The litter, garbage, demands on fresh water supplies and deforestation for development all has an impact on the environment. This does not even include the impact that the constant exposure to humans has on the so-called wild animals. Yet, the Serengeti is another example where the protected park could not survive economically without the support of the tourist's currency.
Columbia University's Earth Institute is an example of an organization that is trying to cross international borders in order to promote overall sustainability. Sustainability is the environmental idea of making a much less dramatic impact on an environment by gauging all actions like food production, water consumption and development. Since the Earth Institute is interested in the study of all of Earth's systems, the idea of the sustainability of tourism is something that they have conducted research on. Another one of the Earth Institute's projects is to conduct research on some of the correlations between poverty and environmental degradation. The goal of Earth Institute is to improve the environment by improving the quality of life for Earth's poorest billions. Their idea is that if you take care of people's needs, they are much more likely to take care of the environment.
Another aspect of the idea of sustainable tourism is to limit the development of an area so that native plants, persons, and animals can coexist. In this new model for tourism, instead of humans maximizing the development of an area that is interesting to tourists, the idea is that development remains limited. That way, humans can still enjoy the natural area without killing or damaging the area that they came to enjoy. Limits are set on the amount of development that can happen, and these guidelines are enforced by local governments. Although not as much money will be generated using this model, the idea is that the natural area becomes a permanent part of the landscape rather than being something that will disappear once tourist have degraded the area and ruined the natural landscape.