सेप्टेम्बर 23, 2014
The leaked report of the world’s leading body of climate experts says threats to water, food, health, industries and ecosystems in Asia are all rising due to global warming
Asia faces a worsening water crisis, according to a leaked report from theIntergovernmental Panel on Climate Change (IPCC).
Water demand from rising populations and living standards, and poor management, – in addition to climate change – will increase the scarcity of freshwater for large portions of Asia, says the summary of the IPCC Working Group II report, due to be published on March 31.
Working Group II deals with adaptation and vulnerability to climate change. The report of Working Group I – which looks at climate science – was released late last year. The report of Working Group III – on mitigating climate change – is scheduled for release in April. Together they form the fifth assessment report of IPCC, a collective of thousands of scientists who form the leading international body for the assessment of climate change. The fourth assessment report was released in 2007.
Talking about the effects of climate change on water availability, the scientists say declines in rainfall and river runoff will undoubtedly affect millions of people and may lead to increased tension due to water scarcity in some parts of Asia, especially arid areas. Droughts will probably compound the mismanagement of water resources and add to existing tensions, they add.
The IPCC says climate change may further complicate the unsustainable consumption of groundwater for irrigation and other uses in some locations, such as the Indian states of Rajasthan, Punjab, and Haryana. Climate change will challenge water supply issues in South Asia and may adversely affect agricultural and livestock sustainability.
Agriculture and Food Security
Due to the impacts of climate change, many regions are expected to see a decline in food productivity, with the largest numbers of food-insecure people in South Asia. Higher temperatures are expected to decrease rice yields as a result of shorter growing periods.
Sea level rise also threatens many Asian coastal areas and is projected to inundate low lying areas which would negatively affect rice growing regions. Fisheries, a major source of livelihoods and protein for many countries, are also projected to be negatively impacted by climate change, especially in South and Southeast Asia.
The Indo-Gangetic Plains of India, which produce about 14-15% of the global wheat crop, could suffer significant reductions due to climate change-induced heat stress, affecting about 200 million people. Warming temperatures may adversely affect rice and other crops growing near their heat stress limits in places such as Pakistan and northern India (during October), southern India (April-August), eastern India and Bangladesh (March-June), and China (July-August).
The most vulnerable regions for reduced rice yield is projected for western Japan, eastern China, the southern part of the Indochina peninsula, and the northern part of South Asia.
Sea-level rise threatens coastal and deltaic rice production areas in Asia, such as those in Bangladesh, Myanmar, and the Mekong River Delta. About 7% of Vietnam’s agricultural land may be submerged due to sea-level rise.
Climate change will compound existing threats to fisheries, including overfishing, pollution, dam construction, etc. Rising temperatures, reduced precipitation, and increased droughts will decrease river flow in some parts of Asia, which in turn would adversely affect fish reproduction. Additionally, increased precipitation and floods will scour rivers and also adversely affect fish reproduction.
Coldwater fish will be threatened as rising water temperatures make much of their current habitat unsuitable. Habitats that depend on seasonal inundation, including floodplain grasslands and freshwater swamp forests would be adversely affected by reduced precipitation and droughts.
Reduced dry season flows together with sea-level rise will increase saltwater intrusion into many Asian deltas, compound existing threats, and negatively impact both capture fisheries and aquaculture production.
Warming ocean temperatures, ocean acidification, and the loss of coral reefs would greatly decrease the abundance of marine fisheries, negatively affecting many countries in South and Southeast Asia.
Effects on homes and factories
By the middle of this century, Asia’s urban population will increase by 1.4 billion and will account for over 50% of the global population. Climate change will compound the many stresses caused by rapid urbanization, industrialization, and economic development. Asia experienced the highest number of weather- and climate-related disasters in the world during 2000-08 and suffered huge economic losses, accounting for the second highest proportion (27.5%) of the total global economic loss.
A large proportion of Asia’s population lives in low elevation coastal zones that are particularly at risk from climate change hazards, including sea-level rise, storm surges, and typhoons. Half to two-thirds of Asia’s cities with a million or more inhabitants are exposed to one or multiple hazards, with floods and cyclones being the most important.
Climate change will also impact industry both directly by affecting industrial production and indirectly by affecting the cost of infrastructure and potential damages.
