When it comes to urban planning, past and present, one can’t escape the time-tested truth that the road to hell is often paved with good intentions. Cases in point include the ravaging of city centres and neighbourhoods to accommodate private cars, touted as progress and comfort in the 20th century, or the excessive ambitions of "smart city" utopias of more recent times, which seek to optimise every element of urban life for efficiency. Another example that illustrates that even the seemingly most noble cause can have unwanted and lamentable consequences concerns the recent surge of urban greening interventions in cities worldwide. This might sound puzzling at first glance. After all, what could be wrong with city governments and developers promoting eco-conscious projects aimed at reintroducing nature into urban landscapes and improving cities' biodiversity, public health, and quality of life – one pocket park, greenway, or rooftop garden at a time? Well, it turns out quite a lot if you ask researchers who have studied them.

Urban greening initiatives, irrespective of their initial intentions, can lead to several unintended consequences that may undermine their positive impact, the most notable one arguably being what is referred to as "green gentrification." Green gentrification occurs when green spaces in urban areas spark investment and draw higher-income residents, pushing up property values and living costs and driving out low-income and marginalised groups who can no longer afford to live in the affected areas. When green gentrification occurs, it means that the advantages of urban greening will inevitably not be shared equally. While affluent groups benefit, lower-income residents may find themselves excluded, widening the gap between the rich and the poor.

A prominent example of this phenomenon is New York City's High Line. The transformation of an abandoned elevated rail line into a thriving, linear park is widely credited for dramatically reshaping Manhattan’s westside, creating a mix of winners and losers in the process. The park itself is widely admired, and many of its impacts are appreciated. However, it has also led to a rampant real estate and construction boom as well as soaring property prices that displaced countless businesses and residents from lower socioeconomic and ethnic minority backgrounds and exacerbated existing socioeconomic and environmental inequalities. Since the High Line opened in 2009, similar developments have been observed in numerous other cities, and there is now a large body of scholarship scrutinising the ripple effects of urban greening initiatives and how they reshape urban environments. This scholarship challenges what Isabelle Anguelovski, James Connolly and Anna Livia Brand refer to as the "urban greening orthodoxy", which is the prevailing discourse in urban planning and policy that portrays urban greening as an unambiguous good while overlooking potential drawbacks and disregarding the often problematic social and spatial impacts of these new initiatives.

Furthermore, they and other critical researchers raise questions about the motives and rationales driving the recent wave of greening initiatives, pointing out that many may not be as benign as they seem. They argue that projects often tend to be driven by elite interests and growth-oriented development logic, prioritising economic expansion over social and environmental welfare. They accuse developers of using green amenities to "greenwash" contentious projects that might otherwise face public resistance and, banking on the idea that "green sells," boost their profits.

A look around our cities and at what happens within them suggests these critical perspectives have some merit. Take Nine Elms, for example, a massive, multi-billion-pound regeneration project on the southern bank of the Thames in London. With its lush new Nine Elms Park – a 2.5-acre public green space whose first section opened in 2023 with more currently under construction – and a host of other green and blue spaces sprinkled in, it appears at first glance as a green utopia of sorts and an exciting model for sustainable urban living. However, the social realities underlying the project are far less idyllic. Nine Elms, which, when completed, will comprise around 20,000 homes and millions of square feet of office, leisure, and retail space, has been heavily criticised for primarily catering to wealthy investors, including many from overseas, rather than addressing local needs. While London battles a severe housing crisis – with Lambeth, where most of Nine Elms is located, having the most extended waiting list of any UK authority last year – the project itself includes almost no housing options that are genuinely (!) affordable. Adding insult to injury, the news that those fortunate enough to secure one of the few below-market-rate homes often face the indignity of having to use "poor doors", segregating them from their wealthier neighbours, only reinforces the widespread perception that the project was not designed with ordinary Londoners in mind.

With its abundant landscaping, it is easy to miss what Nine Elms represents - not so much a utopian as, in many ways, a somewhat dystopian vision of urban life. A place that is curated and controlled, dominated by high-end developments that prioritise capital, not people, and that readily sacrifices social inclusion for exclusivity. And it is now, as large parts of Nine Elms reach completion, increasingly difficult to envision what this central part of London, now irreversibly transformed by its "turbo-charged speculative development", could have become: a truly inclusive and sustainable neighbourhood that is both green and fair.

It boils down to this: the property industry’s growing enthusiasm for so-called "green premiums" – additional costs that buyers and renters are willing to pay for environmental features like green spaces – may be understandable from a business perspective. However, from the standpoint of community-oriented and equitable urban development, this trend is an affront and underscores how much work there remains to be done to realise the vision of "green cities for all." In London, as in other cities, well-provisioned – and maintained – green spaces are to this day predominantly found in affluent neighbourhoods, while those from lower socioeconomic and ethnic minority backgrounds tend to have less access to them. This gap needs to close and for it to close, treating them – or any other environmental benefit for that matter – as an upsell, a luxury, and as an asset for profit generation does not help.