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* Area below the 1 in 1,000 year flood level.

* Area below the 1 in 1,000 year flood level.

Table 6.6 shows estimates of coastal flooding due to storm surge, taking into account one adaptation assumption. Asia and Africa experience the largest impacts: without sea-level rise, coastal flooding is projected to diminish as a problem under the SRES scenarios while, with sea-level rise, the coastal flood problem is growing by the 2080s, most especially under the A2 scenario. Increased storm intensity would exacerbate these impacts, as would larger rises in sea level, including due to human-induced subsidence (Nicholls, 2004). Figure 6.8 shows the numbers of people flooded in the 2080s as a function of sea-level rise, and variable assumptions on adaptation. Flood impacts vary with sea-level rise scenario, socio-economic situation and adaptation assumptions. Assuming that there will be no defence upgrade has a dramatic impact on the result, with more than 100 million people flooded per year above a 40 cm rise for all SRES scenarios. Upgraded defences reduce the impacts substantially: the greater the upgrade the lower the impacts. This stresses the importance of understanding the effectiveness and timing of adaptation (Section 6.6).

Sea level rise (m)

Figure 6.8. Estimates of people flooded in coastal areas due to sea-level rise, SRES socio-economic scenario and protection response in the 2080s (following Nicholls and Lowe, 2006; Nicholls and Tol, 2006)

Sea level rise (m)

Figure 6.8. Estimates of people flooded in coastal areas due to sea-level rise, SRES socio-economic scenario and protection response in the 2080s (following Nicholls and Lowe, 2006; Nicholls and Tol, 2006)

6.4.2.4 Human health

Coastal communities, particularly in low income countries, are vulnerable to a range of health effects due to climate variability and long-term climate change, particularly extreme weather and climate events (such as cyclones, floods and droughts) as summarised in Table 6.7.

The potential impacts of climate change on populations in coastal regions will be determined by the future health status of the population, its capacity to cope with climate hazards and control infectious diseases, and other public health measures. Coastal communities that rely on marine resources for food, in terms of both supply and maintaining food quality (food safety), are vulnerable to climate-related impacts, in both health and economic terms. Marine ecological processes linked to temperature changes also play a role in determining human health risks, such as from cholera, and other enteric pathogens (Vibrio parahaemolyticus), HABs, and shellfish and reef fish

Table 6.6. Estimates of the average annual number of coastal flood victims (in millions) due to sea-level rise (following Nicholls, 2004). Assumes no change in storm intensity and evolving protection**. Range reflects population growth as reported in Table 6.1. Base= baseline without sea-level rise; aSLR = additional impacts due to sea-level rise.

Region Case Timelines, SRES socio-economic (and sea-level rise scenarios in metres)

2020s 2050s 2080s

A1FI A2 B1 B2 A1FI A2 B1 B2 A1FI A2 B1 B2

(0.05) (0.05) (0.05) (0.06) (0.16) (0.14) (0.13) (0.14) (0.34) (0.28) (0.22) (0.25)

2020s 2050s 2080s

A1FI A2 B1 B2 A1FI A2 B1 B2 A1FI A2 B1 B2

(0.05) (0.05) (0.05) (0.06) (0.16) (0.14) (0.13) (0.14) (0.34) (0.28) (0.22) (0.25)

Australia

Base

0 0

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