UN-SDG 13: Climate Action

Understanding Stratospheric Ozone and Its Vulnerability The stratospheric ozone layer, situated approximately 12 to 30 miles above Earth’s surface, plays a crucial protective role by absorbing harmful ultraviolet (UV) radiation from the sun12. This atmospheric shield prevents dangerous levels of UV radiation from reaching Earth’s surface, where it would otherwise cause significant harm to humans, wildlife, and ecosystems34. Under natural conditions, ozone ($O_3$) undergoes a continuous cycle of formation and breakdown, maintaining a dynamic equilibrium. In this cycle, ozone absorbs UV radiation and breaks down ($O_3$ + UV light $\rightarrow$ O + $O_2$), but the resulting oxygen atoms can recombine to reform ozone, thus preserving the protective layer while absorbing harmful radiation56. This delicate balance, dependent on complex atmospheric chemistry, evolved over billions of years, creating conditions conducive to life on Earth’s surface42. ...

Air pollution represents one of the most significant environmental health risks globally, with wide-ranging impacts across the human lifespan. Evidence from numerous scientific studies confirms that exposure to air pollutants—particularly fine particulate matter ($PM_{2.5}$), nitrogen dioxide ($NO_2$), and ozone ($O_3$)—is associated with increased morbidity and mortality from respiratory diseases, cardiovascular conditions, adverse birth outcomes, and cognitive impairments1. Even short-term exposure to pollutant levels below many regulatory standards can cause measurable health effects. Current research indicates that air pollution is responsible for approximately 8.1 million deaths annually worldwide, making it one of the leading causes of preventable deaths1. Within the Doughnut Economics framework, air pollution represents a critical planetary boundary that, when exceeded, directly undermines the social foundation of human health. The ecological ceiling breach creates a complex challenge requiring integrated policy approaches addressing both environmental protection and health equity to create a safe and just space for humanity. ...

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. ...

The Evolving Story of Freshwater Thinking The recognition of freshwater as a finite and vulnerable resource with planetary boundaries has evolved significantly over recent decades. Historically, water was primarily viewed through a resource extraction lens, with little consideration for sustainability limits or equitable access. The emergence of environmental consciousness in the 1960s and 1970s began shifting this perspective, highlighting connections between water quality, ecosystem health, and human wellbeing. ...

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. ...