Imperviousness and imperviousness change in Europe
Imperviousness negatively affects biodiversity, carbon storage and sequestration, soil hydrological properties, ecosystem services and nature conservation. In 2018, the sealed area in the European Union Member States was 110,702km2 (2.7%). The increase in this area was 3,606km2 (3.4%) between 2006 and 2018. The largest sealing increase of 1,156km2 during 2009-2012 fell to half during 2012-2015, yet picked up again from 2015 to 2018 (796 km2). Although most sealing happened in settlements, sealing in cropland was also substantial with 1,383km2 agricultural area sealed from 2006 till 2018.
Figure 1. Imperviousness increase by land use category in EU-27
Imperviousness is the sealing of land with impermeable materials like asphalt and concrete. The continuing rapid expansion of sealed surfaces is often improperly planned and unjustified by population's needs. Sealing hampers nature’s ability to deliver a wide range of environmental, climate change adaptation and biodiversity benefits.
The European Commission’s roadmap to a resource efficient Europe introduced a ‘no net land take by 2050’ initiative, which aims to ensure that all new urbanisation occurs on brownfields or any new land take is compensated for by reclaiming artificial land. Land take and sealing are also relevant to several targets of the EU biodiversity strategy for 2030, aimed at protecting and restoring nature. Sealing also affects the implementation of the EU strategy on green infrastructure and long-term objectives of the common agricultural policy (CAP), such as viable food production, the sustainable management of natural resources, climate action and balanced territorial development.
In 2018, 110,702km2 (2.7%) of soil was sealed in the 27 Member States (dashboard), approximately the size of Bulgaria. Sealed croplands reached 40,287km2 by 2018, almost the size of the Netherlands, and just 6,000km2 less than sealed surfaces in settlements. Sealing of forests (vital sources of food, fibre, habitats and important carbon sinks) and grassland ecosystems (critical for biodiversity and ecosystem services) reached 12,800km2 and 10,347km2 respectively.
From 2006 to 2018, the increase in sealed area was 3,606 km2, up 3.4% from 2006 (dashboard). The largest increase of newly sealed land was 1,156km2 during 2009-2012. This fell by half during 2012-2015 (576km2) and picked up again during 2015-2018 (796 km2).
New sealing dominated settlements during all four observation periods (figure 1), contributing to the development of urban heat islands, floods and impacts on human health. This is no surprise, as sealing is driven by socio-economic factors such as the demand for new homes, industrial buildings, and infrastructure.
Considering their role in Europe’s labour, food and fibre production, carbon sequestration, and biodiversity maintenance, it is highly alarming that significant sealing occurred in croplands. While sealing in croplands was lowest from 2012 to 2015, it increased again during 2015-2018, reaching 305km² of new sealing. Over the 12 years, 1,383 km2 of croplands were sealed in total. Sealing in forests, grasslands and wetlands together amounted to 656km2 for the whole period, yet only reaching 37km2 in wetlands.
Figure 2. Imperviousness in 2006 and imperviousness increase during 2006-2018 in the EEA-38
Among all 38 EEA member states (Figure 2), the largest sealing increase during 2006-2018 was in Cyprus (11% compared to 2006). For the EU-27, Poland’s sealing increase was the second largest, yet only amounting to half of the increase in Cyprus. Poland’s 2006 sealed surface was only 2.4% of the country, compared to almost 4% in Cyprus.
Larger sealing increase in other EU countries remained under 5% (Malta 4.6%, Slovakia 4.8%, Spain 4.9%), although Malta had the largest sealing in 2006 of all Member States (17% of the country) (dashboard). Sealing increase was less than 4% in the Netherlands and Belgium, however their 2006 sealing level was almost 10% of the country, very high among Member States. Latvia and Lithuania increased soil sealing the least (less than 2%) and were amongst the lowest in 2006 (less than 2% of the country).
Türkiye and Kosovo lead sealing increase for the non-EU countries with an 8% increase compared to 2006, but their 2006 sealing was relatively low, 1% and 2% respectively. Iceland also scored relatively high with a 6.8% increase in sealing, but their level in 2006 was the lowest in the EEA member countries, with 0.1% of their territory.
Supporting information
The imperviousness indicator measures the covering of the soil surface with non-permeable materials, hence indicating imperviousness. The indicator addresses the change in the areas of sealed land per LULUCF land use categories every three years in the period 2006-2018.
