World population scenarios
Some factors (such as global population growth) will begin to decline in importance and others (distribution of people, climate change, and changes to nutrient cycles) will gain more importance in the near future.
30 Nov 2007 - by Philippe Rekacewicz, Emmanuelle Bournay, UNEP/GRID-Arendal
Trends in productivity 1981-2003 (greening and land degradation)
Unsustainable practices in irrigation and production may lead
to increased salinization of soil, nutrient depletion and erosion.
An estimated 950 million ha of salt-affected lands occur
in arid and semi-arid regions, nearly 33% of the potentially arable
land area of the world. Globally, some 20% of irrigated
land (450,000 km2) is salt-affected, with 2,500–5,000 km2 of
lost production every year as a result of salinity (UNEP, 2008).
02 Feb 2009 - by Hugo Ahlenius, UNEP/GRID-Arendal
Dissolved phosphate levels: concentrations at river mouths
Phosphorus is naturally present in water, primarily as inorganic and organic phosphates. Phosphates can enter aquatic environments in several ways: from the natural weathering of minerals in the drainage basin, from biological decomposition, or as runoff from human activity in urban and agricultural areas.
A comparison of the major watersheds between the two decades showed that northern Europe and North America had lower phosphate concentrations...
26 Jan 2009 - by Phillippe Rekacewicz, February 2006
Nitrate levels: concentrations at river mouths
Nutrients are essential to life. In aquatic systems, nitrogen and phosphorus are the two nutrients that most commonly control the growth of aquatic plants, algae and bacteria. Nitrogen and phosphorus are considered to be the primary drivers of eutrophication of aquatic ecosystems, where increased nutrient concentrations lead to increased primary productivity. Some systems are naturally eutrophic, whereas others have become eutrophic as a result o...
26 Jan 2009 - by Philippe Rekacewicz
Industrial areas and seasonal zones of oxygen depleted waters
This graphic illustrates the strong link between areas with high densities of industrial activity and zones of seasonally oxygen-depleted waters.
There is a strong link between areas with high densities of industrial activity and zones of seasonal oxygen-depleted waters. In recent years there has been an increasing focus on treating and reducing municipal and industrial waste, and on reducing nitrogen levels in agricultural runoff. However, less...
26 Jan 2009 - by Phillipe Rekacewicz, (Le Monde diplomatique) February 2008