Background, aim and scope

Life cycle assessment (LCA) enables the objective assessment of global environmental burdens associated with the life cycle of a product or a production system. One of the main weaknesses of LCA is that, as yet, there is no scientific agreement on the assessment methods for land-use related impacts, which results in either the exclusion or the lack of assessment of local environmental impacts related to land use. The inclusion of the desertification impact in LCA studies of any human activity can be important in high-desertification risk regions.
Main features

This paper focuses on the development of a methodology for including the desertification environmental impact derived from land use in LCA studies. A set of variables to be measured in the life cycle inventory (LCI), their characterisation factors (CFs) and an impact assessment method for the life cycle impact assessment (LCIA) phase are suggested. The CFs were acquired using a geographical information system (GIS).
Results

For the LCI stage it is necessary to register information on: (1) the four biophysical variables of aridity, erosion, aquifer overexploitation and fire risk, with a created scale of values; (2) the geographical location of the activity and (3) the spatial and temporal extension of the activity. For the CFs, the four LCI biophysical variables in (1) were measured for the main terrestrial natural regions (ecoregions) by means of GIS.
Discussion

Using GIS, calculation of the CF for the aridity variable shows that 38% of the world area, in eight out of 15 existing ecoregions, is at risk of desertification. The most affected is the tropical/subtropical desert. The LCIA model has been developed to identify scenarios without desertification impact.
Conclusions

The developed method makes possible the inclusion of the desertification impact derived from land use in LCA studies, using data generally available to LCA users.
Recommendations and perspectives

While this LCIA model may be a simplified approach, it can be calibrated and improved for different case studies. The model proposed is suitable for assessing the desertification impact of any type of human activity and may be complemented with specific activity indicators, and although we have considered biophysical factors, the method can be extended to socio-economic vectors.
Researchers have measured the degradation of the planet's soil using the Life Cycle Assessment (LCA), a scientific methodology that analyses the environmental impact of human activities, and which now for the first time includes indicators on desertification. The results show that 38 percent of the world is made up of arid regions at risk of desertification.

"Despite improvements in the LCA, it has a methodological weakness, which is a lack of environmental impact categories to measure the effect of human activities such as cultivation or grazing on the soil," Montserrat Núñez, lead author and a researcher at the Institute of Agro Food Research and Technology (IRTA), said.

The research, published in the latest issue of the International Journal of Life Cycle Assessment, is the first study in the world to include the impact of desertification in the LCA, based on classifying 15 natural areas or "eco-regions" according to their degree of aridity. By simultaneously using the LCA and a Geographic Information System (GIS), the researchers have shown that eight of these 15 areas can be classified as at risk of desertification, representing 38% of the land surface of the world.

The eight natural areas at risk are coastal areas, the Prairies, the Mediterranean region, the savannah, the temperate Steppes, the temperate deserts, tropical and subtropical Steppes, and the tropical and subtropical deserts.

"The greatest risk of desertification (7.6 out of 10 on a scale produced using various desertification indicators) is in the subtropical desert regions -- North Africa, the countries of the Middle East, Australia, South West China and the western edge of South America," the scientist explains.

These are followed by areas such as the Mediterranean and the tropical and subtropical Steppes, both of which score 6.3 out of 10 on the scale of desertification risk. Coastal areas and the Prairies are at a lower risk of desertification, with 4 out of 10.

"Unsustainable land use may lead to soil becoming degraded. If this happens in arid, semi-arid and dry sub-humid regions, such as Spain, this degradation is known as desertification, and the effects can be irreversible, because they lead to areas becoming totally unproductive," says Núñez, who worked on the study with scientists from the Autonomous University of Barcelona and the National Technological University in Mendoza, Argentina.

In order to establish their methodology, the researchers used four biophysical variables that are the main causes of desertification -- aridity, erosion, over-exploitation of aquifers and risk of fire. "This makes it possible to satisfactorily evaluate the impact of desertification of a particular human activity, and compare the impact of the same activity in a different place, or the impact of different activities carried out in the same place," explains the researcher. The methodology proposed by the scientists is currently being put to use in various case studies in Spain and Argentina.

Completing the study of desertification

The new research shows that using the LCA in combination with GIS makes it easier to adapt the LCA to study the impacts of land use, not only in the case of desertification, but also in terms of loss of biodiversity, erosion, or even water consumption.

This new methodology will provide the Life Cycle Assessment (LCA) with an environmental impact category that will make it possible to measure "the desertification potential caused by any human activity," adds Núñez.

The Life Cycle Assessment (LCA) is a scientific methodology that objectively analyses the environmental impacts of an activity or process, taking in the full cycle, from extraction of raw materials right through to management of the waste generated at the end of this material's useful life.