We are still living in the long 20th century. We are stuck with its redundant technologies: the internal combustion engine, thermal power plants, factory farms. We are stuck with its redundant politics: unfair electoral systems, their capture by funders and lobbyists, the failure to temper representation with real participation.

And we are stuck with its redundant economics: neoliberalism, and the Keynesianism still proposed by its opponents. While the latter system worked very well for 30 years or more, it is hard to see how it can take us through this century, not least because the growth it seeks to sustain smacks headlong into the environmental crisis.

Sustained economic growth on a planet that is not growing means crashing through environmental limits: this is what we are witnessing, worldwide, today. A recent paper in Nature puts our current chances of keeping global heating to less than 1.5C at just 1%, and less than 2C at only 5%. Why? Because while the carbon intensity of economic activity is expected to decline by 1.9% a year, global per capita GDP is expected to grow by 1.8%. Almost all investment in renewables and efficiency is cancelled out. The index that was supposed to measure our prosperity, instead measures our progress towards ruin.

But the great rupture that began in 2008 offers a chance to change all this. The challenge now is to ensure that the new political movements threatening established power in Britain and elsewhere create the space not for old ideas (such as 20th-century Keynesianism) but for a new politics, built on new economic and social foundations.

There may be a case for one last hurrah for the old model: a technological shift that resembles the second world war’s military Keynesianism. In 1941 the US turned the entire civilian economy around on a dime: within months, car manufacturers were producing planes, tanks and ammunition. A determined government could do something similar in response to climate breakdown: a sudden transformation, replacing our fossil economy. But having effected such a conversion, it should, I believe, then begin the switch to a different economic model.

‘In the Brazilian city of Porto Alegre , the infrastructure budget is allocated by the people.’

Land value tax and community right to buy help to create what I call a politics of belonging

The new approach could start with the idea of private sufficiency and public luxury. There is not enough physical or environmental space for everyone to enjoy private luxury: if everyone in London acquired a tennis court, a swimming pool, a garden and a private art collection, the city would cover England. Private luxury shuts down space, creating deprivation. But magnificent public amenities – wonderful parks and playgrounds, public sports centres and swimming pools, galleries, allotments and public transport networks – create more space for everyone at a fraction of the cost.

Wherever possible, such assets should be owned and managed by neither state nor market, but by communities, in the form of commons. A commons in its true form is a non-capitalist system in which a resource is controlled in perpetuity by a community for the shared and equal benefit of its members. A possible model is the commons transition plan commissioned by the Flemish city of Ghent.

Land value taxation also has transformative potential. It can keep the income currently siphoned out of our pockets in the form of rent – then out of the country and into tax havens – within our hands. It can reduce land values, bringing down house prices. While local and national government should use some of the money to fund public services, the residue can be returned to communities.

Couple this with a community right to buy, which enables communities to use this money to acquire their own land, with local commons trusts that possess powers to assemble building sites, and with a new right for prospective buyers and tenants to plan their own estates, and exciting things begin to happen. This could be a formula for meeting housing need, delivering public luxury and greatly enhancing the sense of community, self-reliance and taking back control. It helps to create what I call the politics of belonging.

But it doesn’t stop there. The rents accruing to commons trusts could be used to create a local version of the citizens’ wealth funds (modelled on the sovereign wealth funds in Alaska and Norway) proposed by Angela Cummine and Stewart Lansley. The gain from such funds could be distributed in the form of a local basic income.

And the money the government still invests? To the greatest extent possible, I believe it should be controlled by participatory budgeting. In the Brazilian city of Porto Alegre, the infrastructure budget is allocated by the people: around 50,000 citizens typically participate. The results – better water, sanitation, health, schools and nurseries – have been so spectacular that large numbers of people now lobby the city council to raise their taxes. When you control the budget, you can see the point of public investment.

In countries such as the UK, we could not only adopt this model, but extend it beyond the local infrastructure budget to other forms of local and even national spending. The principle of subsidiarity – devolving powers to the smallest political unit that can reasonably discharge them – makes such wider democratic control more feasible.

All this would be framed within a system such as Kate Raworth’s doughnut economics, which instead of seeking to maximise growth sets a lower threshold of wellbeing, below which no one should fall, and an upper threshold of environmental limits that economic life should not transgress. A participatory economics could be accompanied by participatory politics, involving radical devolution and a fine-grained democratic control over the decisions affecting our lives.

Who could lead this global shift? It could be the UK Labour party. It is actively seeking new ideas. It knows that the bigger the change it offers, the greater the commitment of the volunteers on which its insurgency relies: the “big organising” model that transformed Labour’s fortunes at the last election requires a big political offer.

Could Labour be the party that brings the long 20th century to an end? I believe, despite its Keynesian heritage, it could. Now, more than at any other time in the past few decades, it has a chance to change the world.

• George Monbiot is a Guardian columnist