Achieving Planetary Boundaries Requires Collaborative Solutions

11,700 years ago, Earth emerged from the last ice age and began a period of stable climate known as the Holocene. Humans have inhabited this time period, which has been beneficial to us in many ways. We have advanced in agriculture, seen the rise of civilizations, and shifted our focus to more nuanced pursuits beyond basic survival.

A new study questions how far away Earth is from departing from its current state of relative security. According to the publication, human actions have surpassed six out of nine “planetary boundaries” which indicate the point at which the planet is at a higher risk of entering an unstable state.

This does not necessarily indicate the imminent end. Katherine Richardson, an Earth systems scientist from the University of Copenhagen and lead author of the study, believes that there is still a future despite being a mother and grandmother. However, it is crucial for policymakers to take steps to reverse the current trends. Richardson emphasized the need for us to actively manage our relationship with the global environment for our own well-being.

Setting Boundaries

In 2009, Richardson and her team measured the traits of Earth’s systems that may impact the stability of the environment, such as high levels of atmospheric carbon dioxide, nutrient pollution, and depletion of natural environments. They identified limits beyond which these traits would become concerning. At that point, the planet had surpassed three of these boundaries.

In 2015, the amount increased to four. Currently, six limits have been exceeded. Richardson expressed, “This cannot persist.”

According to Jon Wang, an Earth system scientist from the University of Utah who was not part of the study, determining a boundary can be difficult in some cases. For instance, the research team suggested that the goal should be to completely eradicate “novel entities” – pollutants like plastics and nuclear waste that would not naturally exist on Earth without human influence. However, Wang expressed concern about this approach, as the impact of these substances on Earth’s ecosystems is not fully understood, possibly making the boundary too restrictive. Wang stated, “That was the one I struggled with.”

According to Richardson, the boundaries should be viewed as protective measures rather than specific limits. She compares them to blood pressure, where a reading above 120 over 80 may not necessarily indicate health issues, but it is outside the ideal range and poses risks. Similarly, exceeding one or more boundaries does not automatically mean that the world will collapse, but it does suggest a potential for human activities to alter overall Earth conditions. This could potentially lead to a point where the planet can no longer sustain modern civilizations.

Interconnected Processes

Richardson and her colleagues argue that ecological processes are interconnected and should be viewed as a whole. Wang illustrates this concept by pointing out that while increasing levels of carbon dioxide can worsen climate change and ocean acidification, it may also have a positive impact on plant growth, albeit temporarily.

Synergistic efforts can lead to simpler solutions in certain situations, as policymakers can implement strategies that have multiple positive impacts on the Earth. For instance, reducing deforestation not only helps combat climate change, but also preserves ecosystems. However, this also highlights the potential negative consequences of addressing issues in isolation, as noted by Bob Howarth, an Earth system scientist from Cornell University who was not involved in the study.

Howarth referenced no-till farming as an example. This agricultural technique involves planting crops without disturbing the soil, which leads to a decrease in carbon release from microbes and promotes soil health. However, there are circumstances where this practice may decrease the soil’s ability to retain nitrogen, resulting in more of the nutrient being carried into rivers. Alternatively, transitioning to crops that have longer lifecycles and develop extensive root systems could have a positive impact on the soil without causing nutrient pollution.

Howarth stated that we must approach the issues comprehensively and consider all possible solutions.

Reasons for Hope

Richardson stated that if Earth stays on its current path, there is a possibility that humans will be forced to leave certain areas of the planet due to extreme heat, loss of entire ecosystems, and frequent destructive storms. However, Richardson remains hopeful that this scenario can be avoided through the power of knowledge.

In previous times, communities have utilized scientific understanding to counteract environmental damage. For instance, one aspect known as planetary boundaries, specifically stratospheric ozone depletion, exceeded its limit in the 1990s but has since returned to a safe level. Similarly, the levels of aerosol pollutants, like sulfur dioxide, have been decreasing since the 1980s due to various factors, such as power plants implementing filters in their smokestacks and individuals in certain regions transitioning away from cooking over open fires.

The latest report may cause concern among numerous individuals. According to Howarth, this fear should serve as motivation to take action, as many of these trends can still be reversed.

—Saima May Sidik (@saimamaysidik), Science Writer

Reference: Sidik, S. M. (2023). Finding effective solutions to surpass planetary boundaries. Eos, 104. Retrieved from https://doi.org/10.1029/2023EO230379. Published on October 6, 2023.

Text © 2023. The authors. CC BY-NC-ND 3.0

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