So, as discussed in pt1, we need to green our economy not only to make us environmentally sustainability (the medium-long term priority) but also to get the economy going again (so even if you hate the green movement, you should swallow your pride). But what would a green economy look like?

I like to split the various visions of utopia into two broad catagories:

1. Eco-efficiency aka “doing more with less”

Eco-efficiency is all about numbers, such as “we need to cut carbon emissions by 80% by 2050”. It can be defined as the amount of use (utility) we can get out of each unit of resource – oil, raw materials etc with the hope that if we extract more use, we need less stuff. Estimates of what level of efficiency increases we might need range from a factor of 4 (in the famous book of that name) to over 100.

Why so high? Well, history tells us that the more efficiently we use stuff, paradoxically, the more we tend to consume – if driving becomes cheaper, we tend to drive more, or, more worryingly, use the money saved to buy a cheap flight, destroying any environmental benefit. This is known as the rebound effect.

And then there’s the problem of how efficient we can make technology – hitting Factor 10 in a house is now straightforward, but try doing it for, say, flying.

To make eco-efficiency work, we have the following options:

• Make massive efficiency gains to overwhelm the rebound effect (how many flights can one person take?);
• Restrain consumption by either restraining affluence (try selling that politically) or population growth (another political humdinger);
• Change the nature of consumption so we are consuming experience rather than ‘stuff’ – an MP3 gives you the music you want without the cardboard, plastics and metals needed to produce a CD (we’ll look at this in more detail next week).

2. Eco-system models aka “copying the solar powered cycles of nature”

Nature doesn’t do efficiency – think how many sperm a man produces over his life compared to the number of children he is likely to father (sorry if you’re reading this over lunch) – yet nature has been pretty much sustainable for at least the last billion years. It does it by creating loops of materials (carbon, oxygen, nitrogen etc) which do not systematically poison the system, powered by solar and gravitational forms of energy.

To copy nature, we need to shift to a circular economy where all waste becomes a raw material for something else  – or where we can trade materials sustainably with nature. This all needs to be powered by renewable energy. And we need to eradicate persistent poisons. None of this involves numbers – it is all or nothing. The big question is: can we actually deliver this with the levels of stuff currently in the economy? In natural cycles, energy capture is usually the constraining factor and it is true of the eco-system model – can we capture enough renewable energy? If not, and it would be a steep challenge, we’d need to make genuine eco-efficiency gains to make it feasible.

The Paradigm Shift

The two paradigms are completely compatible – for example using recovered metals will reduce carbon emissions quantitatively and using materials more efficienctly will help make the circular economy more feasible. However, as the eco-system model is the only one that will guarantee sustainability, we need to pursue it as the end point and thus the priority. Unfortunately most policy makers see eco-efficiency as the priority, so there is a requirement to reframe the debate so we get a paradigm shift.

In Part 3, we’re going to look at what’s working, and after that, what needs fixing.