Individual protesters will have their own take on how they think we can save the planet, but they will all broadly agree that what they are opposed to is a globalised capitalism, which has dramatically changed our lives in the last generation.
Between the Second World War and the early to mid-1970s, there was a broad agreement in Europe and north America that economic prosperity depended on governments regulating their domestic economies through their control over interest rates, taxation and public spending.
They could, thus, control the level of demand in the economy and so smooth the effects of the business cycle, aided by substantial public sectors not driven by the profit motive.`
This in a context where exchange rates were pegged to the dollar, stabilising the terms of international trade, and exchange controls prevented large, speculative movements of money around the globe. Labour movements were strong enough in this environment to demand policies which would sustain full employment – for men, at least – thereby bidding up wages, while inequality was also reduced by expanding welfare states.
Workers expected to be treated as equal citizens, in other words, as evidenced in Northern Ireland in the 1960s by the growth of the Labour Party, the adoption by the Unionist Party under Terence O'Neill of state-interventionist rhetoric and the emergence of the civil rights movement against discrimination in the labour market and public provision.
All this was to change and change utterly, as one by one these policy levers guaranteeing security and stability were ditched in favour of the new language of 'free markets'.
The United States, unable to finance its unwinnable war in Vietnam, allowed the dollar to float. The very organisations established to stabilise the post-war economic order – the International Monetary Fund and the World Bank – increasingly told developing countries to privatise their public organisations and 'liberalise' their relationships with the international financial markets.
In the UK and the US, first-past-the-post electoral systems, favouring a winner-takes-all politics, allowed the election of Margaret Thatcher and Ronald Reagan as crusading conservatives determined to destroy the organisations workers established for their collective protection.
Allied to a dramatic skewing of the tax system in favour of the wealthy, curbs on 'inflationary wage increases' and the abandonment of full employment reversed the trend towards equality on either side of the northern Atlantic in favour of the very wealthy and the owners of capital.
The gap between rich and poor has now returned to the yawning levels of the 1920s before the Wall Street Crash – the era of The Great Gatsby being revisited on our cinema screens.
And, as in that earlier period of globalisation, the lack of regulation of markets has led to ever more unstable gyrations and ever-more frequent financial crises – until the chronic, global crisis of the past five years.
It is this vast inequality which motivates many of the G8 protesters – as well as the manner in which power has been sucked out of popular democratic control and into the hands of such a tiny group of powerful men (as they nearly all are), representing the rich or rising states, assembled in Fermanagh later this month.
An evocative symbol has been how a depressed Enniskillen has been tarted up, with closed shops painted with bright frontages suggesting prosperity, for the G8 visitors passing in their limousines.
For many protesters, too, this world of every-growing insecurity will sit oddly with the 'security' presence offered (at vast public expense) by 8,000 police.
Their riot training will hardly prepare them for the facilitation of peaceful protest, a fundamental feature – as recent events in Turkey have highlighted – of a democratic society.
Some protesters, too, will be motivated by the ultimate fear: that the rapacious global capitalism which has emerged from this unleashing of democratic regulation may even render unliveable the planet on which it depends within another generation or two, as finite natural resources are rapidly consumed, biodiversity destroyed and, above all, catastrophic climate change is threatened. In the age of the internet, the genie of globalisation can hardly be put back in the bottle.
Yet that very interconnectedness provides unprecedented opportunities to place capital under new, transnational constraints in the interests of the citizens of the world.
A simple example is how global attention has been drawn by the recent building collapse in Dhaka to the plight of (mainly female) textile workers, super-exploited to produce garments for High Street retailers in Europe and America.
The pressure of international opinion, mobilised by NGOs and trade unions, has forced the clothing giants to begin to clean up the act of their Bangladeshi suppliers.
Equally, modern technology makes it technically straightforward to place a levy on international financial transactions – a 'Robin Hood tax'.
This would not only dampen the swirl of speculative trillions around the world's financial centres, but would raise tens, or hundreds, of billions of dollars a year, which could be used to finance 'green' development in the global south, rather than a disastrous replication of the model which has so imperilled our fragile ecological fabric.