Every animal and plant has an impact of some kind on the world. In most cases, the impact of any one organism is small, and felt only on a local scale. However, humans have the intelligence to use resources in new and different ways, and this has led to problems
It is hard enough for the earth to support all the human beings that are currently on it, simply in terms of feeding and housing them. However, that is not the extent of the problem, unfortunately. Human beings use many more resources than other animals, because our desires are not as simple as food and shelter. We also want clothes, houses, gourmet meals and much, much more. However, it is our technology that is hardest on the world.
Technological impacts come from several different areas. Fossil fuels create carbon dioxide when burned, which builds up in the atmosphere and changes the weather. Agricultural chemicals and pharmaceutical drugs enter ecosystems and change plant and animal growth and behavior. Direct human impact such as the desire for furniture, firewood and houses leads to logging faster than the trees can grow back.
Many organizations utilize a 'carbon footprint' to show people their effect on the world. This is practical because one of the major environment impacts of modern life is the production of CO2 through the burning of fossil fuels. As well as obvious things like driving a car, CO2 is also produced by trucks, planes and ships that move food and other goods, manufacturing plants that make pretty much everything around you, electricity generation stations, and much more.
Carbon footprint calculators take a set of information you give them and tell you where you fall. Some people choose to 'offset' their carbon footprint by giving money to organizations that plant trees which use CO2. Being aware of your impact on the earth and minimizing it wherever possible is the best long-term solution to the problem, however.
Reducing your environmental impact can take a number of different forms. The steps that most organizations tout include reducing overall energy use, which includes limiting the use of your car, electricity, and natural gas whenever possible. Purchasing power is also important, and buying local, sustainable, and organically produced goods has a positive impact on the environment.
Being green in this modern age can reward businesses with increased customer numbers and loyalty. People are coming to realize just how important being green is for future generations, and businesses often play a large part in the generation of carbon dioxide through manufacturing, shipping, and other costly tasks. Businesses that move to greener methods wherever possible are more appealing to people who want to have the minimum possible impact on the earth.