Posted March 1998
Potential impacts of sea-level rise
on populations and agriculture
by R. Gommes, J. du Guerny, F. Nachtergaele and R. Brinkman
Food and Agriculture Organization of the United Nations
Cover page | 1. Introduction / setting | 2. Effects of SLR | 3. Lessons from the past | 4. Vulnerability index | 5. Conclusions, references | 6. Appendix table: AOSIS countries
SEVERAL FACTS emerge from the literature, analyses and the data presented in the present paper. First, accelerated sea-level rise seems to be one of the more "certain" consequences of global climate change with a "worst scenario" increase of 95 cm by 2100, while the population of the world will stabilize around 2050 with urbanization continuing to increase. Current population densities are generally highest - and the GDP lowest - in the more insular countries of the world.
Large relative local differences will be observed in sea-level rise, resulting in large local differences in impacts. In general, it is likely that the relative importance of coastal disasters will decrease, even if their number and the associated economic losses are likely to increase due to general economic development.
Direct effects on the most vulnerable coastal areas, for instance deltas, are difficult to assess, in particular because the dynamic of deltas is determined by climatic conditions in the whole catchment basin and because coastal climates do not follow general patterns. Potentially, coastal and delta agriculture and populations will adapt to changing conditions, but impact of local disasters could increase. In general, the relative cost of protection (as a percentage of GNP) will be much higher in small island states than in other coastal areas, where the capacity to invest in protective measures is limited.
Current trends indicate a possibility that "medium" vulnerability will increase, but extremes could decrease in relative frequency at a global scale, based on current observations and population trends. In particular, the trend towards greater urbanization constitutes a positive factor in the present context, as cities provide a rather safe environment. Many variables examined display a positive skew: where the extremes of one or more of the variables are at play at the same time, risks will be very high.
It is clear that, given the gradual nature of the foreseen changes, populations and agriculture will gradually adapt and move. The cost of protection is found to be relatively high in many small islands (5% of GNP, and above); protective measures may be possible only where their cost remains low compared with GNP growth.
Policy measures will have to include construction standards and other non-structural preventive measures (emergency plans, insurance) in addition to protection. Some countries should take action now to ensure that their agricultural production is not concentrated in areas which are likely to become more vulnerable under sea-level rise conditions.
It is clear that efforts should be made to identify possible run-away situations, and they should be kept under constant observations.
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To: Cover page | 1. Introduction / setting | 2. Effects of SLR | 3. Lessons from the past | 4. Vulnerability index | 5. Conclusions, references | 6. Appendix table: AOSIS countries
© FAO 1998