About WATCH Outreach
WATCH was funded under the European Union’s Sixth Framework Programme and ran from
1st February 2007 to 31st July 2011
The methods and data sets developed in WATCH allow us to make estimates of past and future global water availability. But, it is only when we bring this together with the demand for water that we can begin to identify and quantify where there are deficits – where water scarcity is a problem – and areas where water might be more plentiful. Water scarcity occurs when there is not enough water available to meet the demands of agriculture, industry, and domestic use. To identify such areas, WATCH has quantified water use in these sectors and has assessed the drivers that will influence usage in the future.
The work goes beyond the climatic causes of change in the water cycle by also looking at the socio-economic influences that impinge on water availability and scarcity. For example, in many regions, population is set to increase at a rate that will put far greater demands on water resources than any of the changes that are associated with climate change. The outputs of WATCH will help policy makers to take informed decisions; to identify water-rich areas that have the potential to produce and export more food, and to anticipate where intervention may be needed in the future.
The WATCH approach to assessing water use by rainfed and irrigated agriculture makes a distinction between “blue” and “green” water. The blue part is water that has been withdrawn from rivers, lakes, reservoirs and groundwater for use in irrigation schemes. The green water is the moisture stored in the soil from rainfall. It has been demonstrated that about two thirds of global crop production relies on green water, which constitutes about 90% of the total agricultural water consumption.
A WATCH study using results from 17 climate models has quantified current and future green and blue agricultural water use and water scarcity. It is the first time that blue and green water use in agriculture have been calculated at a scale of 0.5 degree x 0.5 degree and over such long time periods (up to 2100). WATCH has also compared water availability with the water needed to produce a balanced diet for a country’s inhabitants (3,000 kcal per person per day – the hunger alleviation target – with an assumed 20% share of animal products). A key result is that climate change alone is likely to decrease the availability of both green and blue water in a number of countries, while at the same time, in some regions more water will be required for growing each unit of food. Thus, more areas will be affected by water scarcity in the future, and some countries will lose their capacity to produce the food needed to feed their population. If population growth is considered in addition to climate change, even more countries are at risk of losing food self-sufficiency.
Listen to Richard Harding, Co-leader of WATCH, introduce “Reconciling availability and demand”.