Effects of Climate Change

It is very difficult to exactly tell the effects of climate change since many uncertainties and variation in variables such as precipitation, evaporation, storms, sea levels etc.

The available studies indicate that the impact would be more severe for Asian and African countries than those situated at higher Iatimdes. In terms of GDP, these impacts would be of the order of 8.5% for South Asian and African countries whereas for OECD countries, the order would be 1.6%. The effect on the world as a whole would be of the order of 1.5 to 2%.

12.6.1 Climate Change in Asia

Climate change is a matter of special concern for Asian countries because they frequently face the problems of floods, droughts, cyclones and typhoons. These phenomena greatly affect the economy and human settlements in these countries.

Table 12.1 gives some statistical data for the Asian region.

Table 12.1 Some Basic Statistical Data

The region extends from 80^o longitude (70^oE to 150^oE) to 40^o latitude (from 30^o N to 10^o S).

2.4 billion by the year 2025.

The climate is dominated by the summer southwest monsoon and the winter northeast monsoon. They affect the precipitation which in turn is linked to water availability for agricultural and domestic use. The tropical cyclones in the northern Indian Ocean and north-western Pacific Ocean also affect the regional weather. The El Nino Southern Oscillation (ENSO) phenomenon also has influence on climate and sea level.

A special report of the IPCC Working Group II (The Regional Impacts of Climate Change: An Assessment of Vulnerability) has described the impacts under the following categories.

(a) Impacts on Temperature and Rainfall

It is predicted that the warming would be faced through out the region but its extent would be lower than the average global warming. The proximity to sea would cause regional variations. Thus, the warming would be least in the islands and coastal areas of Indonesia, Philippines, coastal South Asia and Indo­China while it would be greatest in the continental areas of South Asia and Indo-china except from June to August in South Asia where reduced warming could occur.

The rainfall would be maximum over South Asia and the Indo-China peninsula in April-September but would be minimum over Indonesia and near Australia.

(b) Impacts on Ecological Systems

It has been expected that the ecosystems in the mountains and planes in Asia would shift upwards. At high elevations, weedy species would displace trees. There will be increased soil erosion in Greater Himalayas and hence, the rate of vegetation change would be slow. There will be complex changes in distribution Ofhealthy rainforest and drier monsoon forest. It is expected that in Thailand, the tropical forest area would increase from 45% to 80% of the total forest cover whereas in Sri Lanka, the tropical rainforest would decrease by 2­11% and tropical dry forest would increase by 7-8%.

Coastal ecosystems such as coral reefs could be bleached by increase in sea water temperature. Similar phenomenon was observed during the ENSO event in 1983 when coral reefs in Indonesia faced severe bleaching.

The other coastal ecosystem, which would be affected by sea level rise and increase in temperature, are mangroves. About 40% of the total mangrove area i.e. about 75,000 km² lies in tropical Asia. Out of this 40%, 23% is in Indonesia. Bangladesh has the largest continuous mangrove area in the world. The Sunderban region is already facing a threat to many mammals, birds, reptiles and amphibian species due to sea level rise. This area would also be vulnerable to cyclonic storms and surges.

(c) Impacts on Agriculture

Many cereal and tree crops of the region have been studied with respect to changes in temperature, moisture and CO₂ concentration. It is expected that the yields of rice, wheat and sorghum would increase with the increase in CO₂ concentration but there would be region wise variation in growing seasons, crop management, storage and distribution. The agricultural areas of tropical Asia are vulnerable to frequent floods, droughts, cyclones and storms which damage life, property and affect agricultural output. These factors were responsible for loss of about half a million tonnes of rice in Bangladesh during 1962-88 which amounted to about 30% of its average annual food grain exports.

(d) Impacts on Coastal Zones

In coastal areas, rise in sea level and increase in rainfall would lead to the following effects:

• Land loss and population displacement

• Increased flooding of low lying coastal areas

• Loss of agricultural yield and employment

• Decrease in coastal tourism by erosion of sandy beaches

The large delta regions OfBangladesh, Myanmar, Vietnam and Thailand, and low-lying areas of Indonesia, the Philippines and Malaysia are vulnerable to coastal erosion, land loss, sea flooding, inundation etc. The Ganges- Brahmaputra delta is one of the world’s most densely populated areas and would face serious drainage and sedimentation problems due to sea level rise besides coastal erosion and land loss.

