Some farmers use forestland to grow cash crops, such as coffee or pineapples. Other activities that are destroying rain forests include mining, logging, farming and cattle ranching. They help control the world's climate. Burning and clearing rain forests releases carbon , and this causes the weather to become much hotter. Rain forests also reduce floods and help to prevent droughts , soil erosion, and air pollution .
Rain forests are the world's most important source of new medicines.
Many medicines, such as aspirin and heart disease treatments, come from rain forest plants. It is possible that a cure for cancer or AIDS will be found in a tropical rain forest someday. A rain forest cannot be replaced. When a rain forest has b een destroyed, it is gone forever. Once the web of interdependence has been broken, plants, and animals have no way to rebuild their complex communities.