When someone takes care of something that has been entrusted to them, they are practicing stewardship. Environmental stewardship means taking responsibility and being careful with natural resources and the natural systems we are part of. The idea of stewardship also recognizes the responsibility to hand these resources over to succeeding generations.
Some people act as stewards through their careers. We can call them professional stewards. Other people take care of natural resources in the ways that they live; they are also environmental stewards. We can call them practical stewards. Environmental stewardship is very important no matter how distant we might feel from natural systems. We are all part of ecosystems and depend on healthy functioning ecosystems for our survival and for the survival of future generations.
We know that matter cannot be created or destroyed. It can, however, be altered and dispersed. At any one time we have a finite supply of natural resources (such as fisheries, forests, water, minerals and fossil fuels) on our planet. If we contaminate them, or use them up faster than they are replaced, we will automatically defeat our ability to achieve sustainability.
Sustainability is a complex term to define and understand. The World Conservation Union - Caring For The Earth describes it as a way of doing things that "improves the quality of human life while living within the carrying capacity of supporting ecosystems." It recognizes that we must continue to live in and maintain these ecosystems for hundreds and thousands of years into the future. To achieve sustainability we must make decisions and conduct our lives based on how natural systems and cycles work.
For many, sustainability refers not only to the quantity of natural resources but to their quality as well. Quality, in this case, refers to purity of abiotic resurces and the genetic diversity of living things. Because natural systems are constantly changing, it is difficult to determine when an ecosystem is changing in a way that will harm it beyond repair. Most naturally occurring changes in ecosystems happen very slowly. Sometimes human activity cause those same changes to happen too rapidly.
Sustainability also includes improving the quality of life for all humans and their descendants. Therefore, it has social, economic and political implications. Conserving natural resources and sharing the benefits of natural resources more equitably throughout the planet are part of sustainability. Decisions about using natural resources are often difficult because the ecological, economic and social factors must all be weighed.
Stewardship can refer to using practices that promote sustainability. Let's look at the example of green plants. Green plants on land and in the oceans supply us with oxygen, help moderate temperatures on the planet, form the base of food chains and serve as storage reservoirs in hydrologic and nutrient cycles. Using up green plants faster than they can be replaced eventually leads to an imbalance in the system and creates problems for humans and other living organisms on the planet. When we recognize the roles natural resources play within our ecosystems and the dependance of all humans on them, we cannot help but recognize a call to stewardship.