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Understanding Marine
Ecosystem Threats
Our oceans, which cover over 70% of the Earth, are facing unprecedented challenges. Marine ecosystems, including coral reefs, seagrass meadows, mangroves, and marshlands, are under immense pressure due to human activities. These ecosystems are critical for maintaining biodiversity, stabilizing our climate, and protecting coastal communities. However, they are rapidly disappearing. The good news is, we still have time to make a difference. By taking immediate action to reduce carbon emissions, protect marine ecosystems, and implement sustainable practices, we can help preserve these vital habitats for future generations. The health of our oceans is directly linked to the health of our planet, and it’s up to all of us to ensure that future generations inherit a thriving, vibrant marine environment.
Known as the “rainforests of the sea,” coral reefs are some of the most diverse ecosystems on Earth. But since 1998, mass coral bleaching events, caused by rising ocean temperatures, have led to the loss of nearly 50% of coral cover worldwide. The most recent mass bleaching occurred in 2024, further threatening the survival of these vital ecosystems.
Did you know that some of the world’s best carbon capturing machines aren’t trees but underwater plants? That’s right mangroves, salt marshes, and seagrass meadows are nature’s secret weapon against climate change. These coastal ecosystems absorb and store carbon dioxide (CO2) at rates much faster than tropical rainforests.
The melting of glaciers and ice sheets is causing sea levels to rise, displacing coastal communities around the world. By 2100, some low-lying island nations could become uninhabitable, and millions of people could lose their homes.
These ecosystems are essential for trapping carbon, maintaining clean water, and providing shelter for marine life. However, global seagrass coverage has decreased by almost 30% over the last century, largely due to coastal development and pollution. Mangroves, which act as powerful carbon sinks and nurseries for many marine species, are also being lost at an alarming rate, with an estimated 1-2% of mangrove forests disappearing each year.
As the concentration of CO2 in the atmosphere rises, more of it is absorbed by the ocean, leading to increased acidity. Since the Industrial Revolution, the acidity of the oceans has risen by 30%. This makes it harder for organisms like corals, shellfish, and plankton to build their calcium carbonate shells, disrupting the marine food web and threatening entire ecosystems.
Stressors on the Ocean
The ocean faces numerous stressors, many of which are the direct result of human activity:
Rising ocean temperatures are causing thermal stress to marine life, leading to coral bleaching, species displacement, and altered reproductive cycles. The Great Barrier Reef, for example, has lost over half of its coral cover since 1985 due to recurring heat waves.
Unsustainable fishing practices have led to the collapse of major fish stocks. The Atlantic cod population, for instance, declined by nearly 95% by the 1990s, while global shark populations have dropped by over 70% due to bycatch and finning practices.
Carbon Emissions Timeline
In 1856, Eunice Foote first identified CO2’s role in warming the atmosphere. By the 1890s, Svante Arrhenius calculated the potential for fossil fuels to cause climate change. In the 1960s, Charles David Keeling provided critical data confirming rising CO2 levels. By the 1980s, Exxon scientists internally acknowledged the risks of fossil fuel emissions, though the company publicly denied them. In 2023, atmospheric CO2 levels hit a record 419 ppm, the highest in human history.
Pollution from plastic waste, chemical runoff, and habitat destruction through unsustainable fishing practices continue to threaten marine biodiversity. An estimated 8 million metric tons of plastic enter the ocean each year, leading to vast garbage patches such as the Great Pacific Garbage Patch, which has now grown larger than Texas.
