Weather and resource information as tools for dealing with farmer–pastoralist conflicts in the Sahel

Conflicts between pastoralists and farmers in the Sahel mainly arise from competition over land and water resources or because of livestock damage to crops. Rather than being linked to larger environmental change processes such as climate change, conflicts are often caused by inappropriate zoning of land, governance and unequal power relations between stakeholders. However, conflicts may be affected by more short-term weather and resource information that guide mobility of pastoralists. In this paper, we therefore explore if improved weather and resource information and improvement in its communication could prevent conflicts or reduce their severity. Based on a survey of key stakeholders involved in dissemination of weather and resource information and studies on pastoral access to and use of information, we conclude that improved information may both reduce and increase the level of conflict, depending on the context. Communication of information will need to go beyond just the weather and resource information and also include the multiple options for herd movements as well as providing information on herd crowding and potential conflict areas

Klimaændring, ørkendannelse og konflikt i Sahel

Kjeld Rasmussen og Ole Wæver skriver om klima som sikkerhedsproblem.&nbsp

Simulation of Plasticity of Copper(II) Coordination Polyhedron: Empirical Force Field Model with Distorsion Coordinate Potential

In order to reproduce the geometry of tetracoordinated copper (II) chelates with a »distorted« coordination polyhedron (planar/ /tetrahedral), two new empirical functions for the calculation of the conformational potential were introduced. The first depends on the distorsion coordinate (1, defined as an angle between bisectors of two valence angles around the central atom. The second function is a two-well valence angle bend ing potential for valence angles around copper, with minima at 90" and 109.47°. The new functions were tested on bis-(N,N-dimethylvalinato)- copper(II). A consistent force field (CFF) calculation with the new functions yielded the correct geometry of copper coordination, i. e. a distorted tetrahedron. The valence angles around copper (N- -Cu-N, O-Cu-N and O-Cu-O) were reproduced fairly well with root-mean square deviation with respect to the crystal structure of 3.20° and 3.73° for the model with a two-well and the model with a quadratic valence angle bending potential, respectively. The measured diastereoselectivity (Gibbs energy difference between CU(L-ligand12 and Cu=ligand) (o-ligand)) was reproduced within 3 kJ mol-1

Human population growth offsets climate-driven increase in woody vegetation in sub-Saharan Africa

The rapidly growing human population in sub-Saharan Africa generates increasing demand for agricultural land and forest products which presumably leads to deforestation. Conversely, a greening of African drylands has been reported, but this has been difficult to associate with changes in woody vegetation. There is thus an incomplete understanding of how woody vegetation responds to socio-economic and environmental change. Here we used a passive microwave Earth Observation data set to document two different trends in woody cover land area for 1992-2011: an 36% increase (6,870,000 km²), largely in drylands, and an 11% decrease (2,150,000 km²), mostly in humid zones. Increases in woody cover were associated with low population growth and driven by increases in CO2 in the humid zones and by increases in precipitation in drylands, whereas decreases in woody cover were associated with high population growth. The spatially distinct pattern of these opposing trends reflects (1) the natural response of vegetation to precipitation and atmospheric CO2 and (2) deforestation in humid areas, minor in size but important for ecosystem services, such as biodiversity and carbon stocks. This nuanced picture of changes in woody cover challenges widely held views of a general and ongoing reduction of the woody vegetation in Africa