Our study presents the future scenario of precipitation and temperature patterns in the Kabul River Basin. It shows that there will not only be gradual changes in the levels of precipitation and temperature, but there will also be a sharp rise in climatic extremes with pronounced changes in their magnitude and frequency. As communities tend to adapt poorly to climatic extremes, these changes will cause more harm to human health, food security, and the natural ecosystem compared to the gradual changes. Moreover, since the responses of the communities and the natural ecosystem will not be linear and intuitive in response to these extreme events, the impacts they will cause will be much more damaging. In this regard, taking into account the extreme climatic events that are likely to occur in the KRB in the future and considering the heterogeneous nature of their impact in terms of time, space, and individual, we discuss below the effects this will have on the four areas of health, agriculture, water resources, and the cryosphere (Table 7). Importantly, these sectors are not stand-alone – they are interlinked; so, any negative influence on them can lead to more stress on the social system in terms of adaptation, while there’s also the danger of unhealthy competition to gain access to the resources (Bowles et al., 2014)..
Human health
The KRB accounts for 35 per cent of Afghanistan’s population and has the fastest population growth rate compared to other parts of Afghanistan (MEW and World Bank 2013). The projected increase in heatwaves and summer days in the basin will lead to a surge in illnesses and deaths as the body’s ability to regulate its temperature gets compromised. This is likely to have both direct (in the form of escalating vector-borne diseases, illness, and death) and indirect (in the form of pathogenic activities and proliferation of bacteria) impacts on human health (Bowles, Butler, and Friel 2014; McMichael, Haines, Slooff, Sari Kovats, and Organization 1996). Some of the examples are of an increase in waterborne diseases in the United States (Curriero, Patz, Rose, and Lele 2001) and the Pacific Islands (Singh et al. 2001); and rise in deaths in France (Fouillet et al. 2006) and the US (Whitman et al. 1997) due to heatwaves, – more examples in Table 7. Along with climatic factors, non-climatic factors such as demographic distribution, socio-economic status, cultural conditions, adaptive capacity, and access to health care, play a key role (CCSP 2008). Here, it has to be noted that it is the vulnerable section of the population, like women, children, the elderly, and the differently abled people, would be at the higher risk of mortality rate.
Agriculture and food security
Cereals such as wheat, corn, barley, sorghum, rice, and potatoes, and other entities such as cotton, fruits, nuts, and grapes (Muradi and Boz 2018) are the major agricultural products in the KRB. The projected increase in summer days and heatwaves are bound to influence the cropping system (Iizumi and Ramankutty 2015), vegetative growth, fruiting, and grain production across species (Hatfield and Prueger 2015; Mbow et al. 2019). As for precipitation, the primary source of soil moisture, it influences photosynthetic activity (Mavi and Tupper, 2004) and the productivity of crops (Motha 2011), while the optimum temperature range determines the development or wilting of a plant (Backlund, Janetos, and Schimel 2008). Hence, any increase in extreme events will have a direct impact on the agriculture and food security of the basin. Studies in India have shown acceleration of senescence from extreme heat in the wheat (Lobell et al. 2012), and other studies from the United States (Table 7) have provided examples on the risksand uncertainties regarding crop production and food security.
Moreover, it is likely, any adverse impacts on agricultural productivity will have harmful effects on mental health and well-being; they will also lead to conflicts and compel unfair competition for the available natural systems. Then there’s the likelihood of increased migration of humans and other species, and invasion by alien species. Nonetheless, the aggregate impacts of climate change and extreme events on agricultural productivity are complex to be reliably quantified, mainly due to the difference in climate type and associated agriculture processes and productivity (Gornall et al. 2010).
Water resources and hydrology
The increase in temperature and decrease in winter and pre-monsoon precipitation in the KRB in the future are likely to influence the availability of water for household use and crop production. Likewise, as consecutive dry days increase and the precipitation days become more inconsistent, there’s more likelihood of droughts and floods (Tabari 2020); they will also influence hydropower generation and trigger changes in river flow, sediment load, and even in aquatic biodiversity (Whitehead, Wilby, Battarbee, Kernan, and Wade, 2009). Some examples from Kerala, the Colorado River, and Europe, as shown in Table 7, reflect the influences on the natural cycle of water due to extreme events. Although water is inherently flowing and continually being recharged (Oki and Kanae, 2006), the consistency, availability, and accessibility at a given location and time matter the most. Also, location-specific, efficient water resource management approaches will be affected.
Cryosphere
The future scenarios indicate that the temperature of the KRB will increase by 2.60C to 5.10C and that the basin will have fewer frost days. This will create additional vulnerability in of the cryosphere. There is likely to be a shift from the solid form of precipitation to the liquid form. The major glaciers in the north-western part of the basin are likely to decrease significantly. The examples (Table 7) from the Canadian Arctic show that rising temperatures have significantly affected the Arctic ecosystem, while in the Tibet region, glacier retreat has been detected. Similarly, changes in the patterns of ice melt, permafrost, and seasonally frozen ground are likely to affect the entire landscape of the basin, and also detract from its scenic appeal. This will also reduce slope stability, leading to natural hazards like landslide and erosion. Considering the heterogeneous nature of the KRB, only a detailed assessment of the components of the cryosphere and the mass balance in the basin can quantify the exact magnitude of the impacts.
Table 7
A few examples of the impact of extreme events on the sectors of health, agriculture, water resources, and the cryosphere.
