The 21st meeting of the Conference of the Parties of the UN Convention of Climate Change begins with expectations of success. Having been engaged in this process from the very beginning – indeed in imagining its beginning – I can see we have come a long way in reaching this point. What is now imperative is whether any success in Paris results in action in the real world.

First, some fundamentals: we are all connected. The problems of climate change connects us – and the solutions we may find connect us. No nation can protect itself from the consequences of climate change on its own, no matter how powerful, and no unilateral action succeeds.

The world has changed since the first COP climate conference in 1992. The law has to respond to real world fact. There is little sense in splitting the world between developed and developing countries when two thirds of the world’s emissions are in these emergent nations. In 100 years, on a business-as-usual trajectory, we face a 50% probability of 6-7 degree warming (FCO Risk Assessment report led by Sir David King 2015). Human society dissolves.

We have to recognise that the Paris summit is not going to mark the end of the threat caused by climate change. The offers on the table are a step up from what we feared a few months ago – but they will leave us closer to a 3 degree pathway than 2 degrees. Far too little attention has been directed to financing for adaptation. The African governments whose citizens will have to live with mounting climate risk are right to be concerned.

Yet this is a moment political leaders must seize. There is a new mood of constructive dialogue between China and the United States. India is an emerging solar power; and whatever their differences, governments across the world understand one thing – we are in this together.

The problem is so complex, so dispersed, that it is sensible to open up to a multitude of responses. Whatever works. The top down approach can only move you so far. It assumes the negotiators know the answers and that all the resources – financial, technological, human – are to be found in rich countries. We know that is not the case. Indeed, it would be arrogant to declare it so.

What is interesting about this agreement, emerging productively out of the failure of Copenhagen, is that it is based on what my old Professor Philip Allott coined as mutually related declarations of intent, supported by effective monitoring systems, and it is universal. This now seems a better way of managing the complexity. There will be few occasions when an 'I win, you lose' contractual bargain is effective.

Yet we shouldn’t make a fetish of the legally binding nature of this agreement – what is required is a remaking of the world. In our minds. The transformation we must make starts with imagination, moves through organisation and ends in a changed material world.

That change cannot happen without finance. Real investment. Trillions need to move into the low carbon economy of the future.

Money is instrumental – and public money is not superior to private money. It’s not worth more, it’s not morally superior and it’s all ours anyway. Taxes, charges, pensions, insurance, savings, even sovereign wealth properly understood. All ours, and available to be directed to public goods if we so decide.

In Paris, there will be many promises from across the spectrum of providers. We must turn our attention to scale and effectiveness; do they match the need, will the capital be directed to the long term objective of the Agreement and did we accelerate the flow?

Money and innovation must be combined. From enterprises of all shapes and sizes and from anywhere. Google is the largest corporate renewable energy investor in the world, Morocco just opened the largest concentrated solar plant in the world, Bill Gates just pledged more of his fortune to clean energy.

So, we are all connected to both problem and solution. The original agreements were largely about responsibility and burden sharing. Quite right. Those ideas still apply. In addition, there is opportunity distribution, self-organisation in networks of interest extending way beyond the nation state, and 150 national business plans for transforming our economy.

Finally, there is security. As we concentrate on what binds us, accept that climate change amplifies risk through water conflict, migration, scarcity – something which has long been understood by the military. At the same time, the Paris 'outcome' asserts a national interest in investing in the contributions of other countries. It reduces risk and cost to us, it aids the choice of infrastructure, it stimulates design creativity and it accentuates our essential humanity.

As Nick Stern said at ODI, citing Yann Arthus-Bertrand: 'it’s too late to be pessimistic'. I would add that it is also right to be a paradoxical optimist.