The 20th century's 10 warmest years all occurred in the last 15 years of the century. The rising temperatures are expected to raise sea levels, change rainfall, and other climate conditions. Changing the climate could change forests, crops, and water supplies. It might affect our health, or the health of animals including possibly endangering species or making them become extinct. Entire ecosystems could be permanently changed. These could be the effects of global warming.
<Tab/>The National Academy of Sciences says the Earth's surface temperature has risen about 1 degree Far…
