Since the beginning of the Anthropocene, humans have been exponentially altering the state of the earth, especially since the Industrial Revolution; the accelerating driver of global environmental change. A framework titled Planetary Boundaries was introduced in 2009 and is regularly adapted to better reflect our understanding of these human effects. This is a concept that plainly identifies and explains human effects and is rooted in the proven scientific evidence of human interference and its effects on nine (9) different realms or ‘boundaries’ affecting Earth’s systems. These boundaries include; biosphere integrity; climate change; novel entities; stratospheric ozone depletion; atmospheric aerosol loading; ocean acidification; biogeochemical flows; freshwater use and; land systems change (Rockström et al., 2009). The idea is to quantify these categories into understanding their current operating level and the level at which they are accelerating. The framework includes 2 generalized sections of how each boundary is doing which includes the safe operating space and the increasing risk space (Rockström et al., 2009). Safe operating space can be located in Figure 1 as the green space on the diagram. It is believed that so long as each section remains in a safe operating space, the planet is sure to thrive and remain stable for the foreseeable future.
The Nine Planetary Boundaries
Novel entities are the most recent change to the definition of the nine boundaries with its original title being “chemical pollutants”. It was changed to better encapsulate this type of pollution. Novel entities are synthetic organic pollutants and can include things such as heavy metals, genetically modified organisms, and pesticides (Stockholm Resilience).
Stratospheric ozone depletion is exactly as it sounds. For years we have been hearing ” there’s a hole in the ozone!”. But what does that mean? Essentially the quantity of air pollution or rather, anthropogenic ozone-depleting chemical substances, are actively thinning out this protective layer in our atmosphere at the north and south poles. This is worrying as this ozone layer is what protects us from ultraviolet rays which have damaging effects on human and ecosystem health.
Loss of biosphere integrity is essentially the loss of quantity and quality of biodiversity worldwide. In 2005 it was concluded that this is accelerating at unprecedented rates for over 50 years. The global demand for food, water, and natural resources is the main drive for this change as we are exponentially consuming more and more each year. As humans consume more, they risk irreversible damage to the biosphere and the ecosystem services that it provides.
Climate change has been a pertinent topic for global sustainability as this is rapidly changing the global climate. The documented levels of CO2 in the atmosphere have already transgressed the planetary boundary and are creeping into several Earth system thresholds, threatening irreparable damage. This has directly impacted the warming of polar regions and sea ice which is melting at exponential rates. Our loss of biodiverse carbon sinks such as rainforests and wetlands is nearing another potential tipping point. These losses directly impact climate systems and negatively influence the changing of Earth’s systems.
These CO2 emissions are also the leading cause of ocean acidification as the ocean is one of the largest carbon sinks compared to the world’s rainforests. This carbon absorption is directly linked to the warming of the oceans which in turn has a major effect on climate change. This carbon also converts into a carbonic acid which directly limits the production ability of shell and skeleton formation making it difficult for aquatic life to grow and survive resulting in less marine biodiversity.
Not only do humans affect oceans but also our natural freshwater supply. Humans have taken on the responsibility of delegating where freshwater goes and how it is being used and for years leading up have failed to account for natural water systems. This human interference affects water cycles including river flow changes and shifts in vapour flows arising from land use changes which can cause irreversible damage to global water systems. As climate change persists and humans continue to decide how these freshwater systems are to be used, it is predicted that by 2050, half a billion people will experience water stress and lack the means to access fresh potable water.
Land use change refers to human interference with natural biodiversity to delegate the use of the land for their own purposes. This is extremely detrimental as these land ecosystems, for example, wetlands, rainforests, and grasslands play an integral part in global ecosystem services. This boundary has direct links with multiple other boundaries and is a huge contributor to accelerating climate change effects by disrupting Earth’s systems.
Nitrogen and phosphorus biogeochemical flows are both heavily influenced by the global agriculture industry due to the use of these chemicals in common pesticides and herbicides. These elements are essential to plant growth, however, the overuse of these products is resulting in them not being fully taken up by the plants but instead rerouting into local, and then later global, water cycles. These local water systems can soon become oxygen-starved due to these elements and overproduce bacteria and algae due to their high saturation of nutrients. At a grander scale, these nutrients find their way into global water systems and have the potential to disrupt and displace marine life due to their inability to live in polluted areas.
Aerosol loading is the final boundary and directly affects natural climate patterns and human health. The release of atmospheric pollution changes the Earth’s natural aerosol loading which interrupts the hydrological cycle and atmospheric circulation affecting monsoon systems as well as how much solar radiation is being accepted into the atmosphere due to the disruption in cloud formation. The aerosol boundary is also a crucial element to the framework as these aerosols are critical to limit the effects of atmospheric pollution but with these pollutants persisting, the result is having nearly a million people every year die prematurely due to their effects (Stolkholm University)
Where Do We Stand on the Nine Planetary Boundaries?
According to 2022 reports, five of these nine boundaries have transgressed out of the safe operating space, these include climate change; biosphere integrity; land system change; biogeochemical flows, and most recent addition to the list; novel entities which can be seen in Figure 2. Given that more than one boundary has exceeded the safe operating space, there could be a greater risk of accelerating effects due to negative interactions among boundaries (Persson et al., 2022). This is an extremely concerning reality as it was once predicted that “transgressing one or more planetary boundaries may be deleterious or even catastrophic due to the risk of crossing thresholds that will trigger non-linear, abrupt environmental change within continental-scale to planetary-scale systems” (Rockström et al., 2009).
What can I do?
Climate change is not just one person’s issue. As a collective, we need to evaluate our habits in order to reduce our personal consumption to within planetary limits. We can do this by evaluating our daily habits as well as holding companies accountable that are not doing their part. We can better understand our own consumption patterns by seeing how large our ecological footprint is by taking the quiz here! How many planets do you need to sustain your current habits?
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