How climate change impacts the ocean

The ocean absorbs a huge part of climate change’s impact—it takes in most of the excess heat from greenhouse gases and a large share of carbon emissions. But that also means it’s bearing the cost: marine ecosystems are seeing serious changes, and many species are under threat. Major Impacts on the Ocean • Rising sea levels — Ice melt and warmer water expanding are increasing sea levels significantly. The amount of rise has accelerated in recent decades. • Marine heatwaves — Unusual spikes in ocean temperature, lasting days to months, harming marine life and damaging ecosystems like coral reefs. • Ocean acidification — CO₂ absorption changes water chemistry, making it harder for shell-forming organisms and coral to build skeletons and reefs. • Biodiversity loss — Many species are losing habitat, struggling to adapt, or facing population decline due to combined stressors (temperature change, acidification, habitat loss). • Changes in migratory patterns — Marine species are shifting their ranges, altering marine food webs and impacting fishing communities. Effects on People & Coastal Communities • Coastal erosion & flooding — Rising seas and more severe storms threaten homes, infrastructure, and livelihoods in low-lying areas. • Livelihood impacts — Many communities depend on fisheries, marine tourism, or coastal ecosystems. As ocean changes disrupt species distribution and ecosystem health, incomes and food sources are at risk. Why Oceans Matter to the Climate • Carbon sink function — Oceans absorb both heat and carbon, which helps slow atmospheric warming. But the higher the load, the more stressed their systems become. • Ecosystem services — Healthy marine ecosystems (reefs, mangroves, seagrass beds) support biodiversity, protect coasts, and provide food and income. What We Can Do / Hope For • Advocacy & policy — Support for marine protected areas, international treaties and policies that protect ocean health. • Conservation efforts — Restoring coral reefs, protecting blue carbon habitats such as mangroves and seagrasses, and reducing pollution. • Individual action — Reducing carbon footprint, supporting sustainable seafood and reducing plastic waste, promoting awareness of ocean health.