Overview of Impacts
Climate change profoundly affects ocean ecosystems through rising sea temperatures, ocean acidification, sea-level rise, and altered ocean currents. These changes disrupt marine life by stressing species, altering habitats, and shifting food webs. For instance, warmer waters lead to coral bleaching, while increased CO2 absorption acidifies seawater, harming shell-forming organisms like mollusks and corals.
Key Mechanisms
The primary mechanisms include thermal expansion and melting ice causing sea-level rise, which floods coastal habitats; acidification from dissolved CO2 that reduces carbonate availability for calcifying species; and deoxygenation in deeper waters due to warmer surface layers limiting oxygen mixing. These factors collectively reduce biodiversity and alter nutrient cycles essential for primary producers like phytoplankton.
Practical Example: Coral Reefs
Coral reefs exemplify these impacts, as seen in the Great Barrier Reef, where repeated bleaching events from elevated sea temperatures have killed over 50% of corals since 2016. This not only destroys habitats for thousands of fish and invertebrate species but also diminishes reef resilience to storms, leading to cascading effects on fisheries and coastal protection.
Broader Implications
These changes threaten global food security by reducing fish stocks that support billions of people, exacerbate coastal erosion, and contribute to feedback loops like methane release from thawing permafrost. Protecting ocean ecosystems requires reducing emissions and establishing marine protected areas to enhance resilience against ongoing climate pressures.