Green Times (Jun. 2014) - Page 5


Pollution may muddy landscapes, poison soils and waterways, or kill plants and animals. Humans are also regularly harmed by pollution. Long-term exposure to air pollution, for example, can lead to chronic respiratory disease, lung cancer and other diseases. Toxic chemicals that accumulate in top predators can make some species unsafe to eat. More than one billion people lack access to clean water and 2.4 billion don’t have adequate sanitation, putting them at risk to many diseases.

Litter in the world’s oceans comes from many sources, including containers that fall off ships during storms, trash that washes off city streets into rivers that lead into the sea, and waste from landfills that blows into streams or directly into the ocean.

Human activities contaminate ecosystems around the world—from pole to pole, from the highest mountains to the ocean deep. Toxic chemicals can be found in pristine forests and the blood of Arctic animals. Litter floats beneath the surface of oceans miles away from land. Even excess noise and light are interrupting natural patterns and disrupting the lives of animals and people.


Deforestation is a particular concern in tropical rainforests because these forests are home to much of the world’s biodiversity. For example, in the Amazon around 17% of the forest has been lost in the last 50 years, mostly due to forest conversion for cattle ranching. Deforestation in this region is particularly rampant near more populated areas, roads and rivers, but even remote areas have been encroached upon when valuable mahogany, gold and oil are discovered.

Deforestation can happen quickly, such as when a fire sweeps through the landscape or the forest is clear-cut to make way for an oil palm plantation. It can also happen gradually as a result of ongoing forest degradation as temperatures rise due to climate change caused by human activity. While deforestation appears to be on the decline in some countries, it remains disturbingly high in others and a grave threat to our world’s most valuable forests still remains.

Forests help to mitigate carbon dioxide and other greenhouse gas emissions, but they become carbon sources when they are cut, burned or otherwise removed. Tropical forests hold more than 210 gigatons of carbon, and deforestation represents around 15% of greenhouse gas emissions.

But when deforestation or degradation occurs, that balance can be thrown off, resulting in changes in precipitation and river flow.

Without trees to anchor fertile soil, erosion can occur and sweep the land into rivers. The agricultural plants that often replace the trees cannot hold onto the soil.