That is when I realised that economists have not grasped a simple fact that to scientists is obvious: the size of the earth as a whole is fixed. Neither the surface nor the mass of the planet is growing or shrinking. The same is true for energy budgets: the amount absorbed by the earth is equal to the amount it radiates. The overall size of the system – the amount of water, land, air, minerals and other resources present on the planet we live on – is fixed.

While living in a steady state system – planet earth – economists still fantasise that we can ´grow´ our economies exponentially, forever.

As long as our economic system is based on chasing economic growth above all else, we are heading for environmental and economic disaster. To avoid this fate, we must switch our focus from quantitative growth to qualitative development, and set strict limits on the rate at which we consume the earth´s resources.

In such a steady state economy, the value of goods produced can still increase, for example through technological innovation or better distribution, but the physical scale of our economy must be kept at a level the planet is able to sustain.

No doubt the critics will just insist that we will go to space to get what we need. David Suzuki, in another article in the same series, states that:

The option of going into space allows you to pretend that technology will get our asses out of any problem so we don´t have to worry, which is just not true. Limitless resources are a fool´s dream that we can never achieve. The reality is that we are biological beings dependent on the biosphere. What kind of intelligent creature, knowing that these are our crucial limitations, would act as if we can use the Earth as a garbage can and not pay a price for that?

What kind of intelligent creature indeed? Let´s start with the majority of our political parties, in all countries. Until these simple home truths percolate into the political dialogue, humanity is on a road to nowhere. That´s why I am a Green with capital G, and proud of it.

any alternative to growth remains unthinkable, even 40 years after the American ecologists Paul Ehrlich and John Holdren made some blindingly obvious points about the arithmetic of relentless consumption.

The Ehrlich equation, I = PAT, says simply that the impact (I) of human activity on the planet is the product of three factors: the size of the population (P), its level of affluence (A) expressed as income per person, and a technology factor (T), which is a measure of the impact on the planet associated with each dollar we spend.

Take climate change, for example. The global population is just under 7 billion and the average level of affluence is around $8000 per person. The T factor is just over 0.5 tonnes of carbon dioxide per thousand dollars of GDP – in other words, every $1000 worth of goods and services produced using today’s technology releases 0.5 tonnes of CO₂ into the atmosphere. So today’s global CO₂ emissions work out at 7 billion × 8 × 0.5 = 28 billion tonnes per year.

The Intergovernmental Panel on Climate Change (IPCC) has stated that to stabilise greenhouse gas levels in the atmosphere at a reasonably safe 450 parts per million, we need to reduce annual global CO₂ emissions to less than 5 billion tonnes by 2050. With a global population of 9 billion thought inevitable by the middle of this century, that works out at an average carbon footprint of less than 0.6 tonnes per person – considerably lower than in India today. The conventional view is that we will achieve this by increasing energy efficiency and developing green technology without economic growth taking a serious hit. Can this really work?

With today’s global income, achieving the necessary carbon footprint would mean getting the T factor for CO₂ down to 0.1 tonnes of CO₂ per thousand US dollars – a fivefold improvement. While that is no walk in the park, it is probably doable with state-of-the-art technology and a robust policy commitment. There is one big thing missing from this picture, however: economic growth. Factor it in, and the idea that technological ingenuity can save us from climate disaster looks an awful lot more challenging.

¨Growth¨ 1750 to 2000 Click to enlarge