For indicator calculation
Even though Copernicus Land Monitoring Service (CLMS) products are the best available datasets to monitor soil sealing over Europe, the 2018 Imperviousness Degree (IMD) layer was produced on a 10m spatial resolution taking advantage of the availability of Sentinel 2 data, whereas earlier layers are provided on 20m resolution. Unfortunately, the upgrade to 10m from 20m spatial resolution has resulted in a break in the IMD based areal statistics; the 20m resolution IMD time-series (2006-2009-2012-2015) was successfully harmonized by the CLMS and have shown a credible evolution in sealed cover. The IMD2018 dataset exhibits significantly more sealed structures than previous layers, thus the amount of sealed cover is showing an unrealistic growth compared to former status. In addition, the CLMS has been producing a new dataset from 2018 onward entitled the CORINE Land Cover (CLC)+ Back Bone raster which also include a sealed area thematic class. When comparing the IMD and CLC+ Backbone Raster datasets with sampled reference data, it appears that the imperviousness dataset substantially underestimates sealed areas at European level. The CLC+ dataset only started to be available from 2018 and currently does not include any change layer. To address these issues, a combined, harmonized and bias-corrected soil sealing dataset for Europe was produced by the EEA for the entire observation period.
For the geometric harmonisation of the CLMS IMD time series for 2006, 2009, 2012, 2015 and 2018 the following steps were used:
1. Create Sealed 2018 status by extracting class 1 from CLC+ Backbone 2018 (10m) (set all other classes to 0);
2. Create the Sealed 2015 accounting status layer by combining Sealed 2018 status with IMCC1518accounting:
a. Resample 20m resolution IMCC1518accounting to 10m resolution;
b. Combine IMCC1518accounting sealing increase with Sealed 2018 status: IF Sealed 2018 status is sealed (value=1) and IMCC1518accounting is class “new cover” THEN write new Sealed 2015 accounting status layer with value “unsealed” (unsealed=0) at corresponding grid cell;
c. Combine IMCC1518accounting sealing decrease with Sealed 2018 status: IF Sealed 2018 status is not sealed (value=0) and change is “loss of cover” THEN write new Sealed 2015 accounting status layer with value “sealed” (sealed=1) at corresponding grid cell;
d. For the rest of the pixel copy the values (sealed/unsealed, i.e. 1/0) from the Sealed 2018 status layer.
3. Create the Sealed 2012 accounting status layer by combining Sealed 2015 status with IMCC1215:
a. Resample 20m resolution IMCC1215 to 10m resolution;
b. Combine CLMS IMCC1215 sealing increase with Sealed 2015 accounting status: IF Sealed 2015 accounting status is sealed (value=1) and CLMS IMCC1215 is class “new cover” THEN write new Sealed 2012 accounting status layer with value “unsealed” (unsealed = 0) at corresponding grid cell;
c. Combine CLMS IMCC1215 sealing decrease with Sealed 2015 status: IF Sealed 2015 status is not sealed (value =0) and change is “loss of cover” THEN write new Sealed 2012 status layer with value “sealed” (sealed=1) at corresponding grid cell;
d. For the rest of the pixel copy the values (sealed/unsealed, i.e. 1/0) from the Sealed 2015 status layer.
4. Create the Sealed 2009 accounting status layer by combining Sealed 2012 status with IMCC0912:
a. Resample 20m resolution IMCC0912 to 10m resolution;
b. Combine CLMS IMCC0912 sealing increase with Sealed 2012 accounting status: IF Sealed 2012 accounting status is sealed (value=1) and CLMS IMCC0912 is class “new cover” THEN write new Sealed 2009 accounting status layer with value “unsealed” (unsealed = 0) at corresponding grid cell;
c. Combine CLMS IMCC0912 sealing decrease with Sealed 2012 status: IF Sealed 2012 status is not sealed (value =0) and change is “loss of cover” THEN write new Sealed 2009 status layer with value “sealed” (sealed=1) at corresponding grid cell;
d. For the rest of the pixel copy the values (sealed/unsealed, i.e. 1/0) from the Sealed 2012 status layer.
5. Create the Sealed 2006 accounting status layer by combining Sealed 2009 status with IMCC0609:
a. Resample 20m resolution IMCC0609 to 10m resolution;
b. Combine CLMS IMCC0609 sealing increase with Sealed 2009 accounting status: IF Sealed 2009 accounting status is sealed (value=1) and CLMS IMCC0609 is class “new cover” THEN write new Sealed 2006 accounting status layer with value “unsealed” (unsealed = 0) at corresponding grid cell;
c. Combine CLMS IMCC0609 sealing decrease with Sealed 2009 status: IF Sealed 2009 status is not sealed (value =0) and change is “loss of cover” THEN write new Sealed 2006 status layer with value “sealed” (sealed=1) at corresponding grid cell;
d. For the rest of the pixel copy the values (sealed/unsealed, i.e. 1/0) from the Sealed 2009 status layer.
For further processing the time series was converted to 1km grid size which was the best compromise in terms of reporting on sealed soil surface and available resources. In the next step a visually interpreted reference database was created, where within 1kmx1km primary sampling units (PSUs) 100 secondary sampling units (SSUs) were selected on a regular grid. With a non-linear regression estimate a relationship was established between the visually interpreted ground truth and the 1km harmonised layers. The regression estimate was applied to the harmonised layers and a new 1km harmonised and corrected time series was created.
