As the world grapples with climate change, biodiversity loss and other environmental challenges, campaigners and some academics are questioning a central tenet of modern society – that continued economic growth is desirable.
Instead, they say that the world must aim for "degrowth", or "post-growth".
Dating back to the 1970s but gaining renewed interest in the 2020s, this concept suggests that the only way for human beings to stop living beyond the Earth’s means is to scale back economic activity and consumption.
It casts doubt on the view that carbon emissions are being decoupled from economic activity thanks to technologies such as renewable energy.
"The evidence does not really show that we can decouple – in absolute terms and globally and at the speed required – emissions from growth and material footprint," says Milena Buchs, professor of sustainable welfare at the University of Leeds.
"That has big implications for what we think about how the economy should be organised."
There are numerous reasons why governments have tended to focus on economic growth, which some have argued has given the world things such as better housing, improved medical care and opportunities for varied and fulfilling lives.
In a 2020 report looking at recovery from the Covid-19 pandemic, Beth Stratford and Dr Dan O’Neill, also of the University of Leeds, highlighted key reasons, well known to economists, why continued economic growth is so often seen as necessary.
One is to prevent increases in unemployment – as efficiency improves, the need for labour falls, so the standard view is that there must be an increase in consumption to keep everyone employed.
Another factor they cite is that economies centre on debt, much of which is based on an expectation of future growth. Growth is also regarded as necessary to protect the interests of "rentiers", who include financiers and landlords.
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In their report, they suggest that safeguarding basic needs (such as the introduction of minimum income guarantees), protecting workers (for example, by supporting companies to cut hours instead of jobs), reducing exposure to debt crises and tackling rent extraction could free economies from a need for growth.
Advocates of degrowth or post-growth economics sometimes argue that gross domestic product, or GDP, is not a measure of well-being, even though it is sometimes regarded as having this all-encompassing significance.
Prof Buchs highlights that everything from oil spills to natural disasters, divorce and crime can result in increases in economic activity. At the same time, she says, GDP excludes much that is widely regarded as positive for well-being, such as informal care, voluntary work and time spent with friends.
While numerous alternative metrics have been developed, she says that it is "incredibly difficult" to agree on which to use.
Degrowth or post-growth approaches typically involve some scaling back of consumption and what may be seen as people’s insatiable desire for more things and varied experiences, including global travel.
While some may doubt that people would accept more modest lifestyles, Prof Buchs suggests that self-interest and consumption are not hard-wired into human nature.
"I struggle a bit to believe humans are necessarily always like that," she says. "How we think, how we act, is shaped by the institutions around us.
"If you were going to transform economies to a more equity-based, post-growth collective-interest-oriented way of thinking, that would have an impact on what people value."
Some advocates of "green growth" suggest that by transitioning to less harmful industries, the world can achieve net zero without requiring people to accept major lifestyle sacrifices.
In the US, there has been a major push for green growth through the Inflation Reduction Act, which has stimulated huge investments thanks to tax breaks and subsidies for green industries.
Among those who broadly take the view that green growth is the answer is Sam Fankhauser, professor of climate economics and policy from the Smith School of Enterprise and the Environment at the University of Oxford.
He says that emissions have been successfully decoupled from greenhouse gas emissions in about 20 countries, among them the UK, where there has been, in particular, a shift away from using coal to generate energy.
According to figures from OurWorldinData, between 1990 and 2019 the UK’s per capita GDP grew 50.18 per cent, but its consumption-based CO2 emissions (which take account of the way that some emissions are "offshored" when a country imports manufactured goods) were down 34.18 per cent.
Advocates of degrowth or post-growth say that despite what is often called decoupling having happened in many countries – albeit still a fraction of countries – global emissions continue to rise, so much tougher action is needed to avoid the worst effects of climate change.
"We need very, very steep emission reductions per year to stick to the carbon budget," Prof Buchs says.
According to UN figures, emissions must be slashed by 45 per cent by 2030 if average global temperatures are not to rise more than 1.5°C above pre-industrial levels, but nothing close to that is likely to be achieved.
Prof Fankhauser thinks that it could be possible for people to maintain similar lifestyles to today while dealing with climate change, saying that key transitions, notably of surface transport (to electric) and energy generation (to renewables) are "close to or past the tipping point".
"Once you come out the other end, there’s no reason to believe that an economy powered by cars that are electric and renewable energy and hydrogen that fuels industry ... structurally or permanently must generate less prosperity," he says.
But he says that politicians are "too timid" and shy away from difficult messages. There is likely to be short-term disruption as "green innovation" leads to "creative destruction" in some industries, having consequences that are "noticeable and painful for many".
He said he thought the world would reach net zero but also that the concern is "we’ve left it too late" and that average global temperatures may rise more than 2°C above pre-industrial levels.
Preventing the loss of biodiversity may be even more difficult, he says, because there are fewer technological fixes of the kind that could deal with global warming. The world is experiencing what is often termed its sixth mass extinction as natural habitats are destroyed and species are lost for ever.
"There’s a bigger element of land competition," he says. "That incurs probably more choices – land is a finite thing, so it’s more of a zero-sum game there.
"The very optimistic people who looked at that, point out that a huge part of the issue is agriculture, which simplifies the problem in the sense that if you can sort out this one sector, you’ve sorted out a big part of the problem."