From nature to my backpack, and using resources wisely

Renewable resources, such as trees, crops, fish and water, can be replaced in a fairly short time. Nonrenewable resources, such as coal, oil and natural gas, take millions of years to form, so once they are used they are gone for us. But renewable does not mean unlimited. If people cut trees faster than new ones grow, or catch fish faster than they breed, the supply shrinks and shortages happen. Water can also be spoiled by pollution, and soil can be carried away by wind or water, which is called erosion. A shortage can make a resource cost more. Burning fossil fuels also adds pollution to the air. So we must plan for both kinds of resources, and use the renewable ones at a rate they can recover from.