Net Zero Land Development: An Analysis of the Issues

On July 21, two decrees amending the ZAN (Zero Net Artificialization) Act were published in the Official Journal, thereby modifying its implementation. This marks the final step in a long and complex legislative process to implement a commitment announced in the 2018 Biodiversity Plan. What exactly are we talking about? Will the law make it possible to achieve the goals set by the government to reduce land conversion in France?

Carbone 4 offers an in-depth analysis of the ZAN law, the challenges surrounding land sealing in France, and its impact on greenhouse gas (GHG) emissions, biodiversity, and the well-being of our society.

How can we define land-use change?

According to the INSEE definition generally used in institutional documents, land sealing refers to the transformation of natural, agricultural, or forested areas (ENAF) in man-made areas, through development projects that could lead to their partial or complete waterproofing.

In practice, land-use change is generally poorly defined. It can encompass very different realities depending on the areas in question, the type of land use change, and, consequently, the associated impacts: converting a diverse forest into a paved parking lot or an area of intensive agriculture into a green urban park obviously does not have the same environmental consequences. Similarly, according to this definition, an area considered “unartificialized” is not necessarily environmentally beneficial: an area of intensive agriculture that uses large quantities of inputs and pesticides, for example, will be counted among the ENAFs, i.e., as “unartificialized” land, despite having a significant impact on living organisms. It is important to note that this concept ofland-use change Therefore, it does not allow for a distinction between human-altered and natural areas, nor between areas that are beneficial and those that are harmful to biodiversity. Nor is it synonymous with soil sealing: in France, approximately two-thirds of artificialized soils (non-ENAF) are considered to be sealed. (Source: Agreste, Investigations by Teruti Lucas, 2014 see Primeur No. 326)

The The methods used to assess this land-use change are also very diverse, resulting in widely varying estimates. Depending on the sources and the periods studied, these figures can range from 16,000 to 61,200 ha per year ^[1], with implications for the ambition of the announced targets. Regardless of the estimates, The data, however, consistently show that “in France, land conversion exceeds the European average and is increasing faster than the population.” ", as analyzed by the authors of the report on the ZAN objective produced by France Stratégie in 2019 ^[2].

In fact, with an average of 446 m² of land converted to artificial surfaces per person, France ranks fourth among European countries with the highest rate of land conversion per capita. Since 1981, the amount of land converted to artificial surfaces has risen from 3 to 5 million hectares (+70%), a rate of growth far exceeding that of the population (+19%). Five million hectares is equivalent to the total area of the Bourgogne-Franche-Comté region. Between 2009 and 2019, approximately 276,000 hectares of land were developed in metropolitan France, which is the equivalent, in just 10 years, of the Rhône department.

The land affected by this land-use conversion is primarily agricultural. It is converted for residential purposes (42%), transportation (28%), or service and recreational infrastructure (16%), similar to commercial areas^[3]. Among the causes of the acceleration of land conversion In France over the past few decades, examples include urban sprawl and the underutilization of existing buildings^[4], the increase in the number of households, and new consumption patterns. According to the Land Use Change Observatory, 43% of land use occurs in low-density peri-urban areas.

What are the consequences of land development?

Land-use changes have significant impacts on our environment, contributing to the climate crisis and the loss of biodiversity. The nature and severity of these impacts depend both on the type of developed areas created (more or less impervious, more or less vegetated, etc.) and on the quality of the soil in the areas consumed during the process (types of agricultural land and management practices). Given the overall trends in France, several major consequences associated with land development are observed within the territory.

Biodiversity

Land-use change is the the leading cause of the loss of terrestrial biodiversity worldwide^[5]. Although it lags far behind agricultural expansion in terms of land area, land development is nonetheless one of the forms of land-use change that has the greatest impact on ecosystem integrity.  Tilling the soil and its potential sealing significantly disrupt soil microorganisms and fauna. The affected ecosystems and the species living in these environments are also significantly impacted, whether through the direct destruction of habitats, the fragmentation of ecosystems, and the disruption of ecological connectivity, or through disturbances and pollution associated with human activities. The habitats of certain species may become too small to remain viable; certain infrastructure can act as barriers preventing movement from one natural area to another (e.g., roads, railroads, dams, etc.), isolating populations or leading to increased direct mortality when certain animals attempt to cross them; similarly, light and noise pollution can disturb and cause the displacement of many species.

