As the 25th anniversary of the Rio Earth Summit comes around, it is hard to believe that just a quarter of a century ago cities were at the margins of the sustainability agenda. Long-standing traditions of nature conservation which positioned cities as a threat to the environment and the growing interest in the global dimensions of environmental change left little space for thinking of urban sustainability.

1992 was a turning point in this story. Thanks to the pioneering work of ICLEI and others advocating the importance of local action, cities grabbed a foothold in Agenda 21 and haven’t looked back since. From this small corner of global politics, the role of cities in responding to sustainability challenges has grown and grown. Whether it is about reducing vulnerability, mitigating climate change, protecting biodiversity or improving well-being, cities have become firmly established as essential for achieving sustainability.

The Sustainable Development Goals agreed by the global community have cemented the importance of cities in responding to challenges as diverse as reducing disaster risk to providing access to green space. Cities have individually and collectively taken significant steps towards these goals, with the most recent formation of the Global Covenant of Mayors for Climate Change and Energy demonstrating their ambition to be at the forefront of this agenda.

Yet as cities have started to implement plans for sustainability and to experiment with responses, the complex, interlinked and often intractable nature of the challenges they face has become ever more apparent. Existing approaches designed for traditional forms of urban development – from infrastructure provision to building design, mobility to well-being – need to be rethought. Searching for new solutions, there has been a growing interest in how to use nature to turn urban challenges into innovation opportunities.

Nature-based solutions has become the umbrella term to describe these “solutions to societal challenges that are inspired and supported by nature”. Examples include forms of green infrastructure, wildflower planting to encourage pollinators on urban verges (Guardian), community participation in the management of municipal parks, and water retention schemes.

Nature-based solutions are imagined as multi-functional – addressing multiple urban challenges and providing ecological, economic and social benefits. They are often thought to be more cost-effective and to be able to adapt to changing environmental conditions to offer long-term resilience.

If 25 years ago we turned to cities to help us save nature, now it seems cities are turning to nature to help save themselves. As cities start to innovate with nature-based solutions, the NATURVATION project will be assessing the contribution that such solutions can make, finding out works to support innovation in cities, and working with partners across Europe and internationally to create the knowledge and tools needed to realise the potential of nature to make our cities more sustainable.

Harriet Bulkeley is Professor of Geography at Durham University and Co-ordinator of NATURVATION