In 2002 the International Food Policy and Research Institute used a computer model to examine the implications of three alternative futures for global water (and food) supply and demand.
Clearly the business as usual scenario will be
unsustainable in the long term.
The most worrying scenario is that of water crisis, which shows how mismanagement of water resources or climate change could threaten our water and food supplies and lead to wider geographical problems including conflict.
Some features of this scenario may be beginning to occur already.
Climate Change
The impacts of global warming on water supply are easier to examine if we focus on the two most obvious features of current climate change – higher global temperatures and increasingly extreme weather events.
Increases in mean annual temperature are already leading to earlier snowmelt in mountain areas and this is causing increase in spring discharge in major river basins.
This water will be
lost to the oceans
or evaporated, as
present water
management
cannot store or
use it effectively.
Snowfields in the Andes are already disappearing as rainfall replaces snowfall – this means the loss of a primary source of water.
Melting of Himalayan glaciers could threaten water supplies of nearly half the
world’s population in Asia.
Cyclones and monsoon events threaten water supplies intermittently, but it is the shortages of water
brought about by the increased frequency and intensity of drought that will have the most devastating impacts.
Dried-up rivers, irrigation failure and depleted aquifers threaten the lives of millions of people in Asia
andmsub-Saharan Africa.
Business as usual
Water changes by 2025
Water scarcity will
reduce food production
Consumption of water
will rise by over 50%
Household water use will increase by 70% (mostly in developing countries)
Industrial water demand will increase in developing countries
Wider impacts
Developing countries will become reliant on food imports and experience increased hunger and malnutrition.
In sub-Saharan Africa, grain imports will more than triple. In parts of western USA., China, India, Egypt and north Africa, water will be pumped faster than aquifers can recharge
Water crisis
Water changes by 2025
Global water consumption will increase, mostly for irrigation
Worldwide, demand for domestic water will fall
Demand for industrial water will increase by 33% over business as usual levels, yet industrial output will remain the same
Wider impacts
Food production will decline and food prices, especially cereals, will increase rapidly.
In developing countries malnutrition and food insecurity will increase.
Dam building will decline and key aquifers in China, India and north Africa will fail.
Conflict over water between and within countries will increase
Sustainable water
Water changes by 2025
Global water consumption and industrial water
use will have to fall considerably.
Environmental flows
could be increased
dramatically compared
to other scenarios
Global rain-fed crop yields could
increase due to improvements in
water harvesting and use of
sustainable farming techniques
Agricultural and household water prices might double in
developed countries and triple in the developing world
Wider impacts
Food production could increase slightly and shifts occur in where it is grown.
Prices could fall slowly.
Investment in crop research, technology and water-management reforms will increase.
Unsustainable pumping of groundwater should end.
Governments could delegate farm management to community groups