the past few centuries in different spheres—involving both natural and human components—that have contributed to global environmental change. The human population has tripled during the past century, greenhouse gas emissions have escalated, and the global temperature has risen, bringing greater nitrogen fixation and flux to coastal zones. In turn, these changes have created an enormous loss of biodiversity and species extinction in land and sea.

Oswald Spring noted that natural ecosystems produce an abundance of services on which humans depend. For instance, populations rely on provisioning services, or products obtained from ecosystems (such as food, water, and air); supporting services, or processes needed for the production of all other ecosystem services (such as the nutrient, sulfur, and carbon dioxide [CO2] cycles); and regulating services, or benefits that are obtained from ecosystem regulation (such climate regulation and water purification, which are crucial for discussions on global environmental change). One other area that often gets lost in the discussion is the cultural component, or the immaterial benefits obtained from ecosystems related to cultural heritage. She noted that human health is at the center of all these services, because human well-being is impacted by changes in ecosystems that directly or indirectly affect good social relations, material minimums, security, freedom, and choice.

Ecosystem Changes

Oswald Spring stated that experts are seeing unprecedented changes in the world’s ecosystems. During the past 30 years, increasing fresh water stress and water pollution have occurred throughout the world. In the past several decades, 20 percent of the world’s coral reefs were lost and another 20 percent were degraded. In addition, 35 percent of the mangrove forests, which are considered the most biodiverse areas on earth, were lost during this same period. The amount of water in reservoirs has quadrupled since 1960,1 withdrawals from rivers and lakes have doubled in the same time period, and today most surface water (70 percent worldwide) is used for agriculture (Millennium Ecosystem Assessment, 2005a). All of these processes have changed the world’s ecosystems and the services they provide.

These changes have related costs, Oswald Spring noted. Extinction rates among mammals, birds, and amphibians are 1,000 times higher than what was seen in the fossil record (Millennium Ecosystem Assessment, 2005b). Soil degradation is also increasing worldwide, which has implications for food production and water availability given that healthy


1 More reservoirs have been built since 1960. Water in reservoirs may be used to supply drinking water, generate hydroelectric power, provide irrigation, support recreational activities, and other uses.

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