to ecosystem degradation, and undermined the processes that support ecosystems and the provision of a wide range of ecosystem services essential for human well-being.
e Millennium Ecosystem Assessment, an international assessment by more than
1,300 scientists of the state of the world’s ecosystems and their capacity to support hu- man well-being, identified agricultural expansion and management as major drivers of eco- system loss and degradation and the consequent decline in many ecosystem services and human well-being (www.maweb.org). Analyses illustrated that by 2000 almost a quarter of the global land cover had been converted for cultivation (map 6.1), with cropland cover- ing more than 50% of the land area in many river basins in Europe and India and more than 30% in the Americas, Europe, and Asia. e Millennium Ecosystem Assessment also showed that the development of water infrastructure and the regulation of rivers for many purposes, including agricultural production, often resulted in the fragmentation of rivers (map 6.2) and the impoundment of large amounts of water (figure 6.1; Revenga and oth- ers 2000; Vörösmarty, Lévêque, and Revenga 2005).
Many scientists argue that as a society we are becoming more vulnerable to environ- mental change (Steffen and others 2004; Holling 1986), reducing our natural capital and degrading options for our current and future well-being (Jansson and others 1994; Arrow and others 1995; MEA 2005c). Natural and human-induced disasters, such as droughts and famine, are also likely to increase the pressure on vulnerable people, such as the rural poor, who depend most directly on their surrounding ecosystems (Silvius, Oneka, and Verhagen 2000; WRI and others 2005; Zwarts and others 2006).
Furthermore, as populations and incomes grow, it has been estimated that food de- mand will roughly double by 2050 and shift toward more varied and water-demanding diets, increasing water requirements for food production (see chapter 3 on scenarios).
Extent of cultivated systems in 2000
Note: Cultivated systems are dened as areas where at least 30% of the landscape is in croplands, shifting cultivation, conned livestock production, or freshwater aquaculture.
Source: MEA 2005c.