How Have Humans Damaged the Planet People have been living on Earth for about 200,000 years For most of that time the world population was less than a million people However about 10,000 years ago the population began to grow The Industrial Revolution By the 1800s the world population was more than one billion People in Europe and North America began to make steel and steam engines Steam engines helped build bridges railways and ships but they also caused pollution These machines released smoke and harmful gases into the air 쑼 Trees being cut down in a rain forest in Sumatra Felled forests take decades to recover 4
NOTHING NEW Humans were causing damage to the environment well before the Industrial Revolution Scientists think that hunting by humans as long as 45,000 years ago may have led to the extinction of mammoths saber-toothed tigers and other large animals 쑿 Mammoths disappeared about 10,000 years ago The main cause was probably human hunting The Twentieth Century The pollution of the air continued into the twentieth century as cars choked the roads and airplanes filled the skies Meantime by 1999 the human population topped six billion What Next In this book you will see how human activities are using up resources and damaging the earth You will also discover what steps people are taking to restore the natural environment WORLD POPULATION GROWTH BILLIONS OF PEOPLE 7 50 쑼 The world population has taken thousands of years to reach three billion but it has doubled to six billion in just forty years 6 79 6 06 4 44 1 86 1 65 0 98 0 79 1 26 0 30 0 31 0 40 0 50 3 02 2 30 0 1000 1250 1500 1750 1800 1850 1900 1920 1940 1960 1980 2000 2010 2020 5 7 5 7 0 6 5 6 0 5 5 5 0 4 5 4 0 3 5 3 0 2 5 2 0 1 5 1 0 0 5 0 s n o i l l i b n o i t a u p o P l
What Causes Air Pollution Burning fossil fuels is one of the main ways that we get energy We burn fuel to heat our homes to drive cars and to produce electricity in power plants Producing Smoke However burning fossil fuel is the main source of air pollution around the world It releases more smoke and gases into the air than any other human activity Other Sources of Air Pollution Oil refineries and steelworks also produce harmful gases that escape into the air Some factories such as paint manufacturers release deadly vapors into the atmosphere 쑼 Many power plants burn fossil fuels to create electricity The process releases smoke and harmful gases into the air 6
씱 This map shows areas of high carbon dioxide in red 5 miles above the earth CO2 from industrial areas rises and is moved by high-speed winds Gas and Smoke Air pollution is mainly smoke and different gases Smoke is made up of particulates tiny particles of burnt material It causes smog and makes it difficult for people to breathe However most air pollutants are gases INSIDE STORY Air pollution is not just an outdoor problem Tobacco smoke gases from cooking and vapors given off by paints and varnishes are some of the most common indoor air pollutants Carbon dioxide CO2 is the biggest pollutant It is given off whenever fossil fuel is burned So far humans have released more than 350 billion tons of CO2 into the atmosphere When some fossil fuels burn they release oxides such as nitrous oxide and sulphur dioxide These oxides are also major pollutants Persistent organic pollutants or POPs are produced by oil refineries and chemical plants They are harmful even in small amounts and they persist stay in the air Ozone is an active form of oxygen Gases from vehicle exhausts create ozone pollution 7
