What would happen to the world if, with the snap of our fingers, we shifted all our energy supplies to renewable sources overnight? You might be surprised at the answer: not much, at least for biodiversity and ecosystems.

Certainly, it might solve the climate problem, but I have canvassed this question in a number of different places, and the answers usually converge on this: we would still wreck Earth’s ecosystems. And what’s more, we’d still wreck them on a timescale similar to the trajectory that we’re on already.

The reason is that climate change is a problem, not the problem. At the moment much of the focus is on climate and there’s no doubt this is a problem that requires emergency action now to see if we can avoid the worst of the tipping points. But there are many “showstoppers”, any and all of which can bring humanity and biodiversity to a sticky end.

Without biodiversity in all its forms, which creates the complex web of interrelated systems that hold the biosphere in homeostasis, things that we take for granted such as temperature, the level of oxygen in the atmosphere or the even concentration of salt in the sea, will no longer support the life we know.

Something other than climate change is driving the current mass extinction. The impacts of climate change, though potentially catastrophic, are in the main yet to come – albeit sooner than we have previously expected.

The current trajectory of biodiversity loss and ecosystem collapse is being driven by cutting down forests, over-fishing, chemical pollution, soil degradation and erosion, habitat destruction, desertification and so on. These activities are all a function of the vast amount of energy we have at our disposal. We have too much and, as we use it, we damage ecosystems.

We are well outside the reasonable limits of our energy and material use. Globally about 51% of all energy use is industrial, 20% is transport, 18% residential and 12% commercial. But all is interconnected and almost all demands over and above our basic needs lead back to increased physical and chemical destruction of ecosystems.

So what are the reasonable limits within which we can operate? I think that there are four main factors to consider.

First, according to the Global Footprint Network, we are already consuming 1.5 times more than the earth is able to renew each year. To bring our material and energy credit card back into balance we need to reduce our resource draw by 33%.

Second, world population is almost inevitably going to increase by another 25%. To accommodate these newborns, we must reduce our resource draw by a further 25%.

Third, on a scale of wealth, the top 20% of humans are 40 times richer than the bottom 20%. This is morally and geopolitically untenable. It would seem reasonable for the top 20% to reduce consumption by a factor of 4 and the bottom 20% to increase by a factor of 4. The gap between rich and poor would then be a more reasonable factor of 2.5 times. The reduction associated in resource draw for countries like Australia would be a further 75%.

Finally, we need to build in safety margins. When we build a bridge, we build in a resilience factor. According to the New South Wales government, the safety factors for the steel in the Sydney Harbour Bridge ranged from 1.9 to 2.5.

The steel chosen by Dorman, Long & Co. Ltd. for the main beams of the arch was silicon steel. In compression these beams were between 2.2 and 2.4 times stronger than the expected stress on them. Equally, we should not consider using Earth’s resources with no margin for the unexpected. If we were to choose a factor of 2 for planet Earth, then this implies a further reduction in resource draw of 50%.

Multiply these factors together and we end up with a reduction to about 6% of what we currently consume in energy and materials in Australia. That is 16 times less than we now use.

This is the goal we need to set, without which we have little chance of hitting the target - survival. I hope that survival is what most people want.

Suppose we, humanity, survive the current planetary sustainability crisis relatively unscathed and, in 100 years time, can say that we have stabilised global ecosystems. By this I mean: biodiversity has ceased its dive into mass extinction; CO 2 is under control; global population is in a manageable decline; chemical and physical damage to ecosystems is being reversed and healed; and we are living within our planetary means.

To countenance such a deep and radical change requires us to rethink the entire way we organise humanity, politically, economically and socially.

I am sometimes asked where to start; I don’t think the problem is technical. It lies deep within us. At present we have adversarial systems of governance - both political and economic. These work in an open system, a world with few humans, where wounded places and populations can be abandoned for new territory.

But in a closed system, full of humanity, these wounds must be healed. Only cooperative systems of organisation, both political and economic, can achieve this.

We need to be talking about what might work and experimenting with different ideas. We don’t have long to do this, but it does offer the opportunity of an extraordinary renaissance.