Willem Ligtvoet

On the relation between weather-related disaster impacts, vulnerability and climate change

Disasters such as floods, storms, heatwaves and droughts can have enormous implications for health, the environment and economic development. In this article, we address the question of how climate change might have influenced the impact of weather-related disasters. This relation is not straightforward, since disaster burden is not influenced by weather and climate events alone—other drivers are growth in population and wealth, and changes in vulnerability. We normalized disaster impacts, analyzed trends in the data and compared them with trends in extreme weather and climate events and vulnerability, following a 3 by 4 by 3 set-up, with three disaster burden categories, four regions and three extreme weather event categories. The trends in normalized disaster impacts show large differences between regions and weather event categories. Despite these variations, our overall conclusion is that the increasing exposure of people and economic assets is the major cause of increasing trends in disaster impacts. This holds for long-term trends in economic losses as well as the number of people affected. We also found similar, though more qualitative, results for the number of people killed; in all three cases, the role played by climate change cannot be excluded. Furthermore, we found that trends in historic vulnerability tend to be stable over time, despite adaptation measures taken by countries. Based on these findings, we derived disaster impact projections for the coming decades. We argue that projections beyond 2030 are too uncertain, not only due to unknown changes in vulnerability, but also due to increasing non-stationarities in normalization relations.

Is Western consumption of Nile perch from Lake Victoria sustainable

The exploitation of Nile perch resources of Lake Victoria has strongly increased during recent years. This is apparent from decreasing catch rates and ever increasing numbers of fishermen, fishing craft and gears. Despite this, it remains economic to continue the exploitation and exportation of Nile perch products. Exports to the EU, however, seemed to have reached their maximum in 2003, which could have been due to competition from cheaper fish products from certain Asian countries, as well as to market diversification by the East African exporting firms. Fish prices paid to fishermen increased over time as a result of the success of the Nile perch fishery. However, the increased influx of money into the fishing communities did not necessarily lead to a reduction in poverty. This could be due to the lack of saving and investment possibilities. In the absence of sufficient schooling, youths automatically enter the fishery sector and as a result of relatively low investment costs and high earnings the fishing effort will continue to increase until the open-access based management regime is replaced by a licensing system. The role that Beach Management Units can play in managing the human and fisheries resources will have to be strengthened. It is concluded that the economic gains based on the new fishery, in itself proved to be insufficient to provide a structural sustainable development, due to the restricted social and institutional capacity which hampers the riparian populations ability to adapt to the new social and fishery challenges.