An alternative solution?

In this blog, there have been a variety of discussions on how to increase food production and make water use more efficient in order to meet food demands in Africa. This has been interlinked with the effect climate change has on food insecurity. These are all important but they only focus on improving food production. The concept of ‘virtual water’ is an alternative to these ideas. Virtual water is a term used to explain ‘how physical water scarcity in countries in arid regions is relaxed by importing water-intensive commodities.’ The concept is simple as it suggests that countries that have insufficient water resources should import high water demand crops to avoid this drain on their domestic water. As with all concepts, there are benefits and drawbacks.

Figure 1 below shows the virtual water balance by country and the major flows of virtual water. Focusing specifically on Africa, the northern and southern areas tend to import more virtual water than the lower latitude African nations. Much of northern and southern Africa is desert and this highlights their need to import water intensive crops. Importantly from this map, all the major flows of virtual water between countries avoid Africa entirely.

Figure 1: Virtual water balance by country and direction of major flows (1996-2005)

Virtual water in Africa

Virtual water is a key component of addressing food insecurity across Africa. African countries predominantly trade in virtual water with other African countries rather than the rest of the world. The biggest connection is between two southern African countries, Zimbabwe and South Africa. It is important to note that countries in Africa frequently trade with their neighbours. The connectedness between African countries is important because virtual water trades can be mutually beneficial and meet different needs in different countries. For example, countries can specialise in certain crops that grow well in their climate without having to worry about providing a variety of crops.

There is a tentative link between increasing openness to virtual water trade and decreasing undernourishment (which is a proxy for food security). This would suggest that virtual water security is an effective method for reducing food insecurity. Globally there is a trend that, as crop exports increase, water efficiency also increases but Africa is an anomaly to this trend. Because of this, the importance of virtual water is raised in Africa due to the shortcomings of other methods to reduce food insecurity. It is likely to be the case that funding is the key reason why water efficiency has not increased as much of the technology is too expensive for small-scale farmers.

A 2013 paper, suggested that virtual water imports may lead to overpopulation in some areas which may make these areas unsustainable. Increasing populations of areas with insufficient resources puts further strain on virtual water trade and leaves the population vulnerable to agricultural changes worldwide as they are reliant on crops produced in a variety of countries around the world. The MENA region (Middle East and North Africa) has been identified as a region where overpopulation is driving an increase in food demands and thus increased food insecurity. Population has quadrupled between 1950 and 2000. In addition, there has been poor water management and declining water quality. This illustrates that countries should not be over-reliant on virtual water trade.

Overall, it is clear that virtual water has a key role to play in meeting water and food demands in Africa. It is vital to remember that it is not a complete solution and over-dependence of virtual water trade can bring about other problems such as over-population. Africa as a continent does not have to be entirely reliant on increasing food production and raising efficiency levels to meet food and water demands, virtual water trade can help too.

Food insecurity in South Africa

Early on in this blog I discussed some of the issues surrounding the current drought in South Africa. Since then, the drought has worsened and food supplies are critically low. There has also been a shortage of donor funds to support people, partly as a result of droughts having very slow impacts that can often pass donors by. The drought has led to extreme food shortages leaving many families suffering.

A paper by Kamara and Sally (2004) in Development Southern Africa investigates some of the potential water management options with regard to food security in South Africa. Although it was written in 2004, it still has relevance to the present day. The paper highlights the link between water security and food security in poor households, emphasising the need to ensure good water supply. One of the biggest problems for South Africa in this regard is the low physical productivity in agriculture and low irrigated crop yields. The low productivity of crop growth points to one key problem, the fact that South Africa is simply unable to produce enough food especially when droughts occur.

The majority of South Africa’s water use is for the agricultural sector, much like other countries around the world. In order to manage water better, this is the sector that therefore needs to be targeted with more sustainable and equitable water use. A number of different techniques to achieve this, such as drip fed irrigation, have been mentioned in previous posts.

Figure 1: Dry crops in South Africa

The paper discusses a model called Podium which is a ‘decision support tool for testing policy options that aim at striking a balance between water allocations for food production on the one hand, and for satisfying domestic, industrial and environmental needs on the other hand.’ This model is intriguing as it attempts to balance the importance of different demands within a country. The model incorporates many different aspects of water usage and water availability. This form of water management may be particularly useful in a country such as South Africa which struggles with water availability due to climate and few large river catchments in their territory.

