We saw in our previous lesson on climate change impacts, that anthropogenic climate change could profoundly influence fresh water availability around the world.
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What, if any, measures could we take to adapt to these changes? Possible adaptations can, in fact, be found on both the supply side and the demand side.
Let us first consider some supply side options. Fresh water could, for example, be transported from regions that are likely to see more precipitation to those likely to see less. The required transport (which costs both money and energy!) could be minimized by exploiting the fact that in many cases such regions are reasonably near to each other, e.g., tropical Africa (more runoff) vs. south Africa (less runoff), or the Pacific northwest (more runoff) vs. desert southwest (less runoff) of U.S., or Northern Europe (more runoff) vs. southern Europe and Mediterranean (less runoff). Other possibilities involve greater exploitation of groundwater sources, though this faces the challenge of over-tapped aquifers, which is already a problem in the U.S. Desalinization makes sense, particularly for coastal regions of the U.S., Australia, and Mediterranean which are predicted to dry, and where a nearby saltwater source would help minimize transportation costs. Desalinization is currently highly expensive and extremely energy intensive, making it a prohibitive source of freshwater today. However, as water resources diminish and technology improves, it is possible that desalinization will become a more viable option in the future. See table below for other possible supply side solutions.
What about the demand side? More efficient recycling of water and better conservation of water resources is an obvious approach. Both constitute what are often referred to as no regrets approaches — a concept we will encounter later in the context of climate change mitigation. Such actions not only cost us nothing, but they could in fact provide benefits, e.g., lower household water bills! Similarly, more efficient means of irrigation of crops could save water and provide other benefits as well.
Another possibility is the idea of tradable water access rights. This too has an analogy with climate change mitigation, since one approach that has been suggested for reducing carbon emissions is to allow individual companies limited numbers of permits for emitting and then letting them trade and sell them. The same thing could be done for rights to water resources. The idea behind this is that the efficiencies of the free market will, at least in principle, find the most cost efficient means of meeting water resource needs, since those with excess fresh water would be motivated to sell their valuable water rights to others willing to pay a premium for them.
|Supply Side||Demand Side|
|Prospecting and extraction of water||Improvement of water-use efficiency by recycling groundwater|
|Increase of storage capacity by building reservoirs and dams||Reduction in water demand for irrigation by changing the cropping calendar, crop mix, irrigation method, and area planted|
|Desalination of sea water (via reverse osmosis systems)||Reduction in water demand for irrigation by importing products|
|Expansion of rain water storage||Adoption of indigenous practices for sustainable water use (drawing upon local cultural knowledge in establishing efficient practices)|
|Removal of invasive, non-native vegetation from river margins||Expanded use of water markets to reallocate water to highly valued areas|
|Transport of water to regions where needed||Expanded use of economic incentives, including metering, and pricing to encourage water conservation|
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