For the first time in 40 years, the UK has to re-consider its trading policy. At the moment, there is plenty of talk about “falling back” onto World Trading Organisation (WTO) rules in the event of a no-deal Brexit, an outcome which Theresa May’s giant game of ‘chicken’ makes dangerously likely. And indeed, if this is what happens, the UK will find itself solely under the minimalist rules-based trading system of the WTO.

Ideas for a Radical Green Manifesto

Introduction: the big picture

Green politics starts from the realities we now find ourselves in. Human beings are changing the planet in fundamental ways – altering the atmosphere and climate, reducing biodiversity and trashing ecosystems. This is the Anthropocene, and human impacts are going beyond the boundaries that have maintained the planet in a relatively stable state.

At the centre of human pressures on the planet are two forms of growth – economic growth and population growth. Both are powerful and complex forces.

The triggering of Article 50 earlier this week starts a new phase in the arguments about Brexit. The various negotiations that are now going to take place will in a big way determine what sort of country the UK becomes - and even whether it continues to exist at all.

Several different types of future are possible. The ones already on the political agenda are easy to outline:

(1) The UK does a deal with Trump's America to become effectively the 51st state - lowering environmental, labour, and corporate standards in order to get a deal done.

Most voices in favour of Brexit seem to offer little more than narrow nationalism, xenophobia and racism.

Such associations make it feel impossible for most Greens and progressive thinkers on the left to vote Leave in the upcoming UK referendum.

And that settles it in the minds of some: one 'has' to vote Remain. Anything else feels 'unprogressive', reactionary, even downright dangerous.

The 'austerity' issue is very much in the news. In last weekend's Observer, for example, it popped up in several articles.

On the front page a number of economists are quoted as supporting Jeremy Corbyn's "anti-austerity politics".

Inside there is an opinion piece by economics correspondent William Keegan who credits Corbyn for foregrounding the issue and challenging orthodox arguments for government spending cutbacks.

On another page, a "young Labour supporter" explains why she supports Corbyn because of his stance on "Tory austerity".

Like many Greens, I'm a huge fan of Jeremy Corbyn. I'm hoping that he wins the Labour Leadership election – and the latest polling suggests that he will. At the same time, I'm a Green, and without one shred of doubt I'm going to stay a Green. For Corbyn – for all his many virtues – is no Green. For he does not have an ecologistic approach.

Spring 2007: the high-water mark of self-confidence for economic neo-liberalism. In March, both Henry Paulson and Ben Bernanke publicly stated that they saw no danger of recession, and that the subprime fiasco had been ‘contained’. As late as mid-May, with the sub-prime crisis in full throe, still Bernanke felt able to say this: Importantly, we see no serious broader spillover to banks or thrift institutions from the problems in the subprime market. In July, Paulson claimed: This is far and away the strongest global economy I’ve seen in my business lifetime; and on August 1st, I see the underlying economy as being very healthy. Neo-liberalism remained a movement triumphal around the world. No bunch of poverty-stricken mortgage-defaulters – who could conveniently be blamed for the little local difficulty – were going to derail this ideology.

George Monbiot is correct in his praise of Thomas Piketty's proposal for a wealth tax to counteract the insane levels of inequality now generated in our world, and in pointing out that only the Green party is prepared to back this obvious idea. However, we should be careful not to let Piketty's helpful intervention in the debate blind us to the severe limits of his own stance in political economy.

What would a post-growth world look like? Some would argue that it is not difficult to imagine a world without growth, as many countries are already living in it.

Japan stagnated for a decade and its economy has been left hollowed-out. Much of Europe is in negative or near-zero growth in the wake of the global economic crisis, and in none of these countries can a lack of growth be viewed as a good thing.

We see before our eyes the human cost of economic systems that are dependent on constant growth to function. We currently rely on growth for all kinds of purposes. As a substitute for the redistribution of wealth, for example - so long as everyone is getting richer, why worry if some are getting much richer than others?

The UK has just experienced its annual budget announcement from the Government. It contained an extraordinary attack on the eco-agenda, including cuts to energy costs for manufacturers. On the BBC Radio 4 Today Programme this morning, Ed Balls, Labour’s Shadow Chancellor, backed this policy to the hilt. The budget celebrated instead ‘economic growth’ that has been achieved in the last year or so: Balls’s only cavil was that there could have been even more of it.

This GDP growth that is being celebrated by the Chancellor, George Osborne, and seemingly by nearly everyone else, is another unsustainable boom in consumption that is leaving behind those dependent on food banks and the long-term jobless. We will never have a stable, resilient economy, and we will never cease wrecking the planet so long as we chase economic ‘growth’ rather than economic resilience and rely on ‘trickle-down’ economics to look after the poor. In a wealthy country like Britain, we don’t need GDP growth; we need shorter working hours, flexible working, a Living Wage, family life, leisure time and rewarding work.