Living within our limits: Exploring Planetary Boundaries

Sustainable Infrastructure - Principle 1. Environmental Sustainability - Living Within Our Planet's Limits 

This post explores the concept of planetary boundaries, the first principle of sustainable infrastructure (see the introduction to this series inspired by the book “Sustainable Infrastructure: Principles into Practice”).

Environmental Capacity:   

Sustainable development has often been described as the "triple bottom line" of financial (or economic), social and environmental impacts, with a lovely Venn diagram showing these three ideas working in harmony. However, this doesn't reflect the relative importance of the three elements: cost or economic benefits are usually considered to be the main driver for development, but there's little point having lots of money if the result is destroying the capacity of our one and only planet to support life! 

A better model is provided by Forum for the Future's Five Capitals, showing the environment (natural capital) as the circle surrounding all that happens within (social capital, financial capital, goods and services).

Environmental limits need to be regarded as a hard constraint that cannot be exceeded, rather than a "nice to have" or a question of simply legal compliance around the "hard" business of providing an essential service such as water supplies for a reasonable cost. Here's an engineer's explanation: I design foundations so that the loads applied to the ground don't exceed the soil's bearing capacity with a reasonable factor of safety to prevent failure (this accounts for uncertainties and the potential for accidental overloads). If the soil is not strong enough, I only have two choices if I don't want my building to fall down: increase the carrying capacity of the soil (difficult) or reduce the load/change how it is applied so that it does not exceed the capacity. 

We need to apply the same principle to ensure we stay within planetary limits: we cannot easily increase the carrying capacity because we're already using so much of it, but we can reduce the load so that we stay safely within that capacity. But how do we define what the safe boundaries are? 

Understanding Planetary Boundaries
Johan Rockström and colleagues from the Stockholm Resilience Centre have published research into planetary boundaries which has gained widespread scientific support and stimulated much debate. You can listen to an excellent TED Talk by Rockström here, which explains the research in just twenty minutes. It consists of nine planetary systems upon which all life depends, with a calculation of the threshold level (boundary) for each. These are hard constraints: remaining within these boundaries gives the possibility of a ‘safe operating space for humanity’, whilst transgressing them could lead to abrupt and disastrous environmental change. 

The image below shows the nine systems with the "safe space" in green: climate change, biodiversity loss and nitrogen production have already exceeded the safe zone by a considerable margin. Living within our limits means we need to change our ways, and our infrastructure!

Planetary Boundaries (c) Stockholm Resilience Centre

Make Wealth History (one of my favourite blogs) has written a whole series examining each of the nine systems in more depth - follow the links to read more:

1. Climate Change
2. Ocean acidification
3. Ozone depletion (the "hole in the ozone layer", which is now recovering slowly)
4. Nitrogen and phosphorus cycles (artificial production of nitrates and phosphates causes algal blooms and dead zones)
5. Freshwater availability
6. Land (for farming, woodland and natural systems as well as human infrastructure and buildings)
7. Biodiversity loss (the fastest rate of extinctions seen on earth since the dinosaurs)
8. Atmospheric aerosols
9. Chemical pollution

Reference:

Sustainable Infrastructure: Principles into Practice, Charles Ainger and Richard Fenner, ICE Publishing, 2014

See Also:

• What is Sustainable Infrastructure? Introduction to the series
• Storms, Floods and Landslides - An Engineer's Tale of Climate Change in the UK
• If There Is No Home For Nature
• A Rocha Blog - Pushing the Boundaries