UN-SDG 14: Life Below Water

A Planetary Problem with a Social Toll Ocean acidification, driven by anthropogenic carbon dioxide emissions, represents a critical planetary boundary within Kate Raworth’s Doughnut Economics framework, directly linking climate change impacts to marine ecosystem health and human food security. As atmospheric CO₂ levels have risen from pre-industrial concentrations of 280 µatm to current levels exceeding 414 µatm, the ocean’s absorption of this excess carbon has fundamentally altered seawater chemistry1. This process has decreased ocean pH by approximately 0.1 units since the Industrial Revolution, with projections indicating further declines to pH 7.8 by 2100 and potentially as low as 7.45 by 23002. The concept of fish adaptation to ocean acidification sits at the intersection of planetary health and social foundations, as marine fisheries provide essential protein sources for over 3 billion people globally while supporting the livelihoods of millions in coastal communities. ...

A (Grim) History of Hollowing Out Our Home The understanding of biodiversity as a planetary boundary has developed considerably over recent decades. Scientists have progressively recognized that biological diversity represents not merely an environmental concern but a fundamental limit to human activities. This recognition began with the Stockholm Resilience Centre’s introduction of the planetary boundaries framework, which identified biodiversity (or biosphere integrity) as one of nine critical Earth system processes that maintain planetary stability1. ...

Ecological Impacts of Nitrogen and Phosphorus Runoff Eutrophication and Aquatic Dead Zones Excess nitrogen and phosphorus from fertilizers enter waterways through surface runoff and leaching, triggering eutrophication—a process where algal blooms deplete dissolved oxygen, creating hypoxic “dead zones” incapable of supporting marine life12. The scale of this crisis is particularly evident in the Gulf of Mexico, where a massive 6,334-square-mile dead zone persists due to Midwestern agricultural runoff. This environmental catastrophe has decimated local fishing industries, reducing shrimp catches by 40% and destabilizing coastal economies that have relied on these waters for generations34. ...

Unmasking Maritime Pollution’s Depths The global shipping industry, while vital for international trade and economic growth, significantly contributes to chemical pollution in our oceans and atmosphere. This pollution extends far beyond the visible oil spills that often capture headlines. It encompasses a complex mixture of air pollutants, greenhouse gases, and water contaminants, with far-reaching consequences for both environmental and human health. ...

To truly understand the complexities of ocean acidification, it’s essential to delve into its underlying chemical mechanisms. When seawater absorbs atmospheric CO2, a gas that is being emitted at alarming rates due to human activities, it triggers a cascade of chemical reactions that ultimately increase hydrogen ion concentration and subsequently lower the water’s pH, making it more acidic.12 This intricate chemical process simultaneously reduces carbonate ion availability, a critical building block. This reduction proves particularly devastating for shell-building organisms such as oysters, clams, and mussels, which rely on these carbonate ions for survival and the development of their protective shells.34 ...