AbstractGlobal Climate change represents one of the greatest challengesfacing society and freshwater resources today. It impacts key aspects of everydaylife and puts significant demands on global resources. Increases in population andeconomic development have lead to increasing pollution, adding greenhouse gasessuch as carbon dioxide, methane, nitrous oxides and fluorinated gases into the atmosphere,intensifying the greenhouse effect. An increased greenhouse effect can lead toclimate change and global warming. Here, I explore how climate change effectsfreshwater resources in China.
IntroWater shortages could threaten China’s social and economicdevelopment. Projected climate change could affect water availability acrossChina. China contains 20% of the worlds population but only 7% of its freshwater. In 2014 eleven out of thirty-oneprovinces did not meet the World Bank’s water needs criteria of 1500m3. Low waterpricing has bought on poor water management by disconnecting the market waterprices helping to increase wasteful usage in farming and industry and constant pollutionof the already scarce freshwater resources. A 2009 World Bank report stated that China wasusing ten times more water per unit of production than the averageindustrialised country.
(Arden, 2017).Climate change has exacerbated the situation. The Yellow andYangtze rivers are both fed by meltwater from the Tibetan Plateau. These riversboth show differing trends but both are affected by climate change. The This isa problem as they are a vital part of daily life of people in China.
Rivers andlakes are drying up and wetlands are disappearing.How will availability of freshwater resources be impacted byclimate change?Rainfall patternsPrecipitation and potential evaporation are the mainclimatic drivers controlling freshwater resources. Climate change is likely tohave a major impact on China’s water resources by altering rainfall patternsand increasing the frequency of long and severe droughts in certain areas. Thereis more water in the south than in the north, were it is scarcer. Many areas ofthe country lie in transition zones where water resources are already being affectedby climate change. Since the 1960s the Yangtze River has shown a small andstatistically insignificant increase in annual runoff, driven by increasingprecipitation.
In the same period in the North, the Huanghe River has exhibiteda persistent decrease in runoff due to a decline in precipitation and substantialwater use. As the climate warms the air becomes warmer. Warmer air canhold much more water vapour. This can lead to more and heavier rainfall whenthe air cools. Heavier rainfall leads to more rapid movement of water from theatmosphere back to the oceans, reducing the ability to store and use it.
Warmerair also means that snowfall is replaced by rainfall, increasing evaporation rates.Rapid climate change is shortening China’s rainy seasons and melting importantglaciers that feed the Yellow River. FloodsChina has to deal with increased and heavier rainfall events,often leading to flash floods alongside adapting to a drying climate. Floodwaterwill often produce many health problems because of damage to water supplysystems and insufficient drinking water supplies.
However, the most seriousconsequence of flooding is large scale contamination of drinking water. it canbecome contaminated with microorganisms like bacteria, sewage, heating oil,agricultural or industrial waste (Sun et al., 2016).
GlaciersGlaciers will play a key role in determining runoff in thefuture and a continuing increase in glacial runoff can be expected in responseto warming. However, uncertainties are large as it lies in the vulnerability ofChinese glaciers to future warming. Runoff from the Tibetan Plateau’s mountainsfeeds the largest rivers across Southeast Asia, including the Yangtze, Yellow,Mekong, Ganges and Indus rivers. If glaciers continue to retreat and snowpackshrinks atop the plateau, the water supplies of billions of people will be indanger (Cyranoski, 2005). The exact timing and magnitude of the ‘tipping point’of each glacier is still uncertain, the projected long-term exhaustion ofglacial water supply should have a considerable impact on the availability ofwater for both agricultural and human consumption.MonsoonsThe most important victim in the climate system could be thesummer monsoon. Monsoons play an important role in determining local weatherconditions, including rainfall patterns. The impact of monsoon on the localweather is different from place to place.
In some places it’s just a questionof having a little more or less rain. In other places, it means serious floodor drought. In summer, the Tibetan plateau heats up more than the Indian Ocean,leading to a pressure gradient and the flow of the air and moisture from theocean. As the land surface absorbs more sunlight than the atmosphere, theplateau creates a vast area of surface warmer than the air at that elevation,increasing the land–ocean pressure gradient and intensifying the monsoon (Sylte,2016).Global warming would lead to a greater increase in theplateau’s surface temperature than over the ocean, thus intensifying themonsoon.
However, aerosols that absorb solar radiation, and changes in land usein the region, could weaken it. The questions are how much more change toexpect in the future, and how severe the effects will be on the planet’sclimate as a whole.Climate Model ProjectionsAccording to the (IPCC, 2014) Fifth Assessment Report, it islikely that area that experience the monsoon systems will increase over the 21stcentury. Although monsoon winds are expected to weaken, monsoon precipitationis likely to intensify die to the increase in atmospheric moisture.In the next thirty years, the global climate model predictsthat eastern and central China will experience a hotter and drier climate. It ispredicted that the amount of accessible water could decrease by 20%. Accordingto the UKMO Hadley climate scenario (1960-2099) between 2061-2099, both airtemperature and rainfall are likely to increase significantly across China.
Whilemore water will become available for most of China during the second half ofthe century, northern China is anticipated to experience additional waterstress due to large increases in temperature. (Sun et al., 2002). It Is difficult to estimate the impacts of climate change onthe future river flows in Chinas because there are many uncertainties inclimate projections and river management plans.Glaciers will substantially influence water runoff in thefuture, however our capacity to predict the effects of melting glaciers islimited because only a few studies have addressed this issue.
China continues to over extract water for irrigation, industrialand domestic usages is likely to increase as the human population expands andbecomes even richer.Nationally the total amount of usable groundwater is about2,800 km3 or half of annual precipitation, this is equal to 6% of global watersupply. Over 80% of China’s water supply is concentrated in the south east andless than 20% is available in the northern regions. The northern areas haveexperienced increasing levels of drought and groundwater supplies are almostexhausted in the major cities like Beijing and Shanghai. Using historicalclimate data, Liu and Fu (1996) concluded that northern and eastern China (35oN or 113 o — 117o E) has warmed by 0.
88 o C to 1.75 o C from the 1950s to1980s. They found that precipitation had decreased for most part of thecountry. A recent review (Jiang et al., 2000) concluded that streamflow inChina is somewhat sensitive to temperature change, and very sensitive toprecipitation. The dry northern regions that have been under serious waterresource stress as discussed earlier are more sensitive than the humid south.
To overcome uncertainties, other approaches should be usedtogether with Global Climate Models. The ‘analouge approach’ gives information thatis more specific than that given by the Global Climate Models by reconstructingpast climates for example precipitation and temperate in any given area. These canbe used to construct future scenarios by analogy. Conclusion Climate change has an adverse effect on water quality in China.Changes in rainfall patterns, increases in frequencies of droughts and floodshave contributed to changes in river runoff, affecting main rivers like the Yangtzeand Yellow rivers. Glaciers also contribute to determining runoff as the TibetanPlateau feeds these major rivers.