Soil moisture (CLIM 029) - Assessment published Nov 2012

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Created : Nov 13, 2012 Published : Nov 20, 2012 Last modified : Nov 20, 2012 04:53 PM

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Sep 08, 2008 - Water retention (CLIM 029) - Assessment published Sep 2008

Generic metadata

Topics:

Climate change (Primary topic)

Tags:

climate change impacts | soil moisture

DPSIR: Impact
Typology: Descriptive indicator (Type A – What is happening to the environment and to humans?)

Indicator codes

CLIM 029

Dynamic

Temporal coverage:

2010

Geographical coverage:

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Contents

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Indicator definition

Global surface soil moisture content based on remote sensing data

Units

m³/m³

Key policy question: How are soil moisture and water retention capacity changing in Europe?

Key messages

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.

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.

Data source:

Soil moisture and ocean salinity provided by European Space Agency (ESA)

Downloads and more info

Key assessment

Past trends

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

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.

Data sources

Soil moisture and ocean salinity
provided by European Space Agency (ESA)
Daily Soil Moisture of Europe
provided by Joint Research Centre (JRC)

Justification for indicator selection

The ability of soil to retain moisture is a significant aspect in the water cycle and is crucial for primary production. The amount of water held in soil is intrinsically linked to our climate and depends largely on texture, structure and the amount of soil organic matter. Variations in any of these variables will affect soil water retention characteristics and ultimately soil functions (e.g. groundwater recharge).

By absorbing many times its weight in water, soil organic matter in mineral soils can contribute to the mitigation of flooding following extreme rainfall events while storing water in the event of more frequent and severe droughts. At low soil carbon contents, an increase in carbon content leads to an increase in water retention in coarse soils and a decrease in fine-textured soils. At high carbon contents, an increase in carbon content results in an increase in water retention for all soil textures.

While water-holding capacity is an intrinsic soil property based on clay content, structure and organic matter levels, water content is highly dynamic and is the balance between rainfall and evapotranspiration. Changes in temperature and precipitation patterns and intensity will affect evapotranspiration, soil moisture and infiltration rates. Conversely, there is also observational evidence that soil moisture deficit exacerbates hot extremes in south-eastern Europe.

Scientific references:

IPCC, 2007. Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, 2007; M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson (eds); Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

Policy context and targets

Context description

In April 2009 the European Commission presented a White Paper on the framework for adaptation policies and measures to reduce the European Union's vulnerability to the impacts of climate change. The White Paper stresses the need to improve the knowledge base and to mainstream adaptation into existing and new EU policies. The European Commission will be publishing an EU Adaptation Strategy in 2013. A number of Member States have already taken action, and several have prepared national adaptation plans.

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.

Targets

No targets have been specified.

Methodology

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

Not applicable

Methodology references

Kerr et al. 2000: The Second of ESA's Opportunity Missions: The Soil Moisture and Ocean Salinity Mission – SMOS Kerr, Y., Font, J., Waldteufel, P., Berger, M., (2000). ESA Earth Observation Quarterly, 66, 18f.

Uncertainties

Methodology uncertainty

Not applicable

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/)

Rationale uncertainty

No uncertainty has been specified

More information about this indicator

See this indicator specification for more details.

Contacts and ownership

EEA Contact Info

Geertrui Veerle Erika Louwagie

Ownership

EEA Management Plan

2012 2.0.1 (note: EEA internal system)

Dates

First draft created: 2012/11/13 08:54:21.874166 GMT+1

Publish date: 2012-11-20T17:53:22+02:00

Last modified: 2012/11/20 16:53:31.140397 GMT+1

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