Fears over phosphorus supplies

" By 2030 demand for food will increase by 30 per cent and for water by 30 per cent, " said Guthrie. The report says that many countries were now using water unsustainably, by turning to desalination, which demands large amounts of energy, and by drawing on 'fossil' groundwater laid down millions of years ago. Libya, Algeria, and Saudi Arabia are taking vast quantities of fossil water from deep wells in the Sahara and Arabian deserts. " Eventually this resource will be depleted and alternative sources will be needed, " it says. The report looks at the whole water cycle and considers 'blue water' as that which comprises around 40 per cent of total rainfall and ends up in lakes, rivers and aquifers. Around 60 per cent of rainfall is 'green water' which is directly absorbed into the land. " This often results in green water being disregarded as part of water resource management. However, it has a vital role in maintaining delicate ecosystems and providing water for agriculture, " it says. The report also considers 'grey water', water that has been used once but can be used again for another purpose. " This can also be a significant resource; however, care must be taken that the water is suitable for the designated second use. " " In many regions, the demand for water is already much greater than the available supply. This affects developing countries where many people do not have access to safe water, and the developed world where burgeoning demand simply cannot continue to be met, " it says. The authors call on consumers to be aware of the water they were unwittingly using. " Changes in water consumption at an individual level will be crucial, " they say. And governments need to address the international trade in commodities that required large amounts of water to produce. Draining: The production of crops such as avocados in developing countries for export involves the loss of large amounts of water locally. (Picture: Photolibrary.) The short history of human exploitation of phosphorus is a dramatic one, ranging from the alchemist Hennig Brandt who discovered it in 1669 through to its dual use in the 20 th century. Phosphate fertilisers produced from mined minerals facilitated the rapid growth of agricultural production keeping pace with the exponential growth of world population, while weaponised phosphorus served in World War II fire bombs. A …