The environment is a very important asset for man. It provides various materials to use, fresh air to breathe, food to eat, water to drink, and energy to use. With more human interactions and activities, we are harming the environments and climates around us. These harmful effects have negative consequences on our humans. For example, greenhouse gas emissions can lead to asthma and many other health problems and cause global warming. This is an example of a negative externality, that is, a cost that affects a party that has not chosen to bear that cost. Clearly, greenhouse gas emissions represent a negative externality for our economy, as people who have not chosen to bear the cost of emissions but are nevertheless affected by them. Individual consumers and businesses can reduce greenhouse gas emissions to their efficient levels without governments if property rights systems are exclusive (all benefits and costs should accrue only to the owner), transferable (the property rights could be transferred voluntarily from one owner to another) and enforceable (protected from seizure or involuntary encroachment). If property rights systems are exclusive, transferable, and enforceable, then the owner of a resource has an incentive to achieve the optimal level, because failure to do so results in personal loss. However, in the case of greenhouse gas emissions, it can be difficult to define exclusivity, transferability and/or enforceability. These greenhouse gas emissions are not caused by a single person, but by society as a whole. Almost everyone is responsible for emissions because we use electricity, heating and transportation almost every day. It is therefore very difficult to define property rights. Additionally, many people do not see or feel the consequences of greenhouse gas emissions. We all know that global warming causes sea ice and glacier coverage to decrease, leading to sea level rise, but we cannot understand the consequences. Maybe people who live near the coastline realize the consequences, but many still don't realize it. Therefore, people are not incentivized to achieve the optimal level because we see no personal influence.