Meghan Bartles
Scientific American
Originally posted 13 September 23
Here is an excerpt:
The new study marks the second update since the 2009 paper and the first time scientists have included numerical guideposts for each boundary—a very significant development. “What is novel about this paper is: it’s the first time that all nine boundaries have been quantified,” says Rak Kim, an environmental social scientist at Utrecht University in the Netherlands, who wasn’t involved in the new study.
Since its initial presentation, the planetary boundaries model has drawn praise for presenting the various intertwined factors—beyond climate change alone—that influence Earth’s habitability. Carbon dioxide levels are included in the framework, of course, but so are biodiversity loss, chemical pollution, changes in the use of land and fresh water and the presence of the crucial elements nitrogen and phosphorus. None of these boundaries stands in isolation; for example, land use changes can affect biodiversity, and carbon dioxide affects ocean acidification, among other connections.
“It’s very easy to think about: there are eight, nine boundaries—but I think it’s a challenge to explain to people how these things interact,” says political scientist Victor Galaz of the Stockholm Resilience Center, a joint initiative of Stockholm University and the Beijer Institute of Ecological Economics at the Royal Swedish Academy of Sciences, who focuses on climate governance and wasn’t involved in the new research. “You pull on one end, and actually you’re affecting something else. And I don’t think people really understand that.”
Although the nine overall factors themselves are the same as those first identified in the 2009 paper, researchers on the projects have fine-tuned some of these boundaries’ details. “This most recent iteration has done a very nice job of fleshing out more and more data—and, more and more quantitatively, where we sit with respect to those boundaries,” says Jonathan Foley, executive director of Project Drawdown, a nonprofit organization that develops roadmaps for climate solutions. Foley was a co-author on the original 2009 paper but was not involved in the new research.
Still, the overall verdict remains the same as it was nearly 15 years ago. “It’s pretty alarming: We’re living on a planet unlike anything any humans have seen before,” Foley says. (Humans are also struggling to meet the United Nations’ 17 Sustainable Development Goals, which are designed to address environmental and societal challenges, such as hunger and gender inequality, in tandem.)
Here is my summary:
Planetary boundaries are the limits within which humanity can operate without causing irreversible damage to the Earth's ecosystems. The six boundaries that have been crossed are:
- Climate change
- Biosphere integrity
- Land use and system change
- Nitrogen and phosphorus flows
- Freshwater use
- Atmospheric aerosol loading
The study found that these boundaries have been crossed due to a combination of factors, including population growth, economic development, and unsustainable consumption patterns. The authors of the study warn that crossing these planetary boundaries could have serious consequences for human health and well-being.
The article also discusses the implications of the study's findings for policymakers and businesses. The authors argue that we need to make a fundamental shift in the way we live and produce goods and services in order to stay within the planetary boundaries. This will require investments in renewable energy, sustainable agriculture, and other technologies that can help us to decouple economic growth from environmental damage.
Overall, the article provides a sobering assessment of the state of the planet. It is clear that we need to take urgent action to address the environmental challenges that we face.