One alternative to improving water usage is to address food insecurity through food aid. However, a paper by del Ninno et al. (2008) suggests that food aid is not very effective at reducing food insecurity in Africa and instead private markets can often been more efficient at providing food for those that need it the most. Importantly, it is the fact that food aid is poorly targeted and often has other costs associated (such as administration costs). If these could be addressed then food aid would be far more successful but only as a short term solution during periods of severe shortage as consistent food aid could reduce the desire of a country like South Africa to grow its own food.  

Between water management, the Podium model, food aid and markets, there are many solutions to deal with problems of food insecurity in South Africa and other African countries. The success of these is however dependent on how effectively they are implemented and who they benefit.

Food security and climate change

I recently watched this video highlighting the link between climate change and food insecurity in West Africa. The news clip explores a number of different aspects of this link, talking about drought and flood resistant crops, whether climate change is seen as a big issue and the effect of climate change on Africa relative to the rest of the world. A key point raised was that incidents of climate related issues in sub-Saharan Africa have gone up tenfold over the last 30 years. The impacts of climate change are going to have the greatest impacts on Africa and this means food security is going to be severely affected.

Physiology of plants and climate change

I thought it would be interesting to look at plants at a physiological level to see what impact climate change is having on them. This is of great importance for farmers and scientists to assess how crops may adapt to climate change and this is likely to have implications for crop yields and the management of farms into the future. Climate change brings about changes in temperature, atmospheric carbon dioxide levels and rainfall levels and frequency. These have impacts on the physiology of plants in a variety of different ways.

C₃ and C₄ crops

Below shows the two different forms of uptake of carbon dioxide by plants. The majority of plants fix the atmospheric carbon dioxide with the C₃ pathway such as wheat, rice and soybean. The C₄ pathway is where carbon dioxide is concentrated internally. There are fewer plants that use the C₄ pathway, these include maize, sorghum and sugarcane. The process of photorespiration, which occurs alongside photosynthesis, is where plants take up some oxygen and release some CO₂ back to the atmosphere. Photorespiration occurs more in C₃ plants as the rate of photorespiration in C₄ plants is almost zero. The impact of climate change is therefore more likely to be on C₃ crops with increased photosynthesis due to higher CO₂ levels as well as a suppressed oxygenation process. The C₄ crops are less likely to respond to changes in CO₂ because ‘these plants have an internal mechanism that concentrates CO₂ internally.'

Figure 1: C₃ and C₄ plants

Energy balance

Under the influence of climate change, the net energy balance of plant leaves will change. Increases in temperature will lead to a greater loss of water because of a vapour pressure deficit. This will increase the amount of water lost by plants and the amount of water the plant consumes to meet these losses. Despite this, rises in atmospheric carbon dioxide would actually decrease the amount of water lost by leaves because stomatal conductance would decrease as a result of these stomata remaining openfor a shorter period of time. The actual amount of water used by the plant will still be reliant on the amount of water supplied to the leaf through precipitation and irrigation. This means that the frequency of rainfalls and the availability of irrigation are still very important to crop growth.

Soil surface wetness

In areas where there is low canopy cover, such as large crop fields, soil surface wetness determines the amount of water used. If the surface of the soil is dry, this increases water consumption as there is a higher vapour pressure deficit. This subjects crops to harsher conditions which negatively impacts growth. In hot African regions such as the Sahel, this is likely to be a key issue and with the impacts of climate change into the future, the demand for water for crops is expected to increase. With rainfall also becoming more sporadic and intense, the need for irrigation techniques is greater than ever.

Impacts for farmers and the provision of food in Africa

A study in southern Africa investigated the response of crops to climate change. The paper suggested that the positive effects of carbon dioxide may be able to offset the potential negative impacts on crops of climate change. These feedbacks are important to consider and because they are highly spatial variable, it is very difficult to predict the impacts. This study also suggested that by the time we reach the latter half of the 21^st century, the fertilising effects of carbon dioxide may not be able to make up for the other negative effects. Therefore climate change may have a more long term impact on crop yields and the system may actually be able to adapt in the short term.

I believe this post has emphasised the importance of effective irrigation in Africa. There are a variety of physiological changes to plants caused by climate change and these are more likely to affect future food scarcity than existing scarcity. To adapt to increasing water loss, crops will need to be irrigated more intensively but this requires access to sufficient water resources and the technology to extract it.