In January this year, I visited friends in Miami. One of the most urgent topics of conversation was about what they saw as the greatest problem faced by the city – rising water levels, and a long-standing reluctance on the part of government and business to take the necessary steps to control the extensive damage.

From inundated homes, shops and roads, to fresh water pollution and sewage being forced upwards, the impacts are widespread. In a Christian Aid report (pdf) published last week, Miami ranked ninth in a list of cities most at risk from future coastal flooding as a result of sea level rises. Supported by data from the Intergovernmental Panel on Climate Change, projections for the year 2017 suggest that Kolkata and Mumbai, both in India, are most exposed to coastal flooding. Bar Miami, the top ten cities are all in Asia.

Facebook Twitter Pinterest A woman walks through a flooded street in Miami Beach, Florida. Photograph: Joe Raedle/Getty Images

As global water levels rise, as parts of Florida experience the heaviest rain since records began, as the flooding and salination of farmland in Bangladesh increases, the risk to coastal cities can be seen for what it is – a sign of the apparently inexorable effects of a high-carbon economy on a fragile environment.

It is not a demand for economic stagnation, nor a matter of having some sort of anti-business agenda

But what is also clear from the Christian Aid research is how ecological disaster intensifies inequality. In prosperous nations it is the poorest who are most at risk from environmental changes such as those Miami faces because they have the least means to cope with or move away from the problem. In developing countries, coastal cities and their surrounding regions have even less in the way of defence.

Business as usual – that familiar and illusory process – will simply deepen the gulf separating the economically secure from the insecure, at least in the short term. In the long run, to paraphrase Keynes, we are all insecure.

There are measures that can be, and are being, taken with the help of NGOs and other civil society groups to limit the damage. During last year’s flooding in Myanmar and Bangladesh, for example, Oxfam distributed water, hygiene kits and cash grants, and worked with other international NGOs to coordinate the humanitarian response.

But the underlying question is becoming more and more pressing: what is it about our prevailing global model of economic growth that apparently blinds us to the cost of the high-carbon system? A process of so-called growth that inexorably increases the distance between rich and poor in one way or another ought to look nonsensical to us.

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Economic activity is still so often defined in terms of an unending upward spiral of consumption in a materially limited environment. Are we looking hard enough at the contradictions here? Are we asking what kind of economies are sustainable?

The launch this week of the Centre for the Understanding of Sustainable Prosperity, headed by Professor Tim Jackson who wrote the groundbreaking 2011 report Prosperity Without Growth, looks to galvanise a more urgent discussion of these issues. It is not a demand for economic stagnation, nor a matter of having some sort of anti-business agenda – this is lazy criticism – but for the question to be clearly put: what does prosperity mean in a world of environmental limits?

The old paradigm of economic development and prosperity assured us that infinitely expanding consumer choice increased and guaranteed our free agency. It is time to wake up to the fact that this paradigm makes us passive to processes outside our control and condemns us in the long term to a losing battle with the limited material world we share. If we want to be genuinely free agents, we need to turn this model on its head.