The economy and food security of the region heavily depends upon aquaculture and marine fisheries. Fisheries account for about 4% of the GNP in the Philippines and it employs about a million people. Fish populations are strongly affected by even slight changes in temperature, salinity, wind speed and direction, ocean currents etc. A rise in sea level would cause saline water to penetrate further inland which would increase the habitat of brackish-water fisheries.

According to the studies, alm rise of sea level would lead to land loss in Bangladesh, Indonesia, India and Malaysia. Table 12.2 shows the extent of damage.

Table 12.2 Effects of Sea Level Rise

(e) Impact on Hydrology and Water Resources

The Himalayas are very critical for the availability of water to continental monsoon in Asia. The increase in temperature and variation in precipitation would accelerate recession of glaciers and increase the danger from floods. There would also be an increase in the peak flows in the rivers and increased sediments in turn would have major effects on hydropower generation, agriculture and urban water supply. The water would increase in snow fed rivers for short term but in the long run, there would be a stress on water resources due to lesser availability and increasing demand.

(f) Impacts on Human Health

The occurrence and extent of vector- bome diseases would increase. The climate change would increase the spread of malaria, dengue and schistosomiasis which are reasons of mortality and morbidity in Tropical Asia.

Similarly, water-borne and water related infectious diseases would also show an increase with the higher temperature and higher humidity conditions and a lower water quality due to water crisis.

12.6.2 Impacts of Climate Change on India

India is highly vulnerable to climate change. Our economy heavily depends upon climate sensitive sectors such as agriculture and forestry. India is already facing problems of increasing population, rapid urbanisation, industrialization and economic development. The climate change would further increase these pressures.

It is expected that doubling of CO₂ concentrations would increase the temperature by 2.33^oC to 4.78^oC. The frequency of heavy rainfalls would increase in South and Southeast Asia. The annual mean maximum and minimum surface air temperatures would increase by 0.7^oC and l^oC by 2040s as compared to 1980s. This increase would be higher for adjoining oceans. The specific impacts are as follows:

(a) Impact on Agriculture

Agriculture and related activities constitute the single largest component of Indian economy. It contributed 27% of GDP in 1999-2000. The agricultural export amounted to 13-18% of the total exports (Ministry of Finance, 2002).

A decrease in rice yield by 3-15 % has been reported by a rise in temperature by 1.5⁰C and a 2 mm increase in precipitation. Another study has reported a

variation of -22 to 18% under different climatic conditions for soybean fields considering +2 to +4^oC rise in temperature and + 20 to + 40% change in precipitation.

Many researches and studies are undergoing to assess the impacts of various agencies at different levels.

(b) Impacts on Forestry

Forests contribute 1.7% to the GDP of India (MoEF sources) Non- timber forest products yield 40% of total forest revenues and contribute 55% of forest­based employment.

The geographical distribution, composition and productivity is largely determined by the climate. Thus, forest ecosystems would be greatly affected by the climate change.

The increased temperature and rainfall could result in increased productivity, migration of forest types to higher elevations and conversion of drier forests to moister types.

Another study showed that teak productivity would decline due to decrease in the soil moisture content. It also indicated the decrease in the productivity of moist deciduous forests from 1.8 m³ / ha to 1.5 m³/ ha.

(c) Impacts on Coastal Zones

India has a low-lying densely populated coastline which extends to about 5700 km. It is vulnerable to rise in sea level. A Im rise in sea level would inundate 1700 km² of prime agricultural land. Another study estimated that a total of 5763 km² area and 7.1 million people would be affected if no protection measures are taken. The economic loses would be very-very high. Also coastal infrastructure, oil explorations and tourist activities would be at risk.

The frequency and intensity of storms and cyclones would increase. The typical cycl6ne of 1999 in Orissa took a toll of about 10,000 people.

(d) Impacts on Water Resources

India has large amount of total water resources and rainfall but they are not evenly distributed. Thus, there is an imbalance in the demand and supply of the quantity and the quality of water.

Climate change would further aggravate the water crisis. The lower rainfall.. and increased evaporation would lead to less run off, affecting the availability of freshwater. The soil moisture and aridity level would also be affected.

Studies show that melting of snow in the high Himalayas would cause floods in catchments. The impact would be more on the western side. There would be an increased risk of floods in North India during wet season due to rise in snowline because of increased temperature.

12.7