Effects of Climate Change LESSON 3 - WordPress.com · 2016-08-16 · Vocabulary coral bleaching ... increase vegetation, since plants use carbon dioxide in photosyn- ... climate change

Global Climate Change 497

Do You think that global warming is something that may happen in the future? Climate change is affecting the world right now. Ecosystems are changing, and individual organisms are experiencing the effect of those changes. Climate change has also affected people, including how people make their living and even some people’s health.

Effects on Ecosystems and organisms

As the atmosphere warms, ecosystems on land and in the ocean are changing, affecting organisms in various ways.

Think of the ways in which temperature and climate are important to eco-systems and individual organisms. For example, temperature and rainfall both affect animals’ food supplies. When the climate changes, the lives of organisms usually change too. The following examples demonstrate this.

Shifting habitats As ecosystems on land become warmer, the loca-tions in which some organisms live are changing. The habitats of some plants and animals have shifted to places where the climate is cooler—toward the North and South poles or higher up on mountains. For example, in the Santa Rosa Mountains in California, the location of some plant species, such as the Jeffrey pine tree and California lilac, has shifted upward an average of about 65 meters (215 feet) (Figure 11).

LESS

ON 3Effects of Climate Change

FIGURE 11 Changing Range In some places, California lilacs (Ceanothus) are growing higher on mountainsides than they once did.

• State ways in which the warming atmosphere affects ecosystems and organisms.

• Explain how climate change is affecting people now.• Predict future effects of climate change on people.

Reading Strategy Make a two-column table. In the left column, write the blue and green lesson headings. In the right column, make notes that summarize the information under those headings.

Vocabulary coral bleaching

Guiding Question: What are the effects of climate change?

FOCUS Have each student think about what some of the effects of climate change might be. Then, give students five minutes to write a short paragraph summarizing their thoughts. Have pairs of students share their paragraphs with each other. At the conclusion of the les-son, ask students how they would change their paragraphs based on what they have learned.

GUIDING QUESTION

16.3 LESSON PLAN PREVIEWDifferentiated instruction Support less proficient read-ers by making a class cluster diagram to organize lesson concepts. inquiry Students investigate the effects of Hurricane Katrina.Real World Students respond to the idea that people living far from an ocean do not have to worry about sea levels rising.

16.3 RESOURCESLesson 16.3 Worksheets • Lesson 16.3 Assessment • Chapter 16 Overview Presentation

Find OutMore

Find OutMore

498 Lesson 3

Changing Migration Times Many species of birds migrate every year in the fall and spring. In the fall, they travel to places where the weather will be warmer and food will be more plentiful. Then in the spring, they fly back to their summer habitat. Some birds are now starting their spring migration earlier than before. Scientists infer that this change in migration is happening because the birds’ winter habitat becomes warmer earlier than before. This change in temperature probably sends a signal to the birds to start their migration earlier.

A change in migration time can cause problems for some birds. For example, in the spring, robins arrive on a mountaintop in Colorado about two weeks earlier than they did in the 1970s. However, climate change has caused increased snowfall on the mountain. So when the robins get there, snow still covers the ground. The robins cannot feed until the snow melts.

Problems Obtaining Food Migrating birds are not the only animals whose food supply is threatened by global warming. During the last few decades, temperature changes have been greatest in the Arctic. Ice sheets are melting and sea ice is thinning. Ice-free areas are increasing in the Arctic seas. As sea ice melts earlier and freezes later, it has become more difficult for polar bears to hunt the seals they feed on. Some polar bears have been dying of exhaustion and starvation as they try to swim long distances between ice sheets. Because the number of polar bears is declin-ing, in 2008 the polar bear was listed as a threatened species under the Endangered Species Act.

Effects of a Changing Ocean The ocean is becoming warmer. In addition, its chemistry is changing because it is absorbing more and more carbon dioxide. Both these processes have begun to affect organisms in the sea, such as corals. Corals are tiny animals that use chemicals dissolved in water to build hard, stony coverings around themselves. When the animals die, the hard coverings remain. Over time, the stony coverings of millions of corals form the massive ocean structures called coral reefs.

