An Analysis of the Planetary Boundaries Theory

Human impacts on the Earth have only been studied for the past few decades and until very recently scientists didn't quite understand many of the connections between planetary processes and cycles. Johan Rockström is one of the main scientists who suggested the criticality of planetary boundaries and "tipping points." Rockström explains that planetary boundaries are systemic processes at a planetary scale and aggregated processes from local/regional scales. The nine planetary boundaries include climate change, ocean acidification, stratospheric ozone, global phosphorus and nitrogen cycles, atmospheric aerosol loading, freshwater use, land use change, biodiversity loss, and chemical pollution. Rockström states that each process has a quantitative threshold that will transition to a non-linear function after reaching that specific point. If a process transitions to a non-linear function, the results could be catastrophic for humanity. Additionally, each planetary boundary has the ability to impact other planetary boundaries, such as in the case of land degradation impacting climate change. While there are nine planetary boundaries, we have already crossed three of them, including climate change, rate of biodiversity loss, and the nitrogen cycle. We also don't know the proposed boundaries, current statuses, and pre-industrial values of atmospheric aerosol loading and chemical pollution (Rockström et al., 2009).

Although the planetary boundaries and tipping points concept offer a basis for action against reaching the proposed boundary and feeling the possibly catastrophic events, it's important to weigh the strengths and weaknesses of this concept.

Strengths and Weaknesses:

There are numerous strengths and weaknesses to the planetary boundaries and tipping points concept that must be taken into account when assessing it. One weakness of the concept, as explained by Molden (2009), is that it essentially overlooks local conditions, specifically in the case of global freshwater use. Molden further explains that Rockström's proposed boundary of 4,000 may be too high. Molina (2009), another commentator on Rockström's theory, specifically states that in the case of stratospheric ozone depletion Rockström's proposed boundary may be flexible and even lower than the actual tipping point. The current crossed planetary boundary of climate change also brings about suggested weaknesses in the planetary boundary idea. Allen (2009) states that one of the main weaknesses of the planetary boundaries theory is that the concept itself suggests that the atmosphere isn't exhaustible and that we can pursue our output as long as it's below the proposed boundary.

Allen adds that emission reductions are needed urgently to pull us away from reaching catastrophic outcomes at an exponential rate. Bass (2009) proposes that another weakness of the planetary boundaries theory is that some of the Earth-system processes are not specific enough or should refer to other issues that are encompassed by the broader process. For example, Bass says that land use degradation/change in land use should specifically regard soil, including putting limits on soil use and soil degradation because it's a better indicator of terrestrial health than simply "change in land use." A final proposed weakness directly assesses the problem of setting boundaries. Schlesinger (2009) suggests that setting quantitative boundary only encourages anthropogenic degradation as long as it's below a certain point. Schlesinger, like Allen, states that these boundaries shouldn't be considered inexhaustible as long as we stay below a certain point. Instead, we should consider reductions as opposed to just staying right below the proposed boundary for each Earth-system process.

Although there are numerous weaknesses of the planetary boundaries and tipping points theory, there are still strengths that should be taken into account. One of the main strengths is that it helps bring awareness to an issue, specifically that these tipping points can lead to a non-linear transition (Lenton et al., 2009). Additionally, putting a numeric value also has strengths. It can make creating and implementing policy easier on national and international levels. Without numeric values placed on boundaries, it's incredibly harder for policy that helps control and prevent our progression towards that number to be created. If we're able to say 350 ppm is the planetary boundary for carbon emissions, it's much easier to work to get below a specific level. The planetary boundaries concept also encourages further research into these boundaries in order to find a specific proposed level that we should not cross. Further research can only be helpful to our current situation and bring about more awareness to numerous environmental issues.

Conclusion:

There are numerous strengths and weaknesses to Rockström's proposed planetary boundaries and tipping points theory. Criticisms and proposed weaknesses of the theory include it not being specific enough or not focusing on more important processes, assumptions that these processes are not exhaustible and that if we stay below a certain level then we can continue what we're doing, and if these numeric values on the proposed boundaries are accurate or if there is flexibility in the numbers. While these are all very valid weaknesses of the theory, there are still numerous strengths that should be acknowledged as well. The concept brings light to the growing environmental problems and suggests that these processes are linked in extremely complex ways. It also has the ability to encourage policy-making since this is often based on actual numbers and that numeric values make it more likely for policy to be created and implemented on numerous levels. Finally, it's also important to realize that continued research on the concept of planetary boundaries and tipping points will only aid us further in our understanding of Earth-system processes and bring further awareness to these seemingly-infinite issues.

Bibliography

Heffernan, O. (2009). Planetary boundaries (commentary). Nature.com: Climate Feedback, the climate change blog. Retrieved from http://blogs.nature.com/climatefeedback/2009/09/planetary_boundaries.html

Lenton, T. M., et al. (2009). Tipping elements in the Earth's climate system. Proceedings of the National Academy of Sciences (PNAS), 105(6), 1786-1793.

Rockström, J., et al. (2009). Planetary Boundaries: Exploring the Safe Operating Space for Humanity. Ecology and Society, 14(2), 1-32.

Rockström, J., et al. (2009) A safe operating space for humanity (summary). Nature, 461, 472-475.