Chapter 2: Impacts A high priority goal, reinforced by world leaders at the World Summit on Sustainable development in Johannesburg in 2002, is ensuring that people have enough water for basic needs: water supply, sanitation, and food production. The challenge is enormous: over one billion people still lack access to safe water, and more than two billion lack safe sanitation. Slow progress is not acceptable, as more than three million people still die every year from avoidable water-related disease. Meeting this challenge will be made more difficult not only by socio-economic factors such as increases in population, but also by the upward trend in extreme weather and climatic events. Yearly economic losses from large events have increased ten-fold between the 1950s and 1990s.
The scientific analyses in Chapter 1 show conclusively that climate variability and climate change need to be mainstreamed into water resource planning and management. We saw there how present and predicted future climate patterns force water managers to re-evaluate the availability and reliability of future water supplies. What does that mean for the "clients": the men, women and children who depend on a safe supply of water for drinking, cooking, hygiene and basic sanitation; the farmers whose crops need timely and plentiful watering in the growing season; the industrialists whose machinery must be cooled and lubricated on a continuous basis; the power utilities whose hydroelectric turbines perform best with full reservoirs and whose thermal stations demand copious cooling water? And what of nature itself? How can the minimum river flows and seasonal volumes needed to sustain valuable aquatic ecosystems be guaranteed in this climate of uncertainty?
Figure 2.1 shows that although water-related climate extremes strike developed and less developed countries alike, their consequences are very different. In developed countries, the material flood losses continue to grow, while the number of fatalities decreases. For catastrophic floods in developing countries, particularly in Asia, the number of fatalities is still very high relative to the developed countries.
Population growth is a primary driver in virtually all development sectors. The availability of sustainable water supplies is also a crucial factor in most of them. Together, they condition the progress that any country can achieve towards the targets of poverty alleviation, sustainable development and good governance. It is an unfortunate fact that the nations that contribute most to the greenhouse gas concentrations driving climate change are not the ones that will suffer most from its consequences. Vulnerability is a function of location and capacity to cope. On both counts, it is the poor in the developing world who are hardest hit by storms flood and droughts, and by the longer term impacts of global warming and sea level rise. In this chapter, we look at what the climate predictions of Chapter 1 imply for the livelihoods of future populations and for the ecosystems on which so many people depend.
While there may be uncertainty over the scale of climate variability and change by 2015 (the first time horizon set for achieving Millennium Goals), there is no dispute about the increase in both precipitation variability and global temperature rise over the past years and this trend is very likely to continue (see Chapter 1). Evidence suggests that even small changes in the magnitude of extreme climate events have an exponential effect on losses, and so the increasing trend in the frequency and magnitude of these events could derail progress towards many of the Millennium targets.
Not all the prognoses are doom-laden. For example, climate change will affect the number of people at risk of hunger. Crops grow faster in a warmer climate, but they also need water at crucial times. According to a study by Fischer et al. (2002), the combined impact of climate change will be of global significance only if super-imposed in a situation with an already high level of under-nourishment (see section 2.3.4). In all other cases, with stabilising population levels and rapid economic growth, poverty, and with it hunger – though negatively affected by climate change – would become less prevalent than it is today.
Although figures show that at the global level the increase of water demands and uses is the determinant driver in what can be considered as a looming crisis, it must be pointed out that the relationship of humans with water is largely defined at the local level, with water being considered either as a resource or as an ecosystem. Global and even national indicators hide the obvious fact that for all beings, scarce water means survival and no water at all means death within a few days. In many stressed environments, the resource component in the demand/supply balance may, indeed, become the key issue if the resource is modified in total amount or in its temporal or spatial distribution by, for example, changes to mean climates and climatic variability.
It was in recognition of the immense challenges that humanity faces in creating a more equitable world, that the Millennium Development Goals were established to help promote sustainable development in developing countries throughout the world. The additional stress that will occur on society and nature due to climate variability and change will increase the challenge of achieving these goals.
Before looking at how water availability and reliability may affect the different water users, it is helpful to see how much water there is going to be.
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