The study also indicates that the natural wealth of the earth's forests, freshwater, and marine ecosystems has declined by one third since 1970. Greenhouse Emissions Rising Emission of greenhouse gases in the United States increased by 0.8 percent last year, according to the Department of Energy. Scientists believe that CO2 and other chemicals trap heat in the atmosphere and are responsible for global warming. Without a medical miracle, almost all of these millions will be dead by 2010. The epidemic will change Africa's demographics by reducing life expectancy, raising mortality, lowering fertility, creating an excess of men over women, and leaving millions of orphans behind.
Infection rates vary by country.
In Zimbabwe, Swaziland, and Lesotho, nearly one quarter is infected. In Namibia, South Africa, and Zambia, the figure is 20 percent. Four out of every 10 people currently live in river basins that are experiencing water scarcity. Many freshwater species are facing rapid population decline or extinction as well. More than 20 percent of the world's known 10,000 freshwater fish species have become extinct, threatened, or endangered in recent decades.