Climate change impacts in Asian countries

Flooding, one of the main natural disasters in China, occurs frequently, not only in southern China where a humid monsoon climate prevails but also in arid and semiarid northern China. Changes in risk of flooding are considered to be one of the potential impacts of climate change, since some studies indicate an increase in frequency/intensity of heavy rain. On the other hand, the additional investment in infrastructure for preventing flood disasters in the early decades of this century have the potential to mitigate not only the additional flood disasters caused by future climate change but also those which currently occur because of climate variability.

We evaluated the optimal amount of investment in infrastructure for preventing flood disasters by estimating flood damage to cultivated land under four alternative scenarios;

(i) policy makers do not arrange adaptation investment for projected damage, and climate change does not occur (baseline),

(ii) policy makers do not arrange adaptation investment for projected damage, but climate change does occur,

(iii) policy makers arrange adaptation investment for projected damage, but climate change does not occur, and

(iv) policy makers arrange adaptation investment for projected flood damage, and climate change does occur.

The simulated results indicate that flooding will damage 1.13% of cultivated land in 2100 even if investment takes climate change into consideration and climate changes do occur (scenario iv). The damage will gradually increase to 3.11% by the end of the century when there is no investment in flood prevention infrastructure to combat projected climate change but climate change does occur (scenario ii). The consumer's utility per capita will decrease by 0.83% (compared with the baseline case; scenario i), when no adaptation investment is implemented, but climate change occurs (scenario ii). The decrease of utility can be reduced to 0.1% if adaptation investment is implemented (scenario iv). Even if investment is larger than the optimal level, consumer's utility per capita will not be completely lost. According to this analysis, it appears to be a good strategy to invest in flood prevention infrastructure even if the occurrence and magnitude of climate change is still uncertain.

Under the unsustainable scenario, which reflects a high rate of population growth and low rate of improvement in water-use efficiency, the water stress index (ratio of water withdrawal to renewable water resource in each basin) will significantly increase in India, leading to increased drought risk. On the other hand, under the sustainable scenario, water stress index will decrease slightly in most basins reflecting a high rate of improvement in water use efficiency. (There are a small number of exceptional basins where water stress index increases because of the regional pattern of climate change.)

Whether current forest vegetation will be damaged or not is identified by comparing potential velocity of forest moving with the velocity of vegetation zone shift that is estimated by considering climate change scenarios. The velocity of forest moving is estimated to be in the range of 0.25-2.0 km year-1 in our assessment. In the SRES A2 scenario, where the temperature increase is higher than that in the other SRES scenarios, the extinction area of the Korean Peninsula would be 2.08% if the velocity of forest moving is assumed to be 0.25 km year-1.

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