Three of the world’s five most populated cities – Tokyo, Delhi, and Shanghai – are located in areas with high risk of floods and climate change threatens to increase their frequency and intensity. By the 2070s, the top Asian cities in terms of population exposure to coastal flooding are expected to be Kolkata, Mumbai, Dhaka, Guangzhou, Ho Chi Minh City, Shanghai, Bangkok, Rangoon, and Hai Phòng. The top Asian cities in terms of assets exposed are expected to be Guangdong, Kolkata, Shanghai, Mumbai, Tianjin, Tokyo, Hong Kong, and Bangkok.
Climate change-induced floods threaten vulnerable regions that have high concentrations of people and infrastructure in India, Bangladesh, and China.
The combined effect of climate change and over-withdrawal of groundwater in many Asian cities, such as Bangkok, Manila and Tianjin will likely result in land subsidence and may increase hazard exposure due to coastal inundation and sea-level rise.
Climate change threatens to disrupt basic services such as water supply, sanitation, energy provision, and transportation systems, which has serious implications for local economies and in some cases could lead to mass migration.
Effects on health
More frequent and intense heat-waves in Asia will increase mortality and morbidity in vulnerable groups. Increases in heavy rain and temperature will increase the risk of diarrheal diseases, dengue fever, and malaria.
The scientists say climate change impacts such as increased flooding and extreme weather events will likely lead to deteriorated drinking water quality, mosquito proliferation, increased exposure to rodent-borne pathogens and intermediate snail hosts of Schistosoma, and increased disease epidemics.
Flooding-induced contamination of urban water supplies will probably increase exposure to pathogens and toxic compounds. The report says extreme flooding may also increase mental disorders and posttraumatic stress syndrome, which have been previously observed in disaster-prone areas in India.
Warmer temperatures and more heat waves will likely to lead increased mortality and morbidity especially in vulnerable populations, such as the elderly, children, the poor and people with cardiovascular and respiratory disorders. This has already been documented in populations in India, Thailand, and several cities in East Asia. Climate change will probably increase the frequency of heat stress disorders among workers, leading to productivity losses.
Climate change will affect the local transmission of many climate-sensitive diseases. Increases in heavy rain and temperature are projected to increase the risk of diarrheal diseases in, for example, China. Climate change is also expected to affect the distribution of dengue fever and schistosomiasis, for example, it is projected that the latter will increase its distribution in northern China due to climate change.
Effects on ecosystems
Terrestrial systems in many parts of Asia have responded to recent climate change with shifts in the timing of blooming, growth rates and the distributions of plant species. Permafrost degradation, and future climate change are expected to further increase these impacts.
Large ecosystem changes may also occur in arid and semiarid areas with substantial impacts, but uncertainties in precipitation projections make these more difficult to predict, say the scientists.
Coastal and marine systems in Asia are under increasing stress from both climatic and non-climatic threats. Sea-level rise will probably contribute to coastal erosion, especially in the Asian Arctic, where rising sea levels are expected to interact with melting permafrost and a lengthening of the ice-free season. In South and Southeast Asia, mangroves, salt marshes, and seagrass beds may shrink due to sea-level rise, while coastal freshwater swamps and marshes will be vulnerable to saltwater intrusion. These are important habitats for a plethora of species, including many economically important fish species. Warming ocean temperatures and ocean acidification are expected to continue to damage coral reefs with substantial impacts on livelihoods and economies.
Earlier spring greening and longer growing seasons are expected to continue in humid temperate and boreal forest areas and this may increase the distribution of pests and diseases. Boreal forests are expected to expand northward and eastward at the expense of the tundra.
The permafrost is projected to decrease 20-90% by 2100 in North Asia and the Qinghai-Tibet Plateau, which will have substantial impacts to erosion, infrastructure, and livelihoods. Alpine vegetation may be largely replaced by forest or shrubland on the Tibetan Plateau. Snow leopard habitat in the Himalaya is expected to contract by up to 30% as forests replace open habitats.
Bamboo is projected to decline in the Qinling Mountains, with potentially adverse consequences for the giant pandas that rely on them for food.
In marine and coastal ecosystems, fish species are projected to shift their ranges northwards in response to rising sea surface temperatures. The combined effects of changes in distribution, abundance, and physiology may reduce the body size of marine fishes, particularly in the tropics and intermediate latitudes.