VIZAG: The Earth’s ability to support large-scale human societies is in danger of expiring because of our continued reliance on environmentally destructive practices. Holding up a mirror to the human race, a new study says we are doing everything and anything but the right thing.
The study, ‘Earth beyond six of nine planetary boundaries,’ published in Science Advances, says we have already transgressed six of the nine ‘planetary boundaries’, pushing Earth’s environment to the brink of destruction. The six boundaries are climate change, biosphere integrity (genetic diversity and energy available to ecosystems), land system change, freshwater change (changes across the entire water cycle over land), biogeochemical flows (nutrient cycles), and novel entities (microplastics, endocrine disruptors, and organic pollutants).
What are planetary boundaries? Think of planetary boundaries as Earth’s health indicators. These nine boundaries aim to keep Earth in a state similar to the past 12,000 years—a time of relative stability and warmth named the ‘Holocene epoch’. These boundaries are like safety limits for our planet’s health, and when they’re crossed, it’s a cause for concern.
The study was conducted by a team of 29 scientists representing eight countries. Its findings serve as an update to the planetary boundaries framework, which was initially introduced in 2009. The recent study assigns specific numerical values to each of the nine boundaries, offering a concrete measure of by how much we have exceeded these limits.
1 Climate Change
One of the transgressed boundaries is climate change driven by the atmospheric carbon dioxide (CO2) concentration. The established safe limit for CO2 was set at 350 parts per million (ppm). However, the study highlights the grim reality that this limit was surpassed as far back as 1988. Currently, CO2 levels stand at a staggering 417 ppm, leading to profound climate change, including global warming.
2 Land System Change
The goal was to maintain 75% of the planet’s original forest cover. Regrettably, the current estimate falls far short at 60%. These changes to land systems have profound consequences, disrupting ecosystems and threatening biodiversity.
3 Biosphere Integrity
This boundary was defined to ensure that the extinction rate remains below 10 per million species-years. Tragically, the actual rate now exceeds a staggering 100 extinctions per million species-years. This poses a severe threat to countless plant and animal species, jeopardising the intricate balance of our ecosystems.
4 Freshwater Change
Both blue (surface and groundwater) and green (water available for plants) water resources have surpassed their established boundaries. Changes in the water cycle over land have had detrimental effects on ecosystems, disrupting the delicate balance of water availability for plants and aquatic life.
5 Biogeochemical Flows
The flows, particularly of phosphorus and nitrogen, have been exceeded. They have far-reaching implications, including detrimental effects on biodiversity and water quality. It disrupts the natural balance of nutrient cycles, affecting ecosystems on land and in water.
6 Novel Entities
They encompass substances like microplastics, endocrine disruptors and organic pollutants. The planetary boundary for novel entities was initially set at zero, emphasising their absence in Earth’s natural systems. This boundary has been transgressed. Risks associated with this transgression include stratospheric ozone depletion, aerosol loading, and ocean acidification, each carrying its own set of consequences.
Thankfully, the other three boundaries - stratospheric ozone depletion, atmospheric aerosol loading and ocean acidification - are currently within their defined limits. “Ozone depletion is showing positive progress, largely due to the 1987 Montreal Protocol and the reduction in chlorofluorocarbon (CFC) use. However, the other two boundaries, although currently within their limits, are moving close to exceeding those limits at a rapid pace,” it noted. What’s the big picture? The study tells us that we can’t just look at these problems one by one.
They’re all connected, and when they pile up, it’s bad news for the planet. “Currently, anthropogenic perturbations of the global environment are primarily addressed as if they were separate issues, e.g., climate change, biodiversity loss or pollution. Planetary boundaries bring a scientific understanding of anthropogenic global environmental impacts into a framework that calls for considering the state of the Earth system as a whole,” the study stressed.