How can the essential needs of the growing human population be met without breaking the Earth’s already-stretched life-support system? This is the question I set myself to answer with my new book, ‘One Planet’ Cities: Sustaining Humanity within Planetary Limits.

Cover of the book One Planet Cities Sustaining Humanity Within Planetary Limits by David Thorpe

It is linked to my new campaign for cities to declare an ambition to reduce their ecological footprint, beginning in Wales, as a response to the twinned climate and extinction emergencies, which I am running with the Global Footprint Network.

It is also a key textbook for a new postgraduate certificate in #OnePlanet Governance at the University of Wales Trinity St David, that civil servants and other students can take as distance learning from anywhere in the world, and gain CPD points. I want to train the next generation of civic leaders in how to save the world.

Although I started my work before Kate Raworth’s Doughnut Economics came out, it builds on it and the work of the Global Footprint Network, whose president, Matthis Wackernagel, was extremely helpful during its writing.

It is based on interviews with a great many urban leaders around the world and webinars with them that I have conducted during my time as curator of the sustainable cities collective web forum, as well as much supplementary research.

It’s also a follow-up to my previous book The One Planet Life, which is a manual for what individuals and households can do to reduce their ecological footprint and live lightly on the earth. At the end of that book there are twenty case studies, the last ones being set in cities.

Contraction and convergence

Four out of five people are predicted to be urban dwellers by 2080. No country or city in the world now meets the needs of its citizens In a truly sustainable fashion (within Raworth’s doughnut).

‘One Planet’ Cities proposes a pathway to this genuine sustainability for cities and neighborhoods, using an approach based on ‘contraction and convergence’.

The new book examines all aspects of modern society from food provision to neighbourhood design, via industry, the circular economy, energy and transport through the critical lens of the ecological footprint and relevant supporting international standards and indicators.

There are recommendations on managing supply chains and impacts, how the transition to a world within limits might be financed, and a deep examination of the Welsh Government’s pioneering efforts follow.

It discusses how the dystopic stories we tell ourselves about the future can influence the future we make and concludes with an imagined vision of what a genuinely sustainable future might be like, based on the examples in the book, and an appeal for ‘one planeteers’ everywhere to step up to the challenge.

What would setting a target to be a ‘one planet’ city mean?

It means adopting a framework for working over time so that all activities over which a city has power & influence combine together to reduce its ecological footprint (which includes carbon and biocapacity) to a measurably sustainable level. The time period is defined. The main tools are shifts in collective awareness and in the way all money is spent. The objective is to address the combined climate, resource and extinction emergencies at the same time with win-win-win solutions to create a flagship healthy, successful and resilient city.

The 6-step path towards One Planet a city

1. Obtain community buy-in and awareness-raising.
2. Decide which standards and goals to use.
3. Determine the baseline – the current situation of biocapacity and resource use.
4. Set targets to ratchet down consumption and boost biocapacity for each sector over realistic timescales (e.g. 5-year intervals up to 2030 then 2050).
5. Set in place ways to measure them.
6. Keep checking and refining.

The basic ‘One Planet’ a city requirements

  1. An aim to reduce the ecological footprint to ‘one planet’ by (say, 2050) would become an underlying principle of all planning and policy as a verifiable regenerative strategy.

  2. That the same set of social and environmental criteria should be used to assess all planning applications and procurements (i.e. a reduction of ecological footprint and increase in biocapacity, step-changing incrementally over time to the level currently applied to One Planet Developments in the open countryside  in Wales under TAN6).

  3. The criteria should be informed by appropriate indicators including lifecycle and ecological footprint analysis, using the simple NPV+ tool which allows you to compare all potential and actual projects for their impacts and benefits.

  4. Official policy would support all areas and sectors to become more productive and more biodiverse – regenerative. E.g. supporting more food growing in the city.

  5. Reduction of excessive consumption by a shift to a closed loop economy using procurement tools and believing that meeting basic needs is sufficient for everybody.

How spending bodies would proceed

Every project initiated by public bodies would be evaluated relative to the overall goal as follows:

  • Where does a city want to be resource-wise in 2030 and 2050 to position itself for success?

  • What Ecological Footprint reduction does this imply? (relative to the baseline survey)

  • What is the financial budget of the city for projects over the time period (for instance to 2030 or 2050)?

  • By dividing the reduction by the expected budget, one gets a minimal performance standard for all projects.

  • Every project that does not beat this benchmark becomes a liability and should be avoided. Favour the best performing projects and learn from them.

This implies 2 questions about all spending (in line with WBFGA)

To make sure ALL of a city’s investments are effective in helping to achieve the defined objective they would need to pass two evaluations:

  1. Is the investment producing a positive financial return (ROI)? If not, the project will not be replicable. The higher the ROI the faster it can be scaled.

  2. Is the investment advancing resource security sufficiently rapidly? If not, a city will not be prepared for the future we anticipate. (Resource security is defined by biocapacity, population, resource (including carbon) flows).

Tools to help: 1. Ecological Footprint accounting

  • Provides a biological view & joins all the human pressures – water, climate, biodiversity, food, energy, etc. This allows us to solve them all together.
  • Ecological Footprint results are understandable by ordinary people (unlike carbon).
  • Makes the economic self-interest clear and obvious. It emphasizes resource security.
  • It allows policy analysts to identify which options reduce the resource dependence of an economy and by how much.
  • Sustainable investments that satisfy investors need to meet both the resource and the fiscal criteria.

 To achieve this use: 2. The Net Present Value+ tool

  • Expands on classical NPV. See:
  • It compares different scenarios for a given spend.
  • Can help you evaluate how much the spending benefits social, financial and environmental criteria.
  • It also clarifies what the assumed future is within which the spend has to operate.
  • Ensures all the relevant costs & benefits are counted within the WBFGA’s 5 ways of working.


We can offer a city baseline evaluation and capacity building which can be applied to any supply/consumption chain & procurement life-cycle analysis strategy. A city assessment as baseline is typically around £50,000. a city would get a Consumption Land Use Matrix (measuring biocapacity vs resource use) it can regularly update itself. The result would be the beginning of win-win strategy. A city would have nothing to lose and everything to gain.