Reducing street parking can free up large areas for urban nature

Abstract Nature-based solutions (NBS) are increasingly recognised as a means to address critical urban sustainability problems such as heatwaves, flooding and biodiversity loss. Accordingly, cities around the world have committed to ambitious targets for urban greening. Meeting these targets will require large areas of land to be converted from existing uses to green space. However, finding this land is difficult in established urban areas, where space is already strongly contested. Here we show an approach by which cities can make substantial progress towards a range of sustainability targets: by converting redundant street parking into biodiverse green space. Significant areas of public land in dense cities are currently allocated to street parking, while off-street parking garages in urban areas are typically abundant and have high rates of vacancy. We demonstrate that vacancy in off-street garages is so substantial that up to half of street parking in our case study municipality (The City of Melbourne, Australia) could be accommodated in garages within 200 m, freeing up large areas for conversion to green space. Our modelling shows this would have significant benefits in terms of tree canopy cover, stormwater treatment and ecological connectivity in the city. These benefits would represent strong progress towards – and even meet – a number of the city’s ambitious NBS targets. As many cities allocate extensive areas to both street parking and off-street garages, this approach to freeing up space for nature in cities is widely applicable. Our findings indicate this is a practical means for municipalities with the required political will and public support to deliver their sustainability goals.