ReadingCheckpoint

How is the increase in atmospheric temperature affecting the migration of some bird species?

Are migrating birds in your area arriving earlier in the spring than they did formerly? Contact a state or local chapter of the National Audubon Society or other wildlife organization to find out. Ask for information on how to observe and identify birds.

FIGURE 12 Trouble Finding Food As polar bears hunt, they swim from one ice sheet to another. The space between ice sheets is increasing, and the polar bears must swim longer distances than before.

ANSWERS

Find Out More Answers will vary. Responses should indicate that students have researched migrating birds in your area.Reading Checkpoint Some spe-cies are starting the spring migration earlier than previously.

Global Climate Change 499

Coral reefs provide rich and varied habitats for many marine animals, such as sponges, worms, crabs, and fishes. Many fishes eaten by people, such as flounder, are part of coral-reef food chains. Coral reefs protect beaches against waves and support the tourist industry. Today, coral reefs are dying worldwide, and this loss will affect both ocean biodiversity and the lives of people. There are many causes of coral-reef destruction. Global climate change is one probable cause.

▶ Warmer Water Temperature Reef-building corals contain microorganisms called algae within their tissues. During pho-tosynthesis, the algae produce nutrients that supply energy, and the corals use some of the nutrients. Without these algae, corals cannot survive. However, in many places, the algae in corals are dying—a process called coral bleaching, because without the algae, the corals lose their bright colors. Scientists do not fully understand why coral bleaching is happening, but evidence indicates that the problem is often related to unusually warm water temperatures.

▶ Ocean Acidity Seawater absorbs much carbon dioxide from the atmosphere. As atmospheric carbon dioxide has increased, the amount of carbon dioxide dissolved in the ocean has increased, too. When carbon dioxide dissolves in water, it forms carbonic acid, whose formula is H2CO3. The equation for this reaction is shown below.

H2O + CO2 → H2CO3

Over time, the addition of carbonic acid to ocean water has made the water slightly more acidic. Recall that the acidity of a solution is expressed as its pH. The higher the acidity, the lower the pH. The pH of ocean water is slowly going down, and it will probably continue to do so as long as the ocean keeps absorbing more carbon dioxide. The increased acidity of ocean water may already be harming organisms that live in the ocean, including corals. Ocean acidity limits the ability of corals and other shell-building organisms to build their hard, protective coverings.

The Future of Ecosystems The future effects of climate change on ecosystems will be complex and are hard to predict. For example, an increase in atmospheric carbon dioxide may increase vegetation, since plants use carbon dioxide in photosyn-thesis. However, if drought and forest fires increase, plant life will be harmed and plants may decrease in number.

Changes will probably continue in the migration patterns of some animals and in the ranges in which specific species can survive. Because they cannot survive in the changed environ-ment, some species may become extinct. Extinction of species will decrease biodiversity.

FIGURE 13 Coral Bleaching (a) The color of healthy brain coral comes from algae. (b) When the algae die, coral bleaching occurs.

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Source: U.S. Government Accountability Office [data]; assembled by Evan Mills, Lawrence Berkeley National Laboratory.

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Impact on People Right Now Global climate change is affecting aspects of human life such as

farming, forestry, the economy, and health.

Extreme weather events, such as severe droughts and heat waves, are becoming more severe in some areas, and this increase may be linked to climate change. People are feeling the impact of bad weather and other problems associated with climate change. These effects will continue into the future.

Agriculture and Forestry The effects of climate change on agricul-ture have been complex. Some crops, such as melons and sweet potatoes, do well in heat and have probably benefited from longer growing seasons. Other crops, such as spinach and broccoli, are more suited to cooler con-ditions. In many areas, droughts have reduced crop yields. The forestry industry has also been damaged by extensive forest fires that result in part from longer, warmer, drier fire seasons. Also, forest managers are increas-ingly battling insect and disease outbreaks.

