Global Environment Outlook 3 (GEO 3)

3 8 2

OUTLOOK 2002–32

An index of 100 is the situation when total land area is undomesticated and all pressures are below the minimum threshold (see technical annex). Reduction in the Natural Capital Index indicates habitat loss and increasing pressure on terrestrial and aquatic biodiversity.

Population living in areas with severe water stress: North America (%)

Natural Capital Index: North America

50

100

2002

40

80

2002

30

60

40

20

20

10

0

0

Source: IMAGE 2.2 (see technical annex)

When more than 40 per cent of the renewable water resources of a river basin are being withdrawn for human use the river basin is considered to be under severe water stress. In many of the river basins of the western United States, home to over 100 million people, withdrawals currently exceed these limits.

may play a role here. In fisheries, greater cooperation both within the region and with other regions in Policy First and Sustainability First contributes to the preservation and restoration of important fish stocks. Some of the pressure on marine resources is reduced by the expansion of aquaculture in these scenarios, as well as in Markets First . The potential for international conflicts over marine resources within the region and with other regions is high in Security First , with negative implications for the health of aquatic ecosystems. Water withdrawals ease Certain areas of North America, particularly the southwest of the United States, are already subject to high levels of water stress. Without strong action to reduce water use, this is likely to grow with population increases and shifts in geographic distribution. Local policies, such as water pricing, can significantly affect demand. In addition, international policies related to agricultural trade can strongly affect crop type and therefore, irrigation requirements and water use. Advanced technologies, including biotechnologies to develop more water efficient crops and improve irrigation efficiency, can also have a striking effect. Total water withdrawals decrease under the Policy First and Sustainability First scenarios, where structural changes lead to reduced withdrawals in all sectors across North America.

Source: WaterGAP 2.1 (see technical annex)

Key to charts

Number of people living in areas with severe water stress: North America (million persons)

Markets First

200

Policy First

Security First

150

2002

Sustainability First

100

50

0

Source: WaterGAP 2.1 (see technical annex)

Under Markets First and Security First conditions, the number of people living in areas with severe water stress increases with population growth although there is a decline in percentage of population affected. Regulatory efforts in Policy First and Sustainability First lead to much more significant decreases in percentages as well as reductions in total numbers (see chart).