyres where trash accumulates. The video explores how these currents, influenced by the Coriolis Effect and landmasses, shape marine ecosystems and affect global trade, underscoring the interconnectedness of pollution and the need for collective responsibility in addressing it.

Takeaways

• 🌊 The North Pacific Garbage Patch is a massive collection of trash vortices in the Pacific Ocean, mostly made of microplastics.
• 🌍 It is one of five large trash patches circulating in the world’s oceans, with plastic pollution visible even on beaches.
• 🌪️ Ocean currents, similar to wind patterns, are predictable flows of energy influenced by density and pressure differences.
• 🏝️ The size and movement of the North Pacific Garbage Patch are constantly changing, making it difficult to define its exact dimensions.
• 🌀 Ocean gyres, like the North Pacific Gyre, move trash across vast distances, powered by ocean currents and wind.
• 🧪 Water density is affected by both temperature and salinity, with warm water expanding and saltier water being denser.
• 🐟 Deep ocean currents play a crucial role in circulating nutrients and oxygen, supporting marine life and fisheries worldwide.
• 🚢 Modern marine debris is mostly plastic, with over 8 million metric tons of plastic waste polluting the oceans annually.
• 🚛 Shipping containers lost at sea contribute to ocean pollution, and international waters lack clear ownership for cleanup responsibility.
• 🌍 The interconnectedness of global ocean currents highlights how marine debris and pollution impact environments across the globe.

Q & A

What is the North Pacific Garbage Patch and how is it formed?

The North Pacific Garbage Patch is a massive collection of human-made trash, mostly composed of microplastics, chemical sludge, and wood pulp, circulating in the Pacific Ocean. It is formed by ocean currents that gather debris from various parts of the world into large areas known as gyres.

Why is it difficult to define the size of the North Pacific Garbage Patch?

The size is difficult to define because the Garbage Patch is not a solid mass of trash but rather a 'soup' of tiny microplastics that constantly move with ocean currents. Some scientists estimate it covers around 700,000 km², roughly the size of Texas.

How do ocean currents influence the movement of trash around the globe?

Ocean currents, driven by wind patterns and differences in water density, act like highways that move water and debris around the world. The trash can travel vast distances across oceans, getting caught in gyres and sometimes washing up on distant shores.

What is the role of the Coriolis effect in shaping ocean currents?

The Coriolis effect, caused by the Earth's rotation, deflects the movement of ocean currents, particularly as they move north or south. This creates curved paths, influencing the direction and flow of currents, which is stronger near the poles and weaker at the equator.

What are gyres, and how do they contribute to ocean circulation?

Gyres are large systems of circular ocean currents formed by global wind patterns and forces from Earth's rotation. They help circulate warm and cold water around the globe, moving marine debris, nutrients, and sometimes living organisms like fish or eels.

How do surface currents affect global climate?

Surface currents transport warm water from the equator towards the poles and cold water from the poles toward the equator. This movement regulates regional air temperatures, moderates climates, and plays a critical role in distributing heat across the planet.

What is the difference between surface currents and deep currents in the ocean?

Surface currents move horizontally across the top layer of the ocean, primarily driven by wind patterns. Deep currents, on the other hand, move more slowly at lower depths, driven by differences in water temperature and salinity, and play a key role in nutrient circulation.

How do deep ocean currents contribute to marine ecosystems?

Deep ocean currents are responsible for upwelling, which brings nutrient-rich water from the ocean floor to the surface. These nutrients support marine ecosystems and fisheries, particularly near coastal areas, which are vital for global fish harvests.

Why are plastic particles and other marine debris so persistent in the ocean?

Marine debris, especially plastics, do not biodegrade like organic materials. Instead, they are broken down by wind, waves, and sunlight into microplastics, which can persist for years in the ocean, often getting trapped in gyres and accumulating in garbage patches.

How does human activity contribute to marine pollution, and what challenges exist in addressing it?

Human activity, such as improper waste disposal, industrial pollution, and accidents like shipping container spills, contribute to marine pollution. Addressing this issue is challenging because trash in the oceans often crosses international boundaries and cleaning international waters is difficult to coordinate.