Will Human Civilization Face the Exhaustion of Water Resources Due to Global Change

The climate had always been changing and will continue to evolve in the future. So far the only acceptable conception has been based on the outputs of IPCC [12], which declare that warming up of the Earth is caused by anthropogenic activities -specifically by emissions of carbon dioxide. But a series of scandals disclosed a specialized handling of the primary data so that the seriousness of the so far achieved results was challenged or even damaged. Nevertheless, the ever present question, which the public should ask with regard to climate change is, whether the planet will ever run out of water and similarly if fossil fuels would ever be exhausted. Therefore, to simply compare the exploitation of water resources with deposits of crude oil, coal and earth gas is evidently not correct. The volume of water existing on the Earth is stable and is estimated to attain 1,386,100,000 km3 [13], and has never changed. Nevertheless, due to great dynamics of water the spatial distribution of water and/or its state on the Earth are changing. In contrast to estimates based on the concept of global warming, then it is to be emphasized, that cooling of the Earth would paradoxically have much more devastating impact on water resources. The ocean water level during the last Ice Age was by 120 m lower than it is nowadays. This huge volume of water was contained in glaciers so that this water did not participate in the water cycle.

As a consequence, cooling would result in a decrease of atmospheric precipitation and the subsequent expansion of arid areas. It is not a chance that the largest area without precipitation is Antarctica and not the Sahara Desert. The problem is that the civilization will not be threatened by a shortage of water in the near future but by its irregular distribution over the planet far from ideal to suit mankind.

As emerges from WHO [14] data, around 1.1 billion people globally do not have access to improved water supply sources, whereas 2.4 billion people do not have access to any type of improved sanitation facilities. About two million people die every year due to diarrheic diseases and most of them are children less than 5 years of age. When using just simple calculations some very alarming figures arise- the world population is growing but the volume of water remains the same so that the number of countries suffering from water scarcity will gradually increase. The WRI in 1998 predicted that the number of people suffering from water scarcity should increase from 3.7% in 2000 to 8.6% in 2025 and even up to 17.8% in 2050.

Let us ask ourselves a question - what is water scarcity? To define this concept the most frequent term is the "Water stress index" [15]. These authors proposed 1,700 m3 of renewable water resources per capita per year as the threshold, based on an estimate of water requirement in the household, agricultural and energy sectors, and the needs of the environment. Countries whose renewable water supplies cannot sustain this figure are said to experience water stress. When water supply falls below 1,000 m3, a country experiences water scarcity, and below 500 m3, absolute scarcity.

Presently there are six countries that can be placed in the category of "absolute water scarcity". They include: Kuwait 30 m3/person, United Arab Emirates 174 m3/ person, Libya 275 m3/person, Saudi Arabia 325 m3/person, Jordan 381 m3/person and Singapore 471 m3/person. The category of countries suffering from water scarcity closes with Israel with 969 m3/person. Apart from almost fatal water scarcity the great majority of these countries are doing well by having a high standard of living. For comparison the United Kingdom has 3,337 m3 at one's disposal.

On the other hand, there are countries, which from the viewpoint of water supply are on the verge of humanitarian crisis, namely Somalia and Nigeria Somalia has at one's disposal 3,206 m3 water per person and Nigeria even 5,952 m3.

It is evident that we have to distinguish two types of water scarcity - Physical and Economic. A total of 96% of countries [16] have sufficient water resources so that problem is not in physical water scarcity but in water mismanagement and poverty.

It is known that the largest volume of water is used in agriculture. While in Europe ca 30% of total consumption is used in farming, in developing countries this figure is often in excess of 90%. Major reserves exist that can be demonstrated on water management in Israel. The water balance between atmospheric precipitation and consumption is fluctuating around the verge so that only the less water demanding crops are grown in Israel and the efficiency of "drip irrigation" became a world model. The large part of agricultural production in high demand for water is resolved by importation of these crops. This method allows covering 87% of corn consumption so that it actually imports 1,000 L of so-called virtual water in one ton of imported corn. This is one of the methods of fighting water scarcity - to take advantage of the global market and to grow water demanding crops in countries with favorable climatic conditions.

Perhaps one of the most dramatic examples of the reverse approach is the ecological disaster of the Aral Lake caused by the meaningless attempt to grow cotton in the semi-desert regions of Tajikistan and Uzbekistan in the 1960s and 1970s.

Nevertheless, similar problematic projects exist even nowadays. Irrigation in the Indian state of Andhra Pradesh is dependent on limited groundwater resources with the exception of the monsoon season. Regardless of these unfavorable climatic conditions this state has focused on the cultivation of rice at the cost of huge loss due to evapotranspiration caused by temperatures exceeding 40°C. Government subsidies for drilling wells and particularly the free water abstraction and free electricity consumption for pumping groundwater result in overexploitation of water resources and dramatic lowering of the groundwater level.

One of the possible ways to resolve the issue of water scarcity is desalinization of sea water. On a global scale only 0.2% of potable water and 2.4% of industrial water are presently covered by desalinization of sea water. The main reason for this negligible proportion is the cost associated with desalinization which uses the three most common technologies- thermal distillation, freezing, and reverse osmosis, all of which are highly energy demanding. The cost of production of 1,000 L of potable water varies around 0.5 USD, while expenditures related to the production of industrial water are roughly half the cost [17]. It is obvious that desalinization of sea water can hardly be employed in poor African countries. On the other hand Lomborg [18], reports that only 0.5% of global GNP would be enough to cover worldwide consumption of water obtained by desalinization of sea water. This clearly shows great perspective of water scarcity solution.

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  • kauko
    Why water is getting exhausted?
    4 months ago

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