DK Earth: Human Impact
Over six billion people live on planet Earth. As the population grows, we are taking more and more land to live and using more of the world?s natural resources. Many human activities also produce POLLUTION, which is damaging the Earth?s environment.
Since farming began, 10,000 years ago, many wild landscapes have been transformed to create fields for crops and raising animals. Swamps and coastal marshes have been drained. Forests have been felled and grasslands have been plowed. However, removing tree and plant roots that help to bind the soil can make the soil loose and crumbly. High winds may then blow it away, or heavy rain may wash it into rivers. In some areas, soil erosion has turned fertile farmland into barren wastes.
In the 1700s, the dawn of the industrial age revolutionized methods of manufacturing and made them more efficient. Since then, factories have been built all over the world. Factories consume huge amounts of natural resources and energy, and many give off chemical waste, which creates problems such as air and water pollution, and GLOBAL WARMING.
One of our main challenges is to find the right balance between using and conserving Earth?s natural resources. The human species dominates Earth in a way that no species has done before. Our demands for fuel, water, land, and food are beginning to place a strain on the planet?s limited resources. What makes us different from other species, however, is our ability to recognize these global problems and our inventiveness in doing something about them.
All over the world, factories, power plants, farms, businesses, and homes produce huge amounts of pollution by releasing chemicals and other substances that pollute, or dirty, the natural environment. As people?s use of energy and other resources grows, the Earth is becoming more polluted.
Industrial waste, sewage, and chemical pesticides from farms seep into streams and rivers. Cars, factories, and power plants burning fossil fuels give off fumes that pollute the air. Chemicals called CFCs (short for chlorofluorocarbons), used to make refrigerators and aerosol sprays, destroy the ozone layer, which protects us from harmful sunlight. Household and other waste buried underground pollutes the land.
Some kinds of pollution quickly disperse on the wind or are diluted by water. Other types, such as radioactive waste, stay poisonous for thousands of years. Plastics and other domestic garbage that are buried underground in landfill sites may take many years to rot away completely.
Around the world, scientists are investigating the damage caused by pollution. Governments have introduced controls that curb the pollution produced by industry and farms, and restrict the development of land, especially in rural areas. Everyone can help to reduce pollution by using energy carefully, and by recycling glass bottles, cans, plastic, and paper so that they can be reused. This helps to save precious natural resources and cuts down on waste and litter.
Global warming is the slow and steady rise in Earth?s temperature caused by a buildup of ?greenhouse gases? in the air due to pollution. Some experts predict temperatures will rise by 2.5?8.1F (1.4?4.5C) this century.
Global warming is caused by the increased level of carbon dioxide and other greenhouse gases in the atmosphere. These gases are released from car exhausts and when fossil fuels are burned in factories and power plants. Greenhouse gases also include CFCs from aerosols and old refrigerators, and methane from swamps, gas pipes, and rotting garbage.
Global warming will melt some of the polar ice caps, bringing greater risk of floods to low-lying and coastal regions worldwide. Heat waves, droughts, hurricanes, and torrential rain will become more common. To prevent global warming, many countries are now trying to reduce their output of carbon dioxide and use renewable energy sources.