Dr Anjani Ganase looks at the planetary boundaries that humans have impacted, moving the earth to a state that may no longer be hospitable for our species.
The Holocene Epoch marks 11,700 years of recorded human history in which we thrived in a stable environment and ecology. This allowed significant human evolution and in the last 100 years, saw the advance of technology and industry. In that short time, humans have drastically altered the global environment through resource extraction and pollution of our air and waterways. Some of these conditions have become destabilized resulting in the sudden loss of biodiversity, habitats, resources and even shifting climate. Scientists have collated such environmental changes between 1950 to now, to identify the most important boundaries that should not be crossed for the sake of human survival.
The planetary boundaries framework is a science-based analysis that observes the risk associated with human activities in destabilizing the earth's system. Metrics are used to identify the boundaries, which are conservatively estimated for circumstances of transgressions with some leeway for human remediation before reaching that tipping point. There are nine major planetary boundaries that must not be exceeded for the planet to remain hospitable to life as we know it and sustain thriving human societies. Three major zones are defined: (1) the safe zone of operation; (2) the zone of uncertainty - approaching the boundary with increasing risk of destabilizing the earth systems; and (3) the zone beyond uncertainty with a high risk of destabilization. The aim of identifying such planetary boundaries and measurable targets to be maintained as sustainable development goals is a safe and stable earth and a just system for human wellbeing.
Here are the nine planetary boundaries that have been considered:
- Biosphere integrity is measured by the diversity (functional and genetic) of the planet's natural world given the understanding that such evolutionary diversity is directly connected to the environment and our survival. Over the last fifty years, human activities have resulted in more biodiversity loss with current global extinction rates ranging from 100 to 1000 extinctions per million species per year (the baseline extinction rate is one species in every one million per year). We have pushed passed the planetary boundary with respect to the rate of biodiversity loss.
- Biogeochemical flows refer to chemical pollution that exists in our waterways and oceans with a specific focus on nutrient pollution (nitrogen and phosphorus) that leaches from pastoral and agricultural lands. Other chemicals have not been investigated in such detail. Considering the concentrations of nutrients to create eutrophication and anoxic waterways, the current annual rate of nutrient input far exceeds this threshold.
- Land change system refers to changes in all terrestrial biomes - forests, savannas, etc. - across the tropical, temperate and boreal regions, that regulate climate, water an
