Socio-economic change could have a much bigger impact than climate change on grazing lands in the world's arid regions. This is the conclusion reached by scientists from the Helmholtz Centre for Environmental Research (UFZ) and the University of Cologne, who simulated ecological and social factors in a computer model. The negative effects of climate change can to a certain extent be offset by an increased herd mobility, write the researchers in a recent issue of the journal Global Environmental Change. However, higher income demands and less available grazing land make it increasingly difficult for nomads to move their herds around to secure their livelihoods.
Arid and semi-arid regions of the world account for around 40 per cent of earth's land surface. The main source of income in these regions is livestock farming, which supports over a billion people. Since rainfall in these regions is low and irregular, many nomadic peoples have adapted their way of life and move their herds to wherever the vegetation offers the best grazing at the time. In doing so they also rest some parts of their grazing land, which is given a chance to recover -- a positive 'side-effect' of mobility. Changing climate conditions, such as bigger rainfall fluctuations, could disrupt this sensitive system. For instance, some parts of north-west Africa are predicted to see a 10 to 20 per cent decrease in rainfall levels. The study therefore aimed to identify climate change limits, within which the livelihoods of households that depend on livestock could be maintained in the long term. The researchers also looked at socio-economic changes, combining a risk assessment with an environmental and economic model.
The evaluation showed that higher fluctuations in annual rainfall sums would have less of an impact on animal farming than a decrease in average levels of annual rainfall. Socio-economic changes, such as higher income requirements, raised the tolerance limits for rainfall fluctuations. "To a certain extent, mobility enables nomads to continue their pastoral farming practices in less productive systems, thereby offsetting negative effects of climate change," reports Dr Romina Martin of the UFZ, who is now conducting research at the Stockholm Resilience Centre. However, higher income requirements and less access to grazing land make it increasingly difficult to maintain this mobility.
"Although our model focuses on nomadic grazing systems and only considers the most important drivers, it reflects the consequences of the dramatic change in land use patterns in arid regions," says Prof. Karin Frank of the UFZ. "However, our approach is not restricted to studying grazing systems. It can be used anywhere where the dynamics of ecosystem services are closely linked to people's livelihoods."
"Our results emphasize the fact that the form of pastoralism practised by nomadic herdsmen enables sustainable use of sensitive ecosystems and that the ecosystems are resilient enough, when used in this way, to adapt to changes in rainfall and therefore to climate change," says Dr Anja Linstädter of the University of Cologne. Dr Birgit Müller of the UFZ adds: "So we should not simply dismiss nomadism as an outdated tradition." In many arid regions this could be the only sustainable form of land use -- unlike intensive crop farming, which enables higher yields in those regions, but over-uses the soil and water resources to such an extent that agriculture soon stops being viable. In the authors' view, this also casts a different light on the discussion about what, to western eyes, appears to be unused land in many parts of Africa. In reality, this communal grazing land represents an important basis for subsistence for local populations.
The study incorporated research findings from field studies conducted in Morocco's Atlas Mountains and Oriental region, and in the highlands of Tibet, as part of two interdisciplinary projects. Under the umbrella of the IMPETUS project at the Universities of Cologne and Bonn, Germany, climatologists, hydrologists, geographers, rangeland ecologists and ethnologists spent 12 years investigating the consequences of climate and land use change on natural resources in the High Atlas Mountains in Morocco. Their data on rainfall fluctuations and on the productivity and regenerative capacity of pasture vegetation formed the basis for the ecological part of the model. By contrast, the Collaborative Research Centre for Difference and Integration at the German Research Foundation (DFG) focused on investigating the lives of nomadic peoples in the "Old World dry belt." Archaeologists, ethnologists, geographers, historians and orientalists at the Universities of Halle and Leipzig, Germany, collaborated with colleagues from other institutes on this project for more than ten years because nomadic and settled cultures have existed side-by-side between Morocco and Tibet for over 5000 years.
Some unconventional methods have since been used to disseminate the findings: within the DFG's Collaborative Research Centre for Difference and Integration, UFZ scientists worked with the Berlin University of the Arts (UdK) to develop a strategic game to explain the connections between land use, rainfall and livestock capital to a broad public. In the game, up to six players take on the role of a nomadic herdsman. The aim is to increase the herdsman's capital in the form of sheep. Players have to take decisions that depend not only on the state of the grazing land, but also on the day-to-day challenges of life in the steppes. The NomadSed board game is suitable for ages ten and over and is now also being used for development education, e.g. by the "Vétérinaires Sans Frontières Germany" in Kenya.
The study was funded by the German Research Foundation (DFG, project SFB 586 ''Difference and Integration''), the German Ministry of Education and Research (BMBF, project IMPETUS) and the Helmholtz Association.
- Romina Martin, Birgit Müller, Anja Linstädter, Karin Frank. How much climate change can pastoral livelihoods tolerate? Modelling rangeland use and evaluating risk. Global Environmental Change, 2014; 24: 183 DOI: 10.1016/j.gloenvcha.2013.09.009
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