In this paper the anthropogenic and also meteorological droughts will be discussed with the effects and problems they arise and how they may be affected by climate change. Additionally, two example cases namely Kazakhstan and South Africa demonstrate how these countries struggle with water stress and droughts. After this, droughts as a positive process response system will be examined to understand the areas that need to be considered when thinking about drought early warning systems and managing water stress due to drought events.
It is commonly acknowledged that the increasing population and economic growth lead to a growing water demand. Especially arid and semi-arid regions suffer from water stress, which is mainly caused by human activities. Since it is widely agreed on that water stress is man-made, it is interesting to discover what role climate change plays in the decrease of water resources and with it in detail the potential of causes for more severe drought events.
Sophie Stiebig 20 November 2020 Effects of climate change on drought events
It is commonly acknowledged that the increasing population and economic growth lead to a growing water demand. Especially arid and semi-arid regions suffer from water stress, which is mainly caused by human activities. Since it is widely agreed on that water stress is man-made, it is interesting to discover what role climate change plays in the decrease of water resources and with it in detail the potential of causes for more severe drought events. Therefore, the anthropogenic and also meteorological droughts will be discussed with the effects and problems they arise and how they may be affected by climate change. Additionally, two example cases namely Kazakhstan and South Africa demonstrate how these countries struggle with water stress and droughts. After this, droughts as a positive process response system will be examined to understand the areas that need to be considered when thinking about drought early warning systems and managing water stress due to drought events.
Firstly, it is important to understand the impact of human activity and its influences on the hydrological system. Due to “substantial growth in population, industrial and agricultural activities and [a change in] living standards” as Merhan et. al. (2017) present, especially semi-arid and arid areas are affected by growing water consumption. This leads to a decrease in water resources. Reasons for this are an increasing water demand by individuals and also due to growing water usage by the agricultural sector to maintain food security (Fereres et.al. 2011). This problem can be exemplified by considering the water resource situation in Kazakhstan. Kazakhstan is one of the Central Asian countries whose water resources will be less impacted by climate change but more due to anthropogenic factors. It is important to understand that it is not mainly climate change and rising temperatures that lead to water stress but also the distribution by governments. Therefore, it can be described as anthropogenic drought. Most of the water resources in Central Asia, about 90%, are used for watering and to ensure food security. With the growing population and therefore increasing demand for food, the water demand will increase by 30%, while the resources decrease by 30%. Since Kazakhstan’s water supplies are shared with other Central Asian regions it is a country that will be dealing with problems in their water resources. (Zhupankha et.al. 2018) leading to another sphere which is also involved, namely governmental decisions on water distribution. This perfectly demonstrates the effects anthropogenic activity has on water stress and how different countries are intertwined by different ideas of water contribution. The different motives by several interest groups enhance the problem of water distribution and lead to water scarcity. Therefore, “socio-political, cultural and economic dimensions of development…” (Vogel & Olivier 2017) play a major role as well in finding reasons for water stress.
Taking these anthropogenic reasons as starting point, one can begin to discover the effects human activity has on the hydrological system. With the increase of greenhouse gas emissions due to industrial progress and the going hand in hand with global warming it is resulting in growing surface heating. The warmer the surface gets the more water is evaporated, leading to more water vapor. The more moisture is evaporated, due to increasing temperatures, there is more potential for the drying out of surfaces (Trenberth et.al. 2013). Dried out soil results in drier conditions for vegetations, which are caused by drought. It is important to understand that droughts are not mainly caused by climate change but they are enhanced and becoming more severe (Vogel & Olivier 2017). Meteorological drought which results from shortages of precipitation and the previously discussed rise of temperatures, soil water drought, which is caused by the soils loss of infiltration ability and groundwater drought are deeply intertwined (Lanen et. al. 2019). If there is also already a shortage of moisture and water resources due to human activity it is more likely that the area will suffer from droughts events. Droughts can therefore be seen as a positive process response system which is amplifying the problems of the processes that lead to droughts (Fig.1).
