The pursuit of infinite economic growth is driving climate breakdown and producing ecologically toxic architecture, argues Phineas Harper, one of the chief curators of the Oslo Architecture Triennale.

Shipwrecked in a storm, you might avoid a watery grave if by chance the top of a mahogany grand piano came floating past. Clambering aboard this improvised raft, you could cheat death, but your miraculous escape would not mean that the best design for a life jacket is a piano top, nor that ships should ensure the safety of their passengers by stocking an abundance of Steinbergs.

As Richard Buckminster Fuller pointed out in this allegory from his 1968 Operating Manual for Spaceship Earth, a makeshift solution which just about works for the time being should not be conflated with the best tool for the job.

Yet as a species we are clinging to all manner of piano tops – systems, practices and materials that allow society to stumble along despite being evidently unfit for purpose and increasingly unable to weather the turbulent waters ahead.

"If we invented concrete today, nobody would think it was a good idea," argued Michael Ramage, head of the Centre For Natural Material Innovation at the Architecture of Emergency summit in London last week. "It's liquid, needs special trucks, takes two weeks to get hard and doesn't even work if you don't put steel in it. Who would do that? — Nobody!"

Global political orthodoxy declares growth is good, and that more is always more

We have built up such a vast infrastructure around manufacturing concrete that despite its deep flaws, it seems impossible to shake its ubiquity in construction. The predominance of concrete is just one of the many ways in which the piano tops of yesterday shape the possibilities of tomorrow.

The paradigm within which our buildings are designed unswervingly limits their potential to reproducing the status quo. Like using a knife to drive a screw, or pliers to loosen a nut, we are stuck making do with shoddy tools, both physical and economic.

Since the 1930s, gross domestic product (GDP) has been our main method of measuring a country's economy and has come to define the welfare of its people. Global political orthodoxy declares growth is good, and that more is always more.

However this singular pursuit of an infinitely growing economy masks the reality that GDP is a misleading indicator of social health and the harm that excessive economic growth causes. It is now clear that an economy based on increasing GDP comes with increasing energy consumption, extraction of natural resources, and greenhouse gas emissions; all accelerating environmental collapse.

The logic of economic growth commodifies everything in its path. Museums are reduced to beacons for attracting investment. Universities sell education for profit

In addition, as the scientist Vaclav Smil has shown, "once you reach a certain point, the benefits of GDP growth level off". Excessive GDP does not improve life expectancy, social progress, happiness or equality but is driving us off an ecological cliff. The story we have based our economic system on is a toxic myth.

The logic of economic growth commodifies everything in its path. Museums are reduced to beacons for attracting investment. Universities sell education for profit. Homes become real estate vehicles. We have sleep walked into an system that converts relationships to services and commons to commodities.

There are some who argue that despite the harm it causes, growth has given the world great technological and cultural advances so should be venerated. This argument now rings as hollow as those apologists who claim India is indebted to British colonialism for its rail network, or that medical advances made in field hospitals ameliorate the horrors of war. Whatever gains can be wrought through growth, they are not worth its externalities.

The most existential, exciting and revolutionary challenge facing society, is to redesign our economy to protect the only biosphere we have

Impossible to sustain in the long term, and harmful in the short, our dependency on growth, like on concrete, must be abolished. Just as in architecture we explore new design philosophies, aesthetic languages and structural systems, we must explore alternative economies – other ways of structuring trade and assigning value.

The most existential, exciting and revolutionary challenge facing society, is to redesign our economy to protect the only biosphere we have.

Degrowth is a designed reduction of total energy and material use to realign society with planetary limits, while improving people's lives and distributing resources fairly. It is an economic model that recognises that the route to greater welfare for all is not one of more extraction and expansion, but of more sharing and co-operation.

Architects and urban designers, toiling daily at the coalface of speculative urban development, are complicit in the perpetuation of growth but we are also in a unique position to contribute towards a move away from it.

Architecture is the armature of culture, shaping and shaped by the economy in which it is constructed. What could architecture be like in an economy based on nourishing culture and nature rather than GPD?

The architecture of degrowth proposes cities of shared plenty — of nourishing culture and prioritising the production of art

What kind of architecture will we create when buildings are no longer instruments of financial accumulation? What structures will be made as collective acts of cultural expression rather than as financial ventures? From what will we build when materials are priced on their ecological, not market value. How can neighbourhood planning foster community vitality, sharing commons and participatory democracy?

The architecture of degrowth proposes cities of shared plenty — of nourishing culture and prioritising the production of art. It is a system which values the writing of love letters, amateur gardening and taking the scenic route rather than treating these economically nonproductive activities as frivolities. Degrowth is the political cause of richly expressive cities made in symbiosis with nature.

The Global Climate Strike that swept through 150 countries at the weekend was a landmark in a year of seismic political events that have underscored the urgent need for radical action to halt global heating. Governments, citizens and architects have joined forces in declaring a states of emergency — and not before time. But continuing to pursue a growth-based economy with some improved environmental measures will never be enough to avert climate breakdown.

We can mix fly ash or blast furnace slag in with cement to make concrete marginally less bad for the environment but, like GDP, it is still a piano top – a perilous raft, designed for another challenge than the one we now face, and increasingly unable to save us from the rising water.