Jeremy Corbyn’s win today marks a revolutionary, seismic change in British politics. But it is also so much more than that.

It’s not just the fact that he won, but that he won so decisively in the first round, with almost 60% of the vote, victorious in each of the three Labour Party ‘chapters’ – party members, affiliated supporters, and £3 registered supporters.

With so clear and strong a mandate from the Party, trades unions and cooperatives, and wider society including supposedly ‘disengaged’ young people, even his strongest detractors among Labour MPs have little choice but to go along with the euphoric tide that swept him to the leadership – no matter how little they share in that euphoria themselves.

And it is testament to Corbyn’s political integrity that his first act as Labour Leader and Leader of the Opposition was to take to the streets in today’s ‘Solidarity with Refugees’ march in London, which begins at Park Lane and ends, symbolically, at Downing Street.

Corbyn’s campaign and its resounding success have destroyed the New Labour project for good. Tony Blair and his entire legacy are reduced to rubble in an democratic earthquake of overwhelming power.

Blair himself is looking more likely than ever to end up in a court of law charged with the ultimate war crime – that of unprovoked military aggression against another nation. Others that colluded in the lies that took Britain to war in Iraq must also be fearing for the future.

But it’s the Tories who will really be quaking at the knees

But the deeper angst is on the Government side. David Cameron has good reason to fear the coming of Corbyn. His Bullingdon Club arrogance and Oxford Union debating skills will cut little ice against Corbyn, who will provide the serious, penetrating, analytical, humane opposition we so desperately need.

Any attempt by Cameron to stick with the old ‘yah boo’ style of Prime Minister’s Questions will look trivial, inept, condescending and utterly inappropriate.

For many years now he and his party have faced a Labour opposition that essentially shares their world view, so the debate has been focused on small but symbolic issues of detail. Both parties have colluded, for example, in

• economic ‘austerity’ – the imposition of deep public sector spending cuts that overwhelmingly impact on the poor, while flooding banks with cheap money to maintain booms in asset values for the exclusive benefit of the rich;
• the dismantling and privatization of the National Health Service and other essential public services;
• the idea that unaccountable corporations acting in pursuit of profit are preferable to public service, cooperative, state and community provision;
• the broad neoliberal agenda of supporting the power of international capital against people and the environment, as manifest in ‘free trade’, ‘investor protection’ and other provisions of TTIP, CETA and so on;
• nuclear power – no matter how high the cost;
• maintaining a ‘two track’ approach on climate change – giving diplomatic support to strong international agreements, while supporting fossil fuel industries with friendly policies and tax breaks;
• the desire to maintain nuclear weapons, at enormous expense, whose exclusive purpose is the mass murder of millions of people;
• membership of NATO, the world’s most powerful and aggressive military alliance;
• Britain’s role as a lackey to US power, unfailingly lending military and diplomatic support to both covert and overt US aggression whether in Iraq, Afghanistan, Libya, Syria, Ukraine or elsewhere;
• unquestioning support for key military allies of the US, notably Israel and Saudi Arabia, no matter how egregious their crimes and disregard for international law including the Geneva Conventions.

The remarkable thing about Corbyn is that he is not merely luke-warm on some of these issues in the manner of his predecessor Ed Miliband, but that he rejects the entire package outright.

That 90% of ‘common ground’ that once existed between the two parties has now entirely evaporated. From now on Labour’s opposition will be real, serious, profound and principled.

This political earthquake still has a long way to run …

Corbyn’s opposition role will of course have huge environmental implications. Uniquely among the candidates for the Labour leadership, he advanced a powerful ‘green’ manifesto which set out a series of important policies on everything from fracking and nuclear power (against) to community energy and renewables (for) and conserving the integrity of our ecosystems on land and in sea.

And now he and his shadow ministers will be vigorously advancing those policies which promise – in line with opinion polls of renewable energy and other issues – to be overwhelmingly popular.

He will also be vociferous in his opposition to the viciously anti-environmental policies of the Conservative government – for which they have so far escaped serious political consequences. No longer will Cameron, Rudd and others be allowed to get away with talking green while attacking the environment by every means available to them.

That opposition will, moreover, be reflected in the media. Often in the most unflattering terms of course – what else would you expect in the Mail, Express, Sun, Times, Star and Telegraph? But bit by bit, the truth will shine through.

Perhaps the biggest change will be reflected in the BBC, which is constitutionally required to maintain political ‘balance’ between government and opposition and which, moreover, is itself under attack from a Government determined to ‘cut it down to size’ by limiting its services and reducing its funding base.

We can therefore expect the entire ‘centre ground’ of British political thought to shift markedly to the left – in the process exposing the current government as the exteme right-wing ideologues they are.

A green and socialist alliance across the Atlantic?

But the repercussions will also be international. Corbyn’s success both reflects and will in turn inspire left wing, anti-austerity parties and movements like Podemos in Spain and Syriza in Greece.

And it will echo across the Atlantic where the polls show the avowedly socialist and environmentally committed Bernie Sanders looking ever more likely to defeat the neoconservative Hillary Clinton and become the Democratic Party’s presidential candidate.

The story of Clinton’s decline from well above 50% to below 40% has been almost precisely mirrored by Sanders’s rise, from below 10% to above 30% today – and in my book he’s the clear favourite for the nomination for all the same reasons that Corbyn won today.

If Sanders goes so far as to win the Presidency in November 2016 – an entirely credible proposition given the weakness of the Republican candidates and the likelihood of a Donald Trump split-off right-wing candidature – that raises the prospect of what would until today have looked impossible: a trans-Atlantic green and socialist alliance of Jeremy Corbyn and President Sanders.

And of course that would hugely boost Corbyn’s chances of winning the 2020 UK general election. Forget Obama’s increasingly hollow promise of “Yes we can!” – the cry will be “Yes we bloody well will!”

Not a moment too soon.

Oliver Tickell edits The Ecologist.