Why is most of the ocean still unexplored? - What in the World podcast, BBC World Service

Key Concepts:

• Ocean exploration challenges (pressure, darkness, cold, vastness)
• Mariana Trench and Challenger Deep
• Submersible technology and robotic exploration
• Dark oxygen and its potential implications
• Seamounts and varied seafloor terrain
• Newly discovered marine species and their adaptations
• Importance of ocean research for climate change and resource management
• Biological/biochemical carbon cycle
• Deep sea mining and its controversies

1. Ocean Exploration Challenges:

• Pressure: The immense water pressure at the ocean's depths poses a significant challenge. At the bottom of the ocean, the pressure is a thousand times greater than at the surface. This extreme pressure makes it difficult for humans and equipment to operate.
• Lack of Light: Sunlight cannot penetrate deep into the ocean, resulting in perpetual darkness. This lack of light makes it difficult to observe and study the environment.
• Cold Temperatures: The temperature in the deep ocean is extremely cold, typically around three or four degrees Celsius. This cold environment requires specialized equipment and adaptations for organisms to survive.
• Vastness: The oceans cover 70% of the Earth's surface, making exploration a vast and expensive undertaking. Exploring even a small area of the ocean requires significant resources and time.
• It's easier for astronauts to explore space than it is to reach the ocean floor.

2. Mariana Trench and Challenger Deep:

• The Mariana Trench is the deepest part of the ocean.
• Challenger Deep, the deepest point within the Mariana Trench, was first explored in the 1960s by Jacques Piccard and Don Walsh in a US Navy submersible. Their initial exploration was limited due to dust and material stirred up by the submersible.
• James Cameron, the filmmaker, later explored the Challenger Deep and captured footage, providing a better view of this deep-sea environment.
• A 2019 voyage involved a man spending 3.5 hours descending, 2 hours at the bottom, and 4 hours ascending, highlighting the slow decompression process required to avoid death due to pressure changes.
• The footage revealed a cavernous environment covered in sediment and plumes of dust, with the discovery of numerous new species.
• The Mariana Trench is so deep that if Mount Everest were flipped over and placed in it, the peak would still not reach the bottom.

3. Submersible Technology and Robotic Exploration:

• Modern technology allows for advanced ocean exploration using submersibles and robots.
• Robotic submarines can operate for weeks or months, equipped with cameras, lights, and robotic arms.
• These robots collect samples of rocks, gases, sediment, and various life forms, including bacteria, phytoplankton, fish, and corals.
• The technology allows scientists to film plumes of gas or dust coming from the sea floor.

4. Dark Oxygen:

• The discovery of "dark oxygen" challenged the scientific consensus that oxygen could not exist at the bottom of the ocean due to the absence of light for photosynthesis.
• Evidence suggests that metallic nodules on the seafloor may split hydrogen and oxygen, creating this dark oxygen.
• This discovery, though still under investigation, could indicate a different form of oxygen sustaining life in the deep sea.

5. Seamounts and Varied Seafloor Terrain:

• The seafloor is not flat but features varied terrain, including mountains larger than Mount Olympus in Greece and long mountain ranges called seamounts.
• New seamounts are continually discovered, leading to the discovery of new species and habitats.

6. Newly Discovered Marine Species and Adaptations:

• Scientists are constantly discovering new marine species, with 800 new species found in one study last year.
• One example is the "guitar shark," which resembles a guitar with fins.
• Many deep-sea creatures have unusual appearances due to adaptations to their environment, such as transparency for avoiding predators, large eyes for capturing more light, and large stomachs for storing food.
• The color red is difficult to see in the deep ocean, so many species are dark red to appear invisible to predators.

7. Importance of Ocean Research for Climate Change and Resource Management:

• Oceans produce 50% of the world's oxygen and play a crucial role in climate change by absorbing 90% of the excess heat from burning fossil fuels.
• The biological/biochemical carbon cycle involves tiny creatures absorbing carbon and transporting it to the deep ocean, which is vital for protecting the planet.
• Understanding this carbon cycle is essential for mitigating climate change.
• The deep ocean contains valuable minerals, leading to interest in deep-sea mining.

8. Deep Sea Mining:

• Deep-sea mining is a controversial area due to the potential damage it could cause to the environment.
• As technology advances and demand for minerals increases, there is growing interest in mining the deep ocean.
• There are significant questions about the environmental impact of deep-sea mining and whether it should be allowed.

9. Notable Quotes:

• Georgina Rannard: "So my favourite fact is, actually, it's not about an amazing animal or a strange habitat, but it's that 50% of the oxygen we get on Earth comes from the oceans."
• Georgina Rannard: "...you think about the sea floor and floor implies flat. You don't always think of it as being this incredibly varied terrain, but it's as varied or even more so than land."

10. Synthesis/Conclusion:

Ocean exploration is a challenging but crucial endeavor. The extreme conditions of the deep sea, including immense pressure, darkness, and cold temperatures, require advanced technology and innovative approaches. Despite these challenges, ongoing research continues to reveal new species, unique geological features, and critical insights into the ocean's role in climate regulation. The discovery of "dark oxygen" and the exploration of seamounts highlight the potential for groundbreaking findings. However, the increasing interest in deep-sea mining raises concerns about environmental impacts, emphasizing the need for careful consideration and sustainable practices. Ultimately, understanding the deep ocean is essential for protecting the planet and managing its resources responsibly.