Guidelines for a 'depaving' and 'regreening' strategy in cities. REGREEN deliverable D3.2

The loss of soil functions and ecosystem services is one of the major environmental challenges Europe is facing. Despite a reduction in the last decade, land take in EU28 still amounted to 539km2/year between 2012‐2018. Since the mid‐1950s, the total surface area of cities in the EU has increased by 78% while the population has grown by just 33% [1]. Population growth can also drive land take, but built‐up areas are expanding more quickly than populations are growing. Urban sprawl often continues even where populations are decreasing. In France, the rate of land take in France is the highest in Europe, occurring 4 times faster than population growth. This phenomenon is now foremost among the drivers of rapid climate change and the erosion of biodiversity [2].
To address this global problem, the European Commission has proposed in the EU Environment Action Programme to 2020 (7th EAP) to achieve ‘no net land take’ by 2050. Sealing agricultural land and open spaces should be avoided as far as possible and the focus should be on building on land that has already been sealed. In France, the national objective dubbed Zéro Artificialisation Nette (Net Zero Land Take) marks a turning point in strategies designed to slow urban sprawl as it places the emphasis on urban renewal and densification. It also introduces a renaturing goal that involves “giving back to nature” an amount of land equivalent to that consumed by urban growth. For example, unused land could be returned to cultivation or renaturalised so that it can once again provide the ecosystem services of unsealed soils. The implementation of the Net Zero Land Take goal, however necessary it may be, may nevertheless result in even greater urban densification in cities that are already suffering from climate change and dwindling biodiversity. Moreover, the estimated cost and complexity of a renaturing operation above all presuppose the avoidance of any additional land take.

In this context, slowing urban growth and renaturing urban environments have become key strategies. They are all the more relevant as biodiversity is declining significantly in urban areas, the effects of climate change (runoff, flooding, urban heat islands, etc.) are intensifying and the health and wellbeing of city‐dwellers are deteriorating. Renaturing makes it possible to adapt cities to climate change and to make them more permeable to wildlife by developing nature‐based solutions. Our cities are full of areas that have been concreted or asphalted over and where nature could return and flourish. The Paris Region, especially the Greater Paris area, is particularly affected by the consequences of urbanisation and density. The purpose of this guide is to propose a method that will help local authorities to target urban areas where renaturing represents a key strategy to restore biodiversity, adapt to climate change and improve people’s health. Based on feedback from respondents in the field, it provides recommendations on how to implement projects in the best possible conditions.

This guide is part of the European project titled Horizon 2020 REGREEN on nature‐based solutions in urban environments. The term “nature‐based solutions” refers to initiatives aimed at the conservation, management and restoration of ecosystems. Their aim is to attenuate climate change (e.g. via carbon capture and storage) and to facilitate adaptation to climate change (e.g. via protection against storms, flooding and landslides). These solutions have proved their effectiveness and can complement or replace the grey infrastructure traditionally used in regional development. The advantage of nature‐based solutions is that they are multi‐functional whereas grey solutions only solve one problem at a time. As well as benefiting climate and biodiversity, they have the advantage of helping to improve the living environment and health of city‐dwellers at lower cost to local authorities. Nature‐based solutions apply to all environments on all scales (farmland, woodland, aquatic and urban environments) and help enhance the resilience of local regions to global change. Renaturing is a way of rolling out nature‐based solutions in areas that have been subject to land take and ground sealing.