Answer:
1.It began about 30,000 years ago, reached its greatest advance 21,000 years ago, and ended about 10,000 years ago
2. Global warming has become a higher and larger risk.
3. Global warming
4. Carbon dioxide
5. Because of the fossil fuels that people are burning for energy.
6. Coal, oil and natural gas
7.Fossil fuels are made from decomposing plants and animals.
8.We depend on those fuels to heat our homes, run our vehicles, power industry and manufacturing, and provide us with electricity.
