Let me show you some of them
Population Growth（人口增长）
Increasingly large numbers of people are being added to the world every year. As the number of people increases, more pollution is generated, more habitats are destroyed, and more natural resources are used up. Even if new technological advances were able to cut in half the environmental
impact that each person had, as soon as the world's population size doubled, the earth would be no better off than before.
The Population Division of the United Nations predicts that the 5.63 billion humans alive in 1994 will increase to 6.23 billion in the year 2000,
8.47 billion in 2025, and 10.02 billion in 2050. In fact, because larger
amounts of resources per person are used in the developed nations, each citizen from the developed world has a much greater environmental impact than does a citizen from a developing country.
Global Warming（全球变暖）
This process is referred to as the greenhouse effect.
These greenhouse gases, primarily carbon dioxide, methane, nitrous oxide, insulate the earth's surface, helping to maintain warm temperatures. If the concentration of these gases were higher, more heat would be trapped within the atmosphere, and worldwide temperatures would rise.
Air pollution（空气污染）
A significant portion of industry and transportation is based on the burning of fossil fuels, such as gasoline. As these fuels are burned,
chemicals and particulate matter are released into the atmosphere. These chemicals interact with one another and with ultraviolet radiation in sunlight in various dangerous ways. Smog, usually found in urban areas with large numbers of automobiles, can cause serious health problems.
Water pollution（水污染）
Estimates suggest that nearly 1.5 billion people lack safe drinking water and that at least 5 million deaths per year can be attributed to waterborne diseases. Point sources discharge pollutants at specific locations-from, for example, factories, sewage treatment plants, or oil tankers. Non point
sources- for example ,runoff water containing pesticides and fertilizers from acres of agricultural land -are much more difficult to control. Pollution arising from nonpoint sources accounts for a majority of the contaminants in streams and lakes.
Species Extinction（物种灭绝）
What is clear is that species are dying out at an unprecedented rate; minimum estimates are at least 4000 species per year, although some scientists believe the number may be as high as 50,000 per year. The
leading cause of extinction is habitat destruction. At the current rate at which the world's rain forests are being cut down, they may completely disappear by the year 2030.
As habitats are destroyed and species lost, the world is increasingly losing threads from the interconnected fabric of life.
These are 10 kinds of extinct animals in recent decades. They died out because of environmental degradation and human hunting. 桑吉巴尔豹。毛里求斯蚺蛇。 斯皮克斯金刚鹦鹉。金蟾蜍。夏威夷蜜旋木雀。马德拉大白凤蝶。提可巴鳉鱼。比利牛斯山羊。西非黑犀牛。爪哇虎
Chemical Risks（化学成分污染）
Many industrially produced chemicals may cause cancer, birth defects, genetic mutations, or death. Although a growing list of chemicals has been found to pose serious health risks to humans, the vast majority of substances have never been fully tested.
There is only one earth with super living conditions in the universe. It is no doubt that the nature is important to every human being. No nature, no life. I think we can’t prevent environmental degradation, but we can slow down it.
So what can we do to protect our globe? I leave this question to everyone, you can think about it after class.
第二篇：环境污染的演讲稿
环境（Environment）
Like all other living beings, humans have clearly changed their environment, but they have done so generally on a grander scale than have other species. Some of these changes-such as the destruction of the world's tropical rain forests to create grazing land for cattle or the drying up of almost three-quarters of the Aral Sea, once the world's fourth-largest freshwater lake, for irrigation purposes-have led to altered climate patterns, which in turn have changed the distribution of species of animals and plants.
Scientists are working to understand the long-term
consequences that human actions have on ecosystems, while environmentalists-professionals in various fields, as well as
concerned citizens in the United States and other countries-are struggling to lessen the impact of human activity on the natural world.
Population Growth（人口增长）
Increasingly large numbers of people are being added to the world every year. As the number of people increases, more pollution is generated, more habitats are destroyed, and more natural resources are used up. Even if new technological
advances were able to cut in half the environmental impact that each person had, as soon as the world's population size doubled, the earth would be no better off than before.
The Population Division of the United Nations predicts that the
5.63 billion humans alive in 1994 will increase to 6.23 billion in the year 2000, 8.47 billion in 2025, and 10.02 billion in 2050. In fact, because larger amounts of resources per person are used in the developed nations, each citizen from the
developed world has a much greater environmental impact than does a citizen from a developing country.
Global Warming（全球变暖）
This process is referred to as the greenhouse effect.
These greenhouse gases, primarily carbon dioxide, methane, nitrous oxide, insulate the earth's surface, helping to maintain warm temperatures. If the concentration of these gases were higher, more heat would be trapped within the atmosphere, and worldwide temperatures would rise.
Depletion of the ozone layer（臭氧层变薄）
The ozone layer, a thin band in the stratosphere （a layer in the upper atmosphere）, serves to shield the earth from the sun's harmful ultraviolet rays
In the 1970s, scientists discovered that the layer was being
attacked by chlorofluorocarbons （CFCs）, chemicals used in refrigeration, air-conditioning systems, cleaning solvents, and aerosol sprays.
Air pollution（空气污染）
A significant portion of industry and transportation is based on the burning of fossil fuels, such as gasoline. As these fuels are burned, chemicals and particulate matter are released into the
atmosphere. These chemicals interact with one another and with ultraviolet radiation in sunlight in various dangerous ways. Smog, usually found in urban areas with large numbers of automobiles, can cause serious health problems.
Water pollution（水污染）
Estimates suggest that nearly 1.5 billion people lack safe drinking water and that at least 5 million deaths per year can be attributed to waterborne diseases.
Point sources discharge pollutants at specific
locations-from, for example, factories, sewage treatment plants, or oil tankers.
Nonpoint sources-runoff water containing pesticides and fertilizers from acres of agricultural land, for example-are much more difficult to control. Pollution arising from nonpoint sources accounts for a majority of the contaminants in streams and lakes.
Species Extinction（物种灭绝）
What is clear is that species are dying out at an unprecedented rate; minimum estimates are at least 4000 species per year, although some scientists believe the number may be as high as 50,000 per year. The leading cause of extinction is habitat destruction, particularly of the world's richest
As habitats are destroyed and species lost, the world is increasingly losing threads from the interconnected fabric of life.
Chemical Risks（化学成分污染）
Many industrially produced chemicals may cause cancer, birth defects, genetic mutations, or death. Although a growing list of chemicals has been found to pose serious health risks to humans, the vast majority of substances have never been fully tested.
Environmental Racism（环境歧视）
Studies have shown that not all individuals are equally
exposed to pollution. Three of the five largest commercial hazardous waste landfills in America are in predominantly black or Hispanic neighborhoods, and three out of every five black and Hispanic Americans live in the vicinity of an
uncontrolled toxic waste site. The fact that the wealth of a community is not nearly as good a predictor of
hazardous-waste locations as is the ethnic background of the residents reinforces the conclusion that racism is involved in the selection of sites for hazardous-waste disposal.
Environmental racism takes international forms as well. Dangerous chemicals banned in the United States often
continue to be produced and shipped to developing countries. Additionally, the developed world has shipped large amounts of toxic waste to developing countries for less-than-safe disposal.