Extreme Events
|
Examples/Probabilities of Sectoral Impacts/Implications
|
References
|
Health Sector
|
Extreme precipitation
|
• Based on 548 reported outbreaks of waterborne diseases from 1948 to 1994. Precipitation above the 90th percentile was followed by 51 per cent outbreak of waterborne diseases.
• 68 per cent of the waterborne diseases occurred after the 80th percentile of the precipitation event.
|
(Curriero et al. 2001)
United States
|
Extreme temperature
|
• During the most intense heat of July 1995, there occured 514 heat-related deaths (12 per 100,000 population). This is a 31 per cent increase above the baseline.
|
(Whitman et al. 1997)
Chicago, United States
|
Extreme temperature and precipitation
|
• Casualties took place even in tropical countries where people are more acclimatized to the hot climate.
|
(McMichael et al. 2008), United States
|
Extreme temperature
|
• Excess deaths of nearly 14,947 people in France in August 2003 had to do with heatwaves.
|
(Fouillet et al. 2006; Poumadere, Mays, Le Mer, and Blong 2005), France
|
Extreme temperature
|
• During the summer of 2003 in Europe, there occurred 70,000 additional deaths. This data was culled from 16 European countries.
|
(Robine et al. 2008)
European countries
|
Extreme temperature precipitation
|
• There was a statistically significant relationship between extreme temperature and diarrhoea cases from 1986 to 1994.
• Extreme rainfall was associated with statistically significant increase in diarrhoea cases in the same month, while the cases decreased in the following month.
|
(Singh et al. 2001) Pacific Islands
|
Extreme temperature
|
• Occurrence of heatstroke and dehydration, as well as cardiovascular, respiratory, and cerebrovascular diseases.
|
(Seneviratne et al., 2012), based on global data
|
Agriculture Sector
|
|
Extreme temperature and precipitation
|
• There was damage to the tune of nearly 1 billion US dollars due to weather-related disasters.
• The socio-economic costs of these extreme events are far-reaching and long-lasting.
|
(Motha 2011)
United States
|
Extreme heat
|
• Nine years of satellite measurement of crop response to temperatures greater than 34°C in northern India showed a negative impact on wheat growth and yield.
|
(Lobell, Sibley, and Ortiz-Monasterio 2012) India
|
Extreme temperature and precipitation
|
• There occurred 20–49 per cent variance in yield anomalies due to extreme climate events, which were largely attributed to temperature-related extremes.
• The regions that are particularly susceptible are North America (in the case of maize, spring wheat, and soy production) and Asia (in the case of maize and rice production).
|
(Vogel et al. 2019)
|
Extreme temperature
|
• Adverse effects on pollination in the case of crops like Zea mays L. and Brassica oleracea L.
|
(Hatfield and Prueger 2015), Iowa, United States
|
Extreme precipitation and increase in GHG emissions
|
• A shift in the agricultural production zones around the nation.
• Significant negative pressure on maize yields, farm production levels, and farmers.
|
(Rosenzweig, 2000; Rosenzweig, Tubiello, Goldberg, Mills, and Bloomfield 2002), United States
|
Water Resources and Hydrology
|
|
Extreme precipitation
|
• Extreme rainfall events increased the intensity and frequency of surface flow.
• The base flow was not largely impacted.
• Multi-year drought might increase and be more intense.
|
(Samuels, Rimmer, & Alpert, 2009) Jordan River
|
Extreme precipitation
|
• 66 years of climatic analyses show droughts in Kerala, India, but there was a flood in 2018.
|
(Mishra and Shah, 2018), India
|
Variability in precipitation and temperature patterns
|
• The average storage, seasonal distribution in the inflow, and the hydropower produced got influenced.
|
(Christensen, Wood, Voisin, Lettenmaier, and Palmer, 2004), Colorado River
|
Extreme temperature and variability in precipitation events
|
• Events with an intensity of today’s 100-year floods and droughts may re occur every 10–50 years during the 2070s in critical land area of Europe.
|
(Lehner, Döll, Alcamo, Henrichs, and Kaspar 2006), Europe
|
Cryosphere
|
|
Extreme temperature
|
• Extreme warming during the summer of 2008 showed the deepening of the permafrost active layer; loss of the ice-shelf area, perennial lake ice, and sea ice; loss of ice-dammed freshwater lakes; and the loss of the cryo-ecosystem.
|
(Vincent et al. 2009), Ward Hunt Island and its vicinity in the Canadian Arctic
|
Extreme temperature
|
• Snow-dominated watersheds will shift towards rain-dominated ones, resulting in high flows, especially during late autumn and winter rather than spring, and lower flows in summer.
|
(Clifton et al. 2018), Blue Mountains, Oregon, United States
|
Extreme temperature and precipitation
|
• Glacier retreat.
• Inconsistent changes in snow cover.
• Degradation of permafrost.
|
(Kang et al. 2010), Tibetan Plateau
|
Further, apart from these four sectors, the altered frequencies and amplitude of extreme events may change the demographic rates, fitness, and the community structure of species (Ma, Rudolf and Ma 2015); they will also have a bearing on wind-power generation due to changes in the intensity and duration of wind speed. There is also the probability of an increase in disasters and adverse changes in the aquatic ecosystem; meanwhile, the availability of timber and non-timber forest products, too, will be under threat This list of implications in the different sectors can be extensive but along with the relative value of change in any hydro-meteorological characteristics of a location; the spatial extent, location’s climatology, the adaptive capacity of the human and natural system also plays a crucial role in determining the impact of the change in that location (Meehl et al., 2000).