Climate Change 2001:
Working Group II: Impacts, Adaptation and Vulnerability
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Table 4-10: Effect of climate change on navigation opportunities on River Rhine (Grabs, 1997).
Average Annual Number of Days
when Large Boat-Trains can Move
(flows between 2000 and 5500 m3 sec-1 )

Kaczmarek et al. (1996) assessed the impact of climate change on the water supply system in the Warta River basin in Poland, looking at two climate change scenarios in the context of increasing demand for water (particularly from irrigation). In the absence of climate change, they show that there would be supply problems in part of the system by 2050, simply because of the increase in demand. Under one of the scenarios, inflows to supply reservoirs would increase sufficiently to prevent supply problems; under the other scenario, the risk of shortage would increase substantially (the probability of an annual deficit of 10% would increase from 4 to ~25%, for example). Kaczmarek et al. (1996) also looked at the feasibility of one adaptation option—transferring water from one reservoir to another—and showed how it could lessen the likelihood of shortage.

The River Rhine is a very important transport route within Europe. Grabs (1997) considered the effect of two climate change scenarios on navigation opportunities, having translated climate into streamflow by using a catchment water balance model. Table 4-10 summarizes the results: Under one of the scenarios, there would be little obvious effect on navigation opportunities, but under the other movement could be curtailed, particularly by the middle of the 21st century.

The vast majority of the impact assessments in Table 4-8 describe the effects of climate change on the reliability of an existing system. Very few explore the costs of these impacts, primarily because of difficulties in deciding the basis for calculation. Are the costs of climate change equal to the cost of continuing to provide the current standard of service? Are the costs of services foregone (in terms of extra flood damages or reduced use of water), or are they incurred in providing services at a new economically-optimum level? In other words, estimates of the cost of climate change must consider explicitly the measures used to adapt to that change, and the economic costs of climate change will depend on the adaptation strategies adopted. Carmichael et al. (1996) present one of the few studies that has tried to cost the implications of climate change. They investigated the treatment costs necessary to maintain a given water quality standard (expressed in terms of dissolved oxygen content) in a river in Slovakia and calculated the least costly treatment under the present hydrological regime and under one scenario for the 2020s. They showed that costs would be little different if the aim were to meet a 4 ppm dissolved oxygen target under average summer conditions but would rise by a factor of about 14 (at current prices) if the aim were to meet the same target under low-flow conditions, even taking a least-cost approach.

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