Land-use change, through the direct and indirect impacts mentioned above, contributes to thethe decline or even collapse of the species that lived in these areas. Another consequence to consider isthehomogenization of living organisms (which also leads to a decline in biodiversity) if only a few species that can tolerate the living conditions of artificial environments survive there, to the detriment of others.

It should be noted that areas considered “undeveloped” but subject to intensive agricultural or forestry practices can have similar consequences for biodiversity (habitat destruction and fragmentation).

Carbon

In terms of GHG emissions, land-cover change is a source of CO2 emissions, but also a potential cause of reduced carbon sequestration capacity in ecosystems. Its impact on climate change is therefore significant. Nationwide in France, land-use change is responsible for approximately 5 million metric tons of CO2 in 2022 (2023 HCC report), representing 8% of emissions from the building sector.

When vegetation is removed and the soil is disturbed, the carbon that was stored in the soil is released into the atmosphere, especially if the soil is not quickly covered by vegetation or a suitable surface. According to ADEME, approximately 190 tCO2 are emitted when one hectare of farmland is converted into an impervious surface—the equivalent of the annual carbon footprint of 20 average French people. Although the estimates are subject to a high degree of uncertainty, it is clear that the impact in terms of CO₂ emissions depends on the type of land conversion: sealing permanent grasslands emits 50% more CO2 than sealing cropland (290 metric tons of CO2 vs. 190 metric tons of CO2).

Land-use change, and in particular the sealing of surfaces, further reduces the carbon sequestration potential of French soils. How, then, can we achieve the goal of carbon neutrality by 2050 (a balance between emissions and carbon sinks) if the absorption capacity of current carbon sinks is declining?

Finally, since land development is the first step in establishing new activities (housing, transportation, infrastructure, etc.) on land that was previously ENAF, it is indirectly linked to the emissions from the future activities that will be carried out there. It is therefore crucial to consider the end use of developed land and the need that the project addresses in order to assess whether it contributes to achieving France’s carbon neutrality goals or, conversely, whether it hinders the achievement of that goal.

It should be noted that the impacts of land-use change do not only affect biodiversity and carbon, but can also have adverse effects on other environmental and social factors:

• The local climate, due to the amplification of the urban heat island effect
• Water management in the case of impervious surfaces: By definition, water is no longer absorbed into the soil and instead runs off the concrete, increasing the risk of flooding, soil erosion, and waterborne pollution
• Quality of life: Urban sprawl can affect residents’ quality of life and exacerbate inequalities and social division, as longer distances between home and workplaces and daily destinations lead to increased transportation costs and travel time.

Toward Net Zero Land Conversion by 2050?

The 2018 Biodiversity Plan included the goal of Zero Net Land Conversion (ZAN) in the government’s commitments for the first time. It was not until the Climate and Resilience Act of August 22, 2021—following the Citizens’ Climate Convention—that a precise definition of this goal was established. This law sets an ambitious goal for France by requiring a 50 percent reduction in land consumption by 2030 (i.e., reducing land conversion from 250,000 hectares between 2011 and 2020 to 125,000 hectares between 2021 and 2030), in order to achieve Net Zero Land Development (ZAN) by 2050. ZAN corresponds to the balance^[6] between additional land-converted areas—which lose their natural functions to accommodate human activities—and “renaturalized” lands.

The law defines land conversion as “the permanent alteration of all or part of a soil’s ecological functions—in particular its biological, hydrological, and climatic functions—as well as its agronomic potential, through its occupation or use. ” The ZAN objective thus leads us to view soil as a natural resource that provides ecosystem services and must be preserved.

This is in line with the various European and international policies. At the European level, it is worth noting the goal of “no net land take by 2050,” adopted in 2013 and subsequently reinforced and expanded upon by the Biodiversity Strategy to 2030 and the Soil Protection Strategy adopted in 2023 by the European Commission. The Nature Restoration Act (adopted by Parliament in July 2023 and currently in the trilogue phase) is part of this overall strategy, endorsing the goal of restore 20% of the Earth's land area and marine ecosystems by 2030 and to restore all “poor to bad quality” ecosystems by 2050.