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Fig. 1. Droughts as a process-response system (own illustration)
If there is a drought period with less or no precipitation over a certain period of time this leads to a shortage in water supplies, which results in drier surfaces. These surfaces have a higher albedo, leading to varying, rising temperatures. Plants do not have enough moisture in the soil which causes death of vegetation. Due to the loss of vegetation, evapotranspiration decreases which causes again less precipitation. If water stress lasts for a longer period the worst scenario would be desertification. Funk and Shukla (2020) therefore describe droughts as “slow-onset disasters” that develop slowly due to growing water stress because of a lack of knowledge about water distribution and additional low precipitation periods. The rising temperatures according to climate change do not create droughts, but they foster surface drying, resulting in a faster kick in and intensified and longer drought events (Trenberth et. al. 2013).
Furthermore, it will be discussed what effects drought events have on a specific region. South Africa for example has suffered from one of the severest drought events since 1930 in 2015. The country is located at the Tropic of Capricorn whose regions are mostly impacted by higher solar irradiance because of the angle of incidence of the sun’s radiation. The climate is also influenced by the moving of the Tropical Convergence Zone (ITCZ), which normally has an impact on the periods of heavy rainfall but also impacts drier periods. But not only the ITCZ influences the climatic conditions in South Africa, because especially drought events may be connected to ENSO events (Davis-Reddy & Vincent 2017). The reversal of the Walker circulation does not only affect mainly India and Australia, but also South Africa where it leads to drier condition and less precipitation (IPCC 2012). But not only in 2015 South Africa suffered from extreme heat waves, also in 2018 for example Cape Town had to deal with water stress. It resulted in the so-called “Day Zero” where the city’s water supplies were almost empty (Funk & Shukla 2020). It can be noticed that the quantity of severe drought events has been rising in the last decades. Not only vegetation and crops are suffering from these droughts, they also have severe effects on the population living in drought risk areas. In South Africa it had led to food insecurity due to a decrease in crop production and efficiency (Davis-Reddy & Vincent 2017). Because of the rise of food prices and the loss of jobs in the agricultural sector, families increasingly suffer from hunger. Especially the job loss leads to a rise in poverty, leaving mothers and their children with low nutritious or no food, starving to death. The rising temperatures increase these health struggles caused by poverty (Funk & Shukla 2020). Research has found that especially parts of Africa’s South have been heating up drastically over the last decades. Patterns show an increase of 0.4°C in a period of ten years, marked “by strong inter-annual and inter-decadal variability …” (Davis-Reddy & Vincent 2017). These trends and also previous heat stress events like in 2015 and 2018 show that South Africa will have to find ways to adapt to these severe circumstances and adjust their water resource management.
Not only ways of adaptation and adjustment need to be considered when dealing with drought events. It is also important to improve the use of “drought early warning systems” (DEWS) that can include the use of climate models or “satellite-enhanced weather observing systems” (Funk & Shukla 2020). Being able to predict possible scarcity of precipitation in some regions is inevitable to warn governments and adjust water resources. There also has to be a change in irrigation of crops that ensure an efficient scheme for irrigation without wasting water. Especially in dry regions it is important to prevent water from evaporating through subsurface irrigation. It is also necessary to understand that droughts and irresponsible water usage are resulting in an amplifying of surface heating and therefore also of climate change. This leads to a boosting vicious cycle. Ensuring drought resilience plays a major role in food security for the population. This also stresses the importance of DEWS to finding solutions quickly in order to limit negative fallouts due to the crisis (IPCC 2012).
Concludingly, it needs to be understood that climate change does not play the major role in the development of droughts. The severity of drought events may be caused through wrong watering processes, urbanization and a higher food demand due to a growing population. The effects of rising temperatures caused by a globally climatical change lead to an intensification and gravity of drought events. Man-made water stress and a decrease of precipitation are therefore intertwined. Once a region suffers from a drought event it can be noticed that it has a positive feedback effect, leading to more evaporation and therefore surface warming. It is important for semi-arid and arid areas to implement drought early warning systems and to build a strong drought resilience to ensure low consequences for their food and water security. Although drought events cannot be standardized and fully predicted countries that are vulnerable need to find ways to adapt to these recurring circumstances.
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- Quote paper
- Sophie Stiebig (Author), 2020, Effects of Climate Change on Drought Events, Munich, GRIN Verlag, https://www.grin.com/document/994821
