Oddly, the era of modern, triumphal, deregulated finance was much shorter than the lifespan of its apparent antithesis, the old Soviet Union. Here were two systems, very different, yet equally centralising of power and privilege, and arrogantly certain of their own mission. Both, also, left an awful mess behind.

Twenty five years on from the "big bang" in the City of London we can survey how the period of great deference to finance reshaped our landscape. Consequences are everywhere in the results of an economic scorched earth policy, still unfolding in business failures, instability, unemployment, loss of public services and recession.

But as well as the way in which untethered finance fuelled expansion and divergence in the global economy, it equally re-engineered society and the environment. Alongside the financial explosion have been others in debt-driven over-consumption, greenhouse gas emissions and inequality. New Scientist magazine last week reported that "our current emissions trajectory is close to the worst case scenario of the intergovernmental panel on climate change".

Twenty five years ago the concentration of carbon dioxide in the atmosphere was 347 parts per million (ppm); today it is 389ppm. The level in 1986 just happens to have been almost exactly the safe concentration that Nasa climate scientist, James Hansen, argues we need to return to. At the moment, however, we are heading towards 1000ppm, or higher, by the end of the century. That's a level generally considered so bad from a human point of view, it is beyond apocalyptic, if such a state is imaginable.

Just as finance loosed its moorings from the real economy, the economy has loosed its moorings from the real world. The other great destabilisation over the last quarter of a century has been the growth of inequality. In the large majority of OECD countries inequality rose from the 1980s. Inequality matters, pushing up a wide range of social costs, weakening the social fabric and producing less convivial places to live. While things have been bad in English-speaking countries such as the United Kingdom and United States, the negative trend has caught up with traditionally more equal countries such as Denmark, Germany and Sweden. Here, inequality grew more over the last decade, according to the OECD, than anywhere else, and it rose in 17 out of 22 countries for which comparable data was available.

Globally, the share of the benefits of economic activity reaching the poorest – those on less than $1 per day – fell dramatically between the 1980s and 1990s. Inequality also rose even in the major developing countries, India and China, which fared economically much better than, for example, did most of Africa.

As well as within countries and the global population as a whole, intergenerational gaps are opening up too, as recent ILO figures revealed young people making up a disproportionate share of both the unemployed and the working poor, and youth unemployment hitting a record high in the UK.

Ironically, it took the US comedian Jon Stewart, on his spoof news programme, the Daily Show, to point out that no one in the business media, who filter our understanding of finance, either called the economic crisis before it happened, or championed the need for reform of the banks and financial institutions.

As nature abhors a vacuum so, it seems, does culture and politics. The Occupy movement has, almost by accident, taken on the role of self- and public education about the financial system. Here are unpaid amateurs attempting a necessary critique of finance that paid professionals woefully failed to provide. And, of course, they are being damned for doing so.

The recent riots and lootings were a dark reflection at the economic bottom of society of the excessive, and often criminal, sense of entitlement displayed by those at the top, whether in MPs' expenses scandals or bankers' highly paid, publicly underwritten reckless bets. It must be confusing to be young, seeing rioters rightly condemned, but then to witness others intimidated and kettled for constructively protesting in favour of a more stable and fair economy.

"Have you got a bank account?" sneered the BBC Radio 4 Today programme journalist at a protester at the occupation outside St Paul's cathedral – as if having one, without which it is almost impossible to function in society, invalidated any proposals they might have for reform of a system brought to the point of collapse by speculative investors.

It's fashionable to say that the protesters' demands are too broad and vague. Yet, what they are achieving is to reclaim a public realm for debate and engagement, one that the privileges given to finance have done so much to destroy. If nothing else, practising a different kind of politics and calling for finance to be made subservient to useful social, economic and environmental purposes, to make things better rather than worse, is enough for one demonstration. And, in contrast to government policy, I'm fond of JM Keynes's observation that it is it is better "to be broadly right than precisely wrong". I can think of no better, more appropriate place to mark the anniversary of the big bang today than at the occupation outside St Paul's. And that is where I will be.