Implementing the ZAN requires a fundamental rethinking of our land-use planning model, based in particular on a cooperative approach and an unprecedented need for coordination among local authorities. The goal is to replace a model based on land consumption and urban sprawl with one based on land-use efficiency, while maintaining a commitment to supporting the development of all French regions in order to reduce regional inequalities.

In practical terms, compliance with the ZAN depends on the incorporation of land-use conversion targets into planning and urban development documents. Local governments are therefore responsible for the implementation and success of the ZAN, particularly through the creation of a new regional-level body tasked with ensuring compliance with these targets. This body is also tasked with facilitating any necessary trade-offs when the total projected land conversion in local planning documents (PLU, PLUi) exceeds the region’s targets.

That said, the governance of the ZAN faces major challenges, both political and technical. On the political front, many elected officials oppose it on the grounds that the ZAN is incompatible with their development plans and efforts to enhance regional attractiveness. This political opposition is a major obstacle that risks making it difficult to achieve a real reduction in land consumption in France, given that numerous exemptions have already been incorporated into the legislation and implementation deadlines have been delayed as a result of political battles. From a technical standpoint, the issue of measuring land artificialization remains a central concern that has not yet been sufficiently well defined to ensure its inclusion in urban planning documents—as illustrated by the Council of State’s decision regarding the lack of precision in the definition of artificialized areas (decision handed down on October 4, 2023).

The ongoing difficulties in implementing the ZAN across the regions suggest that the government has not allocated sufficient resources to ensure its success. Placing the entire burden of the initiative on local governments seems to overlook the significant role that businesses could play in reducing land development if they were required to do so.

This may be one of the shortcomings of current government goals: How can we engage businesses in achieving net zero land conversion? When choosing to establish a presence in a region or to develop economic activities there, businesses are increasingly aware of their responsibility in those regions in terms of social cohesion, economic development, health, and the climate. This responsibility should also extend to land-use issues in order to encourage economic actors to engage in dialogue with local governments and work together to reduce land-use changes.

Conclusion

Although the goal of “Zero Net Land Conversion” is ambitious and aligns with France’s climate and biodiversity objectives, its operational implementation is still far from assured. What land-use planning strategies can be implemented to achieve this goal?

The cooperation required for the ZAN’s success presents a unique opportunity to rethink how we shape our landscape and our construction practices, moving toward more land-efficient development. That said, the ZAN highlights what may appear to be an inconsistency in our response to environmental challenges, requiring us to reduce land development while continuing to meet the imperatives of regional development and reindustrialization (road, infrastructure, and housing projects, etc.). To address these two challenges, local governments must develop an engineering approach that allows them to consider the territory as a whole (incorporating issues of biodiversity, mitigation, adaptation, development, well-being, etc..). Solutions may then emerge, such as the development of small properties (small plots with vacant land), which are scattered but numerous and often well-located, or the use of urban brownfields (commercial, military, and industrial).

The Limits of the “Balance” Principle Underlying the ZAN and the Renaturation Objectives

Based on the concept of balance, the long-term goal of “zero net land-use change” also relies on efforts to reverse land-use changes, or to restore natural conditions. As defined by the Climate and Resilience Act, the renaturation of land consists of “actions or operations to restore or improve the functionality of land, with the effect of transforming artificial land into natural land.” Thus, beyond reducing land conversion, improving soil quality—particularly with regard to its carbon storage capacity—is essential for conserving and restoring the various ecosystem services provided by soils.

When it comes to achieving carbon neutrality in France and developing our carbon sinks, the ZAN is a necessary but insufficient approach to increasing the potential of carbon sinks. Yet this increase is essential, as the latest report from the High Council for Climate, published in October 2023, reminds us.

This raises the question of France’s actual capacity for renaturation: Which areas have genuine potential for renaturation, and how can we ensure the effective implementation of renaturation projects? Here again, local governments are on the front lines when it comes to designing and carrying out restoration projects that help meet the ZAN objective.

For now, the lack of information on our ability to restore soils on a large scale suggests that we will soon need to question the relevance of a “zero gross land-take” policy—that is, a complete halt to the consumption of undeveloped land.