Global Climate change represents one of the greatest challenges
facing society and freshwater resources today. It impacts key aspects of everyday
life and puts significant demands on global resources. Increases in population and
economic development have lead to increasing pollution, adding greenhouse gases
such as carbon dioxide, methane, nitrous oxides and fluorinated gases into the atmosphere,
intensifying the greenhouse effect. An increased greenhouse effect can lead to
climate change and global warming. Here, I explore how climate change effects
freshwater resources in China.
Water shortages could threaten China’s social and economic
development. Projected climate change could affect water availability across
China. China contains 20% of the worlds population but only 7% of its freshwater.
In 2014 eleven out of thirty-one
provinces did not meet the World Bank’s water needs criteria of 1500m3. Low water
pricing has bought on poor water management by disconnecting the market water
prices helping to increase wasteful usage in farming and industry and constant pollution
of the already scarce freshwater resources. A 2009 World Bank report stated that China was
using ten times more water per unit of production than the average
industrialised country. (Arden, 2017).
Climate change has exacerbated the situation. The Yellow and
Yangtze rivers are both fed by meltwater from the Tibetan Plateau. These rivers
both show differing trends but both are affected by climate change. The This is
a problem as they are a vital part of daily life of people in China. Rivers and
lakes are drying up and wetlands are disappearing.
How will availability of freshwater resources be impacted by
Precipitation and potential evaporation are the main
climatic drivers controlling freshwater resources. Climate change is likely to
have a major impact on China’s water resources by altering rainfall patterns
and increasing the frequency of long and severe droughts in certain areas. There
is more water in the south than in the north, were it is scarcer. Many areas of
the country lie in transition zones where water resources are already being affected
by climate change. Since the 1960s the Yangtze River has shown a small and
statistically insignificant increase in annual runoff, driven by increasing
precipitation. In the same period in the North, the Huanghe River has exhibited
a persistent decrease in runoff due to a decline in precipitation and substantial
As the climate warms the air becomes warmer. Warmer air can
hold much more water vapour. This can lead to more and heavier rainfall when
the air cools. Heavier rainfall leads to more rapid movement of water from the
atmosphere back to the oceans, reducing the ability to store and use it. Warmer
air also means that snowfall is replaced by rainfall, increasing evaporation rates.
Rapid climate change is shortening China’s rainy seasons and melting important
glaciers that feed the Yellow River.
China has to deal with increased and heavier rainfall events,
often leading to flash floods alongside adapting to a drying climate. Floodwater
will often produce many health problems because of damage to water supply
systems and insufficient drinking water supplies. However, the most serious
consequence of flooding is large scale contamination of drinking water. it can
become contaminated with microorganisms like bacteria, sewage, heating oil,
agricultural or industrial waste (Sun et al., 2016).
Glaciers will play a key role in determining runoff in the
future and a continuing increase in glacial runoff can be expected in response
to warming. However, uncertainties are large as it lies in the vulnerability of
Chinese glaciers to future warming. Runoff from the Tibetan Plateau’s mountains
feeds the largest rivers across Southeast Asia, including the Yangtze, Yellow,
Mekong, Ganges and Indus rivers. If glaciers continue to retreat and snowpack
shrinks atop the plateau, the water supplies of billions of people will be in
danger (Cyranoski, 2005). The exact timing and magnitude of the ‘tipping point’
of each glacier is still uncertain, the projected long-term exhaustion of
glacial water supply should have a considerable impact on the availability of
water for both agricultural and human consumption.
The most important victim in the climate system could be the
summer monsoon. Monsoons play an important role in determining local weather
conditions, including rainfall patterns. The impact of monsoon on the local
weather is different from place to place. In some places it’s just a question
of having a little more or less rain. In other places, it means serious flood
or 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 the
ocean. As the land surface absorbs more sunlight than the atmosphere, the
plateau creates a vast area of surface warmer than the air at that elevation,
increasing the land–ocean pressure gradient and intensifying the monsoon (Sylte,
Global warming would lead to a greater increase in the
plateau’s surface temperature than over the ocean, thus intensifying the
monsoon. However, aerosols that absorb solar radiation, and changes in land use
in the region, could weaken it. The questions are how much more change to
expect in the future, and how severe the effects will be on the planet’s
climate as a whole.
Climate Model Projections
According to the (IPCC, 2014) Fifth Assessment Report, it is
likely that area that experience the monsoon systems will increase over the 21st
century. Although monsoon winds are expected to weaken, monsoon precipitation
is likely to intensify die to the increase in atmospheric moisture.
In the next thirty years, the global climate model predicts
that eastern and central China will experience a hotter and drier climate. It is
predicted that the amount of accessible water could decrease by 20%. According
to the UKMO Hadley climate scenario (1960-2099) between 2061-2099, both air
temperature and rainfall are likely to increase significantly across China. While
more water will become available for most of China during the second half of
the century, northern China is anticipated to experience additional water
stress due to large increases in temperature. (Sun et al., 2002).
It Is difficult to estimate the impacts of climate change on
the future river flows in Chinas because there are many uncertainties in
climate projections and river management plans.
Glaciers will substantially influence water runoff in the
future, however our capacity to predict the effects of melting glaciers is
limited because only a few studies have addressed this issue.
China continues to over extract water for irrigation, industrial
and domestic usages is likely to increase as the human population expands and
becomes even richer.
Nationally the total amount of usable groundwater is about
2,800 km3 or half of annual precipitation, this is equal to 6% of global water
supply. Over 80% of China’s water supply is concentrated in the south east and
less than 20% is available in the northern regions. The northern areas have
experienced increasing levels of drought and groundwater supplies are almost
exhausted in the major cities like Beijing and Shanghai. Using historical
climate data, Liu and Fu (1996) concluded that northern and eastern China (35o
N or 113 o — 117o E) has warmed by 0.88 o C to 1.75 o C from the 1950s to
1980s. They found that precipitation had decreased for most part of the
country. A recent review (Jiang et al., 2000) concluded that streamflow in
China is somewhat sensitive to temperature change, and very sensitive to
precipitation. The dry northern regions that have been under serious water
resource stress as discussed earlier are more sensitive than the humid south.
To overcome uncertainties, other approaches should be used
together with Global Climate Models. The ‘analouge approach’ gives information that
is more specific than that given by the Global Climate Models by reconstructing
past climates for example precipitation and temperate in any given area. These can
be used to construct future scenarios by analogy.
Climate change has an adverse effect on water quality in China.
Changes in rainfall patterns, increases in frequencies of droughts and floods
have contributed to changes in river runoff, affecting main rivers like the Yangtze
and Yellow rivers. Glaciers also contribute to determining runoff as the Tibetan
Plateau feeds these major rivers.