An ecosystem is a living system that includes the sun as an energy source, soil, rocks, water, air, plant life and living beings. We humans are only one part of any ecosystem, but many people believe that we have a disproportionate effect. Our actions tend to affect not just our surroundings, but the world at large. To live more responsibly on the Earth, we must understand how the things we do can have lasting effects.
While people who live in towns and cities may not ever see the farms that support them, we are all dependent on agriculture. That agriculture has a huge effect on our ecosystems: pesticides and other toxic chemicals used in food production can wash downstream, killing many types of animals, polluting our waterways and even making humans ill. Fertilizers can wash downstream, causing "blooms" or large populations of algae and bacteria, which can harm fish populations. In addition, GreenFacts states that we are depleting fish populations in the oceans and seas, causing us to fish further offshore and deeper underwater as more and more fish disappear.
Throughout the world, 2.6 billion people lack proper sanitation, which means that drinking water around the world is contaminated with waste and disease. The World Health Organization (WHO) estimates that this has resulted in 1.8 million human deaths. Open water is often contaminated by agricultural chemicals, fuel from passing boats and even trash and litter. Both the Pacific and the Atlantic oceans contain large "islands" of plastic trash, which National Geographic suggests came from litterbugs and open landfills around the world.
We use natural resources to produce power, but according to the WHO, our current methods are harmful to ecosystems. Burning fuels such as wood and coal creates pollution, and is depleting our forests. The WHO claims that wood harvesting in rural areas is not only bad for human health, but is creating a "wood fuel scarcity." Worse, coal plants produce enough pollution that it is collecting in our atmosphere, causing breathing hazards and affecting the weather. Burning gasoline in our cars creates smog in and around cities.
Biodiversity is the variation between types of plants and animals. Every living thing plays a part in an ecosystem, and when a specific type of being becomes extinct or is removed from an area, its ecosystem suffers. When humans convert an area to farmland, we make it inhospitable to many types of plants and animals, and begin growing only the species we like best. Large-scale fishing, land development and many other practices drive out native species, changing the local ecosystem permanently.
The Earth's natural climate is always changing, but in years recent to 2010 we have observed dramatic changes that are likely due to humans. In fact, the United Nations Convention on Climate Change defines climate change as "change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere." Our industry, agriculture and pollution all have real effects on the Earth's natural systems. Pollution and greenhouse gases in particular are accumulating in our atmosphere, causing the planet's overall temperature to rise. This results in weather changes, which affect all ecosystems.