Economic Effects When yields from agriculture and forestry decrease, people who work in those industries have a hard time earning a living. Huge storms, such as Hurricane Katrina in 2005, cause enormous

damage, and this damage has economic conse-quences, too. Businesses that cater to tourists, such as shops and restaurants, had to shut down because of Katrina and therefore lost money they might have earned. Homeowners, taxpayers, and utility custom-ers had to pay to have damaged homes, highways, and power lines repaired.

The financial consequence of storms is indicated by the amount of money that insurance companies pay to people and companies that have insured their property against weather-related damage. The graph in Figure 14 shows how money paid by private and government insurers increased between 1980 and 2004. Rising insurance payments may indirectly indicate that storms are increasing in severity.

Health Effects As atmospheric temperatures have risen, the probability of severe heat waves has increased. Extreme heat can cause illnesses such as heat exhaustion and heat stroke. Heat stroke is a condition in which the body cannot control its tem-perature, and body temperature rapidly rises. Heat stroke can cause death if it is not treated quickly. A 1995 heat wave killed at least 465 people in Chicago. In 2003, another severe heat wave in Europe killed about 35,000 people.

FIGURE 14 Weather-Related Insurance Claims The graph shows that between 1980 and 2004, insurance claims for damage caused by weather have increased.

500 Lesson 3

What are the causes and conse-quences of a warming Earth?Application Have students assume the role of reporters from 50 years in the future. Have each student pre-pare a newscast describing a specific event or incident that has occurred due to global warming. For example, students’ newscasts could describe a heat wave, a drought, or the flood-ing of an island nation. Have each student share his or her newscast with the class.

BIG QUESTION

Global Climate Change 501

31. Relate Cause and Effect Explain two ways in

which global climate change is threatening corals.2. Apply Concepts What are two ways in which

climate change is affecting the way in which people earn their living?

3. Predict What might happen to coastal tourist industries if sea levels continue to rise?

4. Explore the BIGQUESTION Every year, melting water from glaciers helps fill some reservoirs that people use for water. If melting water is the source of the reservoirs’ water, why is the glacial melt-ing caused by climate change a threat to water supplies?

Future Impact on People

Computer modeling predicts that global climate change will continue to affect people.

Computer modeling has enabled scientists to make predictions about climate change. The IPCC report indicates that carbon dioxide in the atmosphere will continue to rise, and so will the temperatures of the atmosphere and ocean. These trends will affect the way people live.

Diseases The ranges of animals that transmit diseases may expand as parts of the world become warmer. Lyme disease, for example, is trans-mitted to humans by tick bites. In Canada, Lyme disease is now confined to the southern part of the country. If northern Canada becomes warmer, the ticks that carry Lyme disease will be able to survive there, and the disease may spread northward.

Sea Level As the oceans become warmer and polar ice keeps melting, sea level will continue to rise. People in the Maldives and other coastal areas worldwide are concerned about what will happen eventually. In the United States, 53 percent of the population lives in coastal areas. Many people may need to find new places to live.

Water Supply Rising sea levels increase the possibility that salt water from the ocean will intrude into freshwater aquifers and contaminate people’s freshwater supplies. The disappearance of glaciers also threatens water supplies. When glaciers release meltwater slowly, year after year, the meltwater feeds rivers and reservoirs. Therefore, glaciers now indirectly supply many people with water. If glaciers melt too quickly and eventu-ally disappear, this water supply will no longer exist. In addition, dams on many rivers and reservoirs generate electricity. If the amount of water in those rivers and reservoirs decreases significantly, people would need to obtain electricity some other way.

FIGURE 15 Effect on a Lake A dam on Diablo Lake generates electricity for Seattle, Washington. The lake is fed by many glaciers. If the glaciers melt entirely, the lake may disappear, threatening Seattle’s supply of electricity.

ANSWERS

Lesson 3 Assessment

1. Warmer ocean water contributes to coral bleaching; increasing ocean acidity interferes with the ability of corals to build their hard, protective coverings.

2. Sample answer: Droughts reduce crop yields; increased forest fires harm the forestry industry.

3. Sample answer: Beaches, which attract tourists, may disappear.

4. The melting process that fills res-ervoirs has been gradual. Climate change has sped up the melting of glaciers. Eventually, the glaciers may disappear and will no longer be a source of water.