The oceans are often called the “lungs of the Earth” because they produce at least 50% of the oxygen we breathe, primarily through tiny photosynthetic organisms called phytoplankton—microscopic plants, algae, and bacteria drifting near the ocean surface[1][2][5][8]. Some species, like the bacteria Prochlorococcus, alone produce up to 20% of the oxygen in the entire biosphere, surpassing even all tropical rainforests combined[1][2].
The Ocean’s Vital Role in Oxygen Production and Climate Regulation
Phytoplankton live mostly in the top 200 meters of the ocean where sunlight penetrates, enabling photosynthesis. Through this process, they convert carbon dioxide into oxygen, sustaining marine life and contributing massively to Earth’s atmosphere[2][5]. The ocean also acts as the largest active carbon sink, absorbing about 30% of human-generated CO₂ emissions and storing vast amounts of carbon in deep-sea sediments[7][8].
Current Threats to Phytoplankton and Ocean Health
Despite their crucial role, phytoplankton populations are already under severe stress from multiple human-driven factors:
– Plastic Pollution: Microplastics and larger debris disrupt phytoplankton growth by altering light penetration and releasing toxic chemicals into the water[4].
– Radiation from Fukushima: Radioactive contaminants released into the Pacific Ocean after the 2011 Fukushima nuclear disaster have raised concerns about impacts on marine microorganisms, including phytoplankton, though research is ongoing.
– Ocean Acidification: Increased CO₂ absorption lowers ocean pH, affecting phytoplankton physiology and reproduction, and disrupting marine food webs[4].
– Warming Waters and Deoxygenation: Rising ocean temperatures reduce oxygen solubility and disrupt circulation, leading to expanding “oxygen minimum zones” where marine life struggles to survive[6].
How Deep-Sea Mining Could Exacerbate These Problems
Mining the ocean floor for minerals like polymetallic nodules threatens to destroy fragile seafloor ecosystems that support microbial communities and marine biodiversity essential for oxygen production and nutrient cycling. The physical disturbance from mining equipment and sediment plumes can:
– Smother phytoplankton and other organisms by increasing water turbidity and blocking sunlight.
– Disrupt microbial processes critical for carbon sequestration and oxygen generation.
– Release stored carbon from sediments, potentially increasing greenhouse gases.
– Cause long-lasting damage, as deep-sea ecosystems recover very slowly—sometimes taking decades or centuries.
The Risk to Earth’s “Lungs”
Given that the ocean supplies roughly half of the planet’s oxygen, any significant disruption to phytoplankton or oceanic microbial life could reduce oxygen production and destabilize the climate system. Already, oxygen levels in some ocean regions have dropped by over 15%, with “dead zones” expanding due to eutrophication and warming waters[1][6].
Conclusion
Deep-sea mining poses a serious risk to the ocean’s ability to function as Earth’s lungs. Coupled with existing stresses from pollution, radiation, acidification, and climate change, mining could push marine ecosystems beyond a tipping point, threatening oxygen supply, biodiversity, and global climate regulation.
Protecting these vital ocean systems is essential—not only for marine life but for the survival of humanity itself.
Sources:
[1] NOAA Ocean Service
[2] Woods Hole Oceanographic Institution
[5] EarthSky
[6] Yale Environment 360
[7] Woods Hole Oceanographic Institution
[8] UN Climate Change
Deep Sea Conservation Coalition (paraphrased from general knowledge)
Read More
[1] https://oceanservice.noaa.gov/facts/ocean-oxygen.html
[2] https://www.whoi.edu/know-your-ocean/did-you-know/does-the-ocean-produce-oxygen/
[3] https://ugc.berkeley.edu/background-content/oxygen-levels/
[5] https://earthsky.org/earth/how-much-do-oceans-add-to-worlds-oxygen/
[6] https://e360.yale.edu/features/as-ocean-oxygen-levels-dip-fish-face-an-uncertain-future
[7] https://www.whoi.edu/know-your-ocean/did-you-know/why-is-the-ocean-vital-for-our-survival/
[8] https://www.un.org/en/climatechange/science/climate-issues/ocean