Soil moisture (CLIM 029) - Assessment published Nov 2012
- Soil water retention is a major soil hydrological property that governs soil functioning in ecosystems and greatly affects soil management.
- There is no clear indication on past trends for water retention across the EU due to a lack of systematic and harmonised data.
- Water retention capacity and soil moisture content will be affected by rising temperatures and by a decline in soil organic matter due to both changes in climate and land management.
- Projections (for 2071–2100) show a general reduction in summer soil moisture over most of Europe, significant reductions in the Mediterranean region, and increases in the north-eastern part of Europe.
- Maintaining water retention capacity and porosity are important to reduce the impacts of intense rainfall and droughts, which are projected to become more frequent and severe.
How are soil moisture and water retention capacity changing in Europe?
Global surface soil moisture content based on remote sensing data
Note: SMOS provides a global image of surface soil moisture every three days; this map covers the period 8–15 June 2010. Yellow colours indicate drier soil surfaces; blue colours denote wetter conditions. SMOS can measure soil moisture levels to an accuracy of 4 % at a spatial resolution of 50 km — about the same as detecting a teaspoonful of water mixed into a handful of dry soil.
- Soil moisture and ocean salinity provided by European Space Agency (ESA)
There is no clear indication on past trends for water retention across the EU due to a lack of systematic and harmonised data. Several models have been used to assess soil moisture, but these are often reliant on secondary input data (i.e. observed precipitation and temperature). Direct observations of spatially explicit distribution of soil moisture across Europe are just evolving. Satellite-borne sensors, such as the European Space Agency’s (ESA) Soil Moisture and Ocean Salinity (SMOS) mission or EUMETSAT’s ASCAT Scatterometer, are able to make global observations of surface soil moisture (Figure 1). Such data, along with numerical modelling techniques, have the potential to be used in deriving composite maps of soil moisture levels down to a depth of 1–2 m, the so-called root zone. Thus, this information could help in assessing the impacts of climatic variations, including droughts, on for example ecosystem production.
Projections indicate greater droughts in some areas, which might lead to substantial reductions in summertime soil moisture, and marked increase in rainfall in others [i]. In particular in the Mediterranean area of southern Europe, soil water content is expected to decline, and saturation conditions are expected to be increasingly rare and restricted to periods in winter and spring [ii]. Harmonised time series data on relevant soil properties should be developed as should models to assess key parameters such as subsoil available water capacity and topsoil moisture levels. Satellite information should be integrated with representative observed data, also for projections.
[i] P. Calanca et al., „Global warming and the summertime evapotranspiration regime of the Alpine region“, Climatic Change 79 (2006): 65–78, doi:10.1007/s10584-006-9103-9.
[ii] José M. García-Ruiz et al., „Mediterranean water resources in a global change scenario“, Earth-Science Reviews 105, Nr. 3–4 (April 2011): 121–139, doi:10.1016/j.earscirev.2011.01.006.
Indicator specification and metadata
- Global surface soil moisture content based on remote sensing data
Policy context and targets
In April 2013 the European Commission presented the EU Adaptation Strategy Package (http://ec.europa.eu/clima/policies/adaptation/what/documentation_en.htm). This package consists of the EU Strategy on adaptation to climate change /* COM/2013/0216 final */ and a number of supporting documents. One of the objectives of the EU Adaptation Strategy is Better informed decision-making, which should occur through Bridging the knowledge gap and Further developing Climate-ADAPT as the ‘one-stop shop’ for adaptation information in Europe. Further objectives include Promoting action by Member States and Climate-proofing EU action: promoting adaptation in key vulnerable sectors. Many EU Member States have already taken action, such as by adopting national adaptation strategies, and several have also prepared action plans on climate change adaptation.
The European Commission and the European Environment Agency have developed the European Climate Adaptation Platform (Climate-ADAPT, http://climate-adapt.eea.europa.eu/) to share knowledge on observed and projected climate change and its impacts on environmental and social systems and on human health; on relevant research; on EU, national and subnational adaptation strategies and plans; and on adaptation case studies.
No targets have been specified.
Related policy documents
Climate-ADAPT: Mainstreaming adaptation in EU sector policies
Overview of EU sector policies in which mainstreaming of adaptation to climate change is ongoing or explored
Climate-ADAPT: National adaptation strategies
Overview of activities of EEA member countries in preparing, developing and implementing adaptation strategies
DG CLIMA: Adaptation to climate change
Adaptation means anticipating the adverse effects of climate change and taking appropriate action to prevent or minimise the damage they can cause, or taking advantage of opportunities that may arise. It has been shown that well planned, early adaptation action saves money and lives later. This webportal provides information on all adaptation activities of the European Commission.
EU Adaptation Strategy Package
In April 2013 the European Commission adopted an EU strategy on adaptation to climate change which has been welcomed by the EU Member States. The strategy aims to make Europe more climate-resilient. By taking a coherent approach and providing for improved coordination, it will enhance the preparedness and capacity of all governance levels to respond to the impacts of climate change.
Methodology for indicator calculation
The satellite-borne sensor from the SMOS (Soil Moisture and Ocean Salinity) mission is used to make global observations of surface soil moisture. Launched in 2009, SMOS looks at microwave radiation emitted from Earth to calculate the amount of moisture held in the surface layer of soil, up to a depth of about 5 cm.
Methodology for gap filling
No methodology references available.
Data sets uncertainty
Quantitative information, from both observations and modelling, on the past trends and impacts of climate change on soil and the various related feedbacks, is very limited. For example, data have been collected in forest soil surveys (e.g. ICP Forests, BioSoil and FutMon projects), but issues with survey quality in different countries makes comparison between countries (and between surveys) difficult . To date, assessments have relied mainly on local case studies that have analysed how soil reacts under changing climate in combination with evolving agricultural and forest practices. Thus, European-wide soil information to help policymakers identify appropriate adaptation measures is absent. There is an urgent need to establish harmonised monitoring networks to provide a better and more quantitative understanding of this system. Currently, EU-wide soil indicators are (partly) based on estimates and modelling studies, most of which have not yet been validated. Nevertheless, in absence of quantification, other evidences can indicate emerging risks. For example, shifting tree lines in mountainous regions as a consequence of climate change may indicate an extinction risk of local soil biota.
Finally, when documenting and modelling changes in soil indicators, it is not always feasible to track long-term changes (signal) given the significant short-term variations (noise) that may occur (e.g. seasonal variations of soil organic carbon due to land management). Therefore, detected changes cannot always be attributed to climate change effects, as climate is only one of the soil-forming factors. Human activity can be more determining, both in measured/modelled past trends (baseline), and if projections including all possible factors were to be made. The latter points towards the critical role of effective land use and management in mitigating and adapting to climate change.
Further information on uncertainties is provided in Section 1.7 of the EEA report on Climate change, impacts, and vulnerability in Europe 2012 (http://www.eea.europa.eu/publications/climate-impacts-and-vulnerability-2012/)
No uncertainty has been specified
Daily Soil Moisture of Europe
provided by Joint Research Centre (JRC)
Soil moisture and ocean salinity
provided by European Space Agency (ESA)
Climate change (Primary topic)
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)
- CLIM 029
Contacts and ownership
EEA Contact InfoGeertrui Veerle Erika Louwagie
EEA Management Plan2012 2.0.1 (note: EEA internal system)
Frequency of updates
For references, please go to www.eea.europa.eu/soer or scan the QR code.
This briefing is part of the EEA's report The European Environment - State and Outlook 2015. The EEA is an official agency of the EU, tasked with providing information on Europe’s environment.
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