Sustainable soil management and soil protection measures facilitate the removal of excess atmospheric carbon into the soil. The main policy-relevant objective of this indicator is to measure the extent and dynamics (change) of soil sealing, resulting from the development of urban and other artificial land. Coordinated action at EU level is expected to generate synergies, effectiveness and efficiency gains for ensuring that soils are managed in a sustainable way. Coordinated action is also expected to address climate change, reverse biodiversity loss, aim at zero pollution and achieve land degradation neutrality. The transition of the EU to a fair and prosperous society will need to take into account the protection and sustainable use of soils as a key aspect for the future sustainability.
The European Green Deal (EGD) ("The European Green Deal", European Commission, 2019) aims at implementing a set of ambitious measures across sectors in Europe to undergo a sustainable green transition and becoming the first climate-neutral continent by 2050 (European Council, 2019). It provides an overarching framework for the implementation of many environmental and climate related targets in key areas.
The first European Climate Law entered into force on 29 July 2021 with a legal objective for the Union to reach climate neutrality by 2050. The European Climate Law supports the need to enhance the EU's carbon sink through the Regulation on Emissions from Land Use, Land Use Change and Forestry (LULUCF), for which the Commission made a proposal in July 2021 as part of the “Fit for 55 Package”. This new proposal for a LULUCF Regulation extends the scope from only forests to all land uses. There is an indirect link to soil protection as reducing emissions may imply changes to soil management practices or selection of soil management options.
The EU Adaptation Strategy (COM(2013)216) provides an overarching framework for adaptation through different voluntary mechanisms. There is no mandatory requirements for action on soil protection but the aim is to increase national adaptation strategies which will include soil protection aspects. The adaptation strategy has a link to protection of carbon rich soils and management that promotes SOM retention and other associated soil quality benefits. Directly links to SOM levels in particular reducing loss of SOM, but also accumulation in agricultural soils
The "EU Soil Strategy for 2030 – Reaping the benefits of healthy soils for people, food, nature and climate" of November 2021 shows the way to the future handling of the so far neglected environmental medium soil. The EU Soil Strategy is a key deliverable of the EU biodiversity strategy for 2030 and sets out a framework and concrete measures to protect and restore soils, and ensure that they are used sustainably. It sets as well a vision and objectives to achieve healthy soils by 2050, with concrete actions by 2030. Monitoring soil sealing is also complementary to other measures outlined in the Biodiversity Strategy 2030 (e.g. nature restoration) and in the EU Soil Strategy (such as the guidance on risk assessment, soil sealing and funding). Both the Biodiversity strategy and the Soil Strategy to 2030 include the "No-Net Land Take" target by 2050. The Soil Strategy also addresses land recycling and promotes the circular use of land over greenfield development to limit the acute pressure from soil sealing and land take.
On the global level, the IPCC's special report on climate change and land identified increased soil organic carbon as one of the most cost-effective options for climate change adaptation and mitigation, as well as for combating desertification, land degradation and food insecurity. At the United Nations Conference on Sustainable Development held in Rio in 2012 (Rio+20), world leaders identified land and soil degradation as a global problem and committed to ‘strive to achieve a land degradation-neutral world in the context of sustainable development’. At the EU level, the 8th Environment Action Programme (8th EAP) includes a strong focus on the unsustainable use of land and soil, including the issue of soil sealing explicitly. In this context, the 7th EAP refers to the Commission Staff Working Document ‘Guidelines on best practice to limit, mitigate or compensate soil sealing’.
‘No net land take’ is also addressed in the land degradation neutrality (LDN) target of the United Nations Convention to Combat Desertification (UNCCD), which aims to maintain the amount and the quality of land resources. LDN is promoted by target 15.3 of the UN Sustainable Development Goals (SDGs), which, by 2030, strives to combat desertification and to restore degraded land and soil. Land and soil are also linked to goals that address poverty reduction (SDG 1), health and well-being through reduced pollution (SDG 3), access to clean water and sanitation (SDG 6), the environmental impact of urban sprawl (SDG 11) and climate change (SDG 13).
Targets
While many EU and national policies address land and soil to some extent, legally binding targets, incentives and measures are largely missing at the EU level. Nevertheless, the 8th Environmental Action Programme and the Soil and Biodiversity Strategies to 2030 all address land take and aim at No-Net Land Take by 2050.
Methodology uncertainty
The methodology is based on modelling soil sealing time series onto a 1km grid using visually interpreted ground truth data and a soil sealing time series with geometry harmonisation, derived from the Copernicus Land Monitoring Service Imperviousness time series.
Data sets uncertainty
Large-scale sealed surfaces or land use processes converting semi-natural land to artificial surfaces will be underestimated in the modelled 1km dataset and hence the real sealing value could be higher. The total sealed area extracted from the harmonized Imperviousness time series for Europe is within the 95% confidence interval of the CLMS estimates produced from the CLMS imperviousness validation data gathered for the data production.
