Unit 9 Lesson 4 Human Impact on the Atmosphere Copyright © Houghton Mifflin Harcourt Publishing Company 1

Unit 9 Lesson 4 Human Impact on the Atmosphere Florida Benchmark SC.7.E.6.6 Identify the impact that humans have had on Earth, such as deforestation, urbanization, desertification, erosion, air and water quality, changing the flow of water. Copyright © Houghton Mifflin Harcourt Publishing Company 2

Air: What Is It Good For? Why is the atmosphere important? Unit 9 Lesson 4 Human Impact on the Atmosphere Air: What Is It Good For? Why is the atmosphere important? Air is an important natural resource. The air you breathe forms part of Earth’s atmosphere. The atmosphere is a mixture of gases that surrounds Earth. Copyright © Houghton Mifflin Harcourt Publishing Company 3

Why is the atmosphere important? Unit 9 Lesson 4 Human Impact on the Atmosphere Why is the atmosphere important? The atmosphere provides gases that organisms need to survive, including oxygen and carbon dioxide. Air is considered an important natural resource because animals, and humans, need air to breathe and thus to survive. The atmosphere absorbs harmful high-energy radiation coming from space. Copyright © Houghton Mifflin Harcourt Publishing Company 4

Why is the atmosphere important? Unit 9 Lesson 4 Human Impact on the Atmosphere Why is the atmosphere important? The atmosphere keeps Earth warm. Without the atmosphere, temperatures on Earth would not be stable. The greenhouse effect is the way by which certain gases in the atmosphere absorb and reradiate thermal energy. Copyright © Houghton Mifflin Harcourt Publishing Company 5

Unit 9 Lesson 4 Human Impact on the Atmosphere What is air pollution? The contamination of the atmosphere by pollutants from human and natural sources is called air pollution. Air pollution can come from natural sources, such as volcanic eruptions, wildfires, and dust storms. In cities and suburbs, most air pollution comes from the burning of fossil fuels. Industrial emissions is an example of a human source of air pollution. Copyright © Houghton Mifflin Harcourt Publishing Company 6

Unit 9 Lesson 4 Human Impact on the Atmosphere What is air pollution? Air pollution can be classified as gases such as carbon monoxide, sulfur dioxide, and ground-level ozone. Air pollution can also be classified as particulates. Particulates consist of tiny particles of solids that are suspended in air or water. The particulates from vehicle exhaust are a major cause of pollution in cities. Copyright © Houghton Mifflin Harcourt Publishing Company 7

It Stinks! What pollutants can form from vehicle exhaust? Unit 9 Lesson 4 Human Impact on the Atmosphere It Stinks! What pollutants can form from vehicle exhaust? Vehicle exhaust is a common source of air pollution in urban areas. Ground-level ozone is produced when sunlight reacts with vehicle exhaust and oxygen in the air. Although ozone in the ozone layer is necessary for life, ground-level ozone is harmful. Copyright © Houghton Mifflin Harcourt Publishing Company 8

What pollutants can form from vehicle exhaust? Unit 9 Lesson 4 Human Impact on the Atmosphere What pollutants can form from vehicle exhaust? Vehicle exhaust is the main ingredient in smog. Smog is a brownish haze that forms when ground-level ozone and vehicle exhaust react in the presence of sunlight. Copyright © Houghton Mifflin Harcourt Publishing Company 9

What pollutants can form from vehicle exhaust? Unit 9 Lesson 4 Human Impact on the Atmosphere What pollutants can form from vehicle exhaust? Smog can damage the lungs and irritate the eyes and nose. Copyright © Houghton Mifflin Harcourt Publishing Company 10

How does pollution from human activities produce acid precipitation? Unit 9 Lesson 4 Human Impact on the Atmosphere How does pollution from human activities produce acid precipitation? Precipitation such as rain, sleet, or snow that contains acids from air pollution is called acid precipitation. Burning fossil fuels releases sulfur dioxide and nitrogen oxides into the air. When these gases mix with water in the atmosphere, they form sulfuric acid and nitric acid. Copyright © Houghton Mifflin Harcourt Publishing Company 11

How does pollution from human activities produce acid precipitation? Unit 9 Lesson 4 Human Impact on the Atmosphere How does pollution from human activities produce acid precipitation? Sulfuric acid and nitric acid are strong acids. They can make precipitation so acidic that it is harmful to the environment. Copyright © Houghton Mifflin Harcourt Publishing Company 12

How’s the Air? What are measures of air quality? Unit 9 Lesson 4 Human Impact on the Atmosphere How’s the Air? What are measures of air quality? Air quality is the measure of how clean or polluted the air is. As pollution increases, air quality decreases. Two major threats to air quality are vehicle exhausts and industrial pollutants. Copyright © Houghton Mifflin Harcourt Publishing Company 13

How can air quality affect health? Unit 9 Lesson 4 Human Impact on the Atmosphere How can air quality affect health? Daily exposure to small amounts of air pollution can cause serious health problems. Certain people, such as children, elderly people, and people with health problems, are especially vulnerable to the effects air pollution. Short-term effects include coughing, headaches, and wheezing. Long-term effects include lung cancer and emphysema. Copyright © Houghton Mifflin Harcourt Publishing Company 14

Things are changing How might humans be changing Earth’s climates? Unit 9 Lesson 4 Human Impact on the Atmosphere Things are changing How might humans be changing Earth’s climates? As a result of burning fossil fuels, the atmosphere today contains about 37 percent more carbon dioxide than it did in the mid-1700s. Average global temperatures have also risen in recent decades. Copyright © Houghton Mifflin Harcourt Publishing Company 15

What are some predicted effects of climate change? Unit 9 Lesson 4 Human Impact on the Atmosphere What are some predicted effects of climate change? Many changes on Earth have already been linked to higher temperatures. Changes in rainfall patterns and rising sea levels will have many negative effects on life on Earth. Such changes will likely have political and economic effects on the world. Copyright © Houghton Mifflin Harcourt Publishing Company 16

How is the ozone layer affected by air pollution? Unit 9 Lesson 4 Human Impact on the Atmosphere How is the ozone layer affected by air pollution? Earth’s protective ozone layer is thinning over the polar regions, allowing more harmful ultraviolet radiation to reach Earth’s surface. Chemicals called chlorofluorocarbons (CFCs) cause ozone to break down. CFCs once had many industrial uses, but now they are banned. However, CFCs released in the atmosphere decades ago will stay there many more decades, breaking down more ozone. Copyright © Houghton Mifflin Harcourt Publishing Company 17