The planetary boundary concept defines a safe operating zone for earth's environment to function (Rockstrom et al.
2009) and to maintain optimum living conditions for humanity to thrive. The planetary boundary concept outlines nine of earths processes and their thresholds that if transgressed can result in a change of earths environment into a new state. The current state of the earth's environment has been stable for the past 10,000 years (Rockstrom et al. 2009), however since the rise in industry the presence of human induced environmental change has also increased.
The introduction of a new era of earth's environmental has been caused by the destabilization of earth's current landscape and the production of an environment that is relatively less hospitable for human development (Steffen et al. 2015).
Nine of earth's system processes including climate change; rate of biodiversity loss (terrestrial and marine); interference with the nitrogen and phosphorus cycles; stratospheric ozone depletion; ocean acidification; global fresh-water use; change in land use; chemical pollution; and atmospheric aerosol loading all have been identified as pivotal processes in the earth's environment.
The processes have typically been quantified and a zone of safe operating applied respectively. This zone indicates the quantified levels in which the earth's processes may remain functioning to maintain the current state. This safe zone is limited by its planetary boundary. If this boundary is transgressed the quantified processes pass into a zone of uncertainty followed by a higher risk zone beyond uncertainty (Steffen et al. 2015). The earth processes all have parameters in which they are measured and are based typically on their pre-industrial revolution values (Rockstrom et al. 2009). For the processes where there is already an accumulation of research the quantitative boundaries have been set, however some of the processes have an effect of earths environment in a way in which it cannot be easily tracked and therefore boundaries are not as easily to quantify and limit (Steffen et al. 2015). It can only be estimated what will happen to the earths processes over time if the thresholds are transgressed, however the earths systems are at higher risk of a change in state if they exceed the safe operating zone and move past the boundary into the zone of uncertainty (Steffen et al. 2015).
Planetary boundaries are the large-scale guidelines developed to attempt to preserve the current state of the earth's environment attempting not to push it to a point of no return. A planetary boundary is set in accordance to a number of factors. The boundary position is related to how much risk of change in state of the environment society deems as acceptable. Furthermore it is also related to the societal acceptance and tolerance in the changing of the environment from communities. For example, the acceptance of irreversible UV-B radiation effects on societies health if the boundaries is exceeded (Rockstorm et al. 2009b). Boundaries also need to be time sensitive, where society has time to effect the decisions made in the present, however also be able to influence sustainability over time (Rochström et al. 2009b). Boundaries have to be measured using different variables or parameters therefore guidelines were also set to ensure they could be quantified effectively. However for the processes of atmospheric aerosol loading and chemical pollution the boundaries are yet to be quantitated as the control variables are either not yet defined or are unable to be consistently
and effectively measured. It is therefore evident that more research is needed into these areas for boundaries to be set and effectively measured and a safe functioning zone maintained.
A safe operating space is one that is well clear of the planetary boundary and allows for the regulation of earths systems. The zones all are measured differently yet are still interdependent (Rochström et al. 2009b). The boundaries each are measured using different parameters or control variables yet they affect each other. If one of the boundaries are transgressed the safe level of another boundary may be influenced (Rochström et al. 2009b), that is an alternate boundary man decrease and the projected safe operating space could be declined. For example increases in biodiversity loss can impact several of the other boundaries including climate change, freshwater use and land use; likewise these processes can be related back to biodiversity loss. For instance a change in land use from rural to urban may include deforestation and loss of flora and fauna on a large scale, therefore contributing to biodiversity loss. Three boundaries have already been transgressed and it is unknown for how long these levels can continue before evident and irreversible damage is done to the earth's environment, which may react in a way that is unsafe for human life (Rochtröm et al. 2009b).
Planetary boundaries are a way in which humanity can ensure their environment is able to thrive and exist in a safe and effective state. This is done through applying safe operating zones that if maintained can foster the sustained working of earth's current processes and environmental state and lower the risk of a break down of the processes. This concept has seen to be a good starting point for the preservation of the earth's intricate and delicate ecosystems. Much more research is required to fully develop the concept and ensure the preservation of earths functioning to facilitate human life. Research into the current and expected damage is needed to quantify how long the boundaries can be transgressed before damage cannot be undone and before the effects are apparent. Additionally in response a change in human activities are needed to fulfill these zones and prolong the healthy ecosystems on earth. Therefore it is evident that the framework set out through the planetary boundary concept is a pivotal tool in the preservation of earth's biophysical processes. If these boundaries are quantified and action is taken to maintain processes within them then the earth can continue to function in a zone that is safe for humanity now and in the future.