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WHAT CAUSES CLIMATE CHANGE? Earth’s climate is a balance between how much energy is received from the Sun and how much energy leaves Earth. Climate change happens any time the balance is altered. NATURAL CAUSES OF CLIMATE CHANGE Sometimes Earth receives more energy from the Sun than usual. The Sun has active periods during which it gives off more energy than at other times. There is evidence that these periods, which occur in cycles of about 11 years, correspond to warming trends on Earth. The tilt of Earth’s axis also changes the amount of energy received from the Sun. The tilt of Earth’s axis ranges from 22° to 25° in a 41 000-year cycle. The differences in tilt could change climate conditions. Locations tilted closer to the Sun will warm. Locations tilted farther from the Sun will cool. Volcanic eruptions can throw huge amounts of dust and ash high into the atmosphere (Figure 2.22). This dust and ash can remain there for months or even years. This material reflects solar energy back into space, reducing the amount of heat entering Earth’s climate system. FIGURE 2.22 Mount Pinatubo in the Philippines erupted in 1991. The ash cloud was so large that it lowered the global average temperature for a period of one to three years. I wonder what other effects this volcanic eruption caused? 66 UNIT 1: Physical Patterns in a Changing World NEL THE GREENHOUSE EFFECT Natural events such as volcanic eruptions release huge amounts of greenhouse gases into the atmosphere. Greenhouse gases are gases that absorb energy from the Sun. Greenhouse gases include CO2, methane, and ozone. These gases have the same effect on Earth as glass does in a greenhouse. The Sun’s energy passes through the glass of the greenhouse and some of it becomes trapped inside to warm the plants. In the same way, the Sun’s energy passes through Earth’s atmosphere. The greenhouse gases prevent some of the energy from going back into space, and the trapped heat warms Earth (Figure 2.23). The greenhouse effect is an important natural process. It helps keep Earth warm enough to support life. However, if the amount of greenhouse gases increases, more of the Sun’s energy gets trapped in Earth’s system. It changes the balance between incoming and outgoing energy, and can cause climate change. The average temperatures on Earth’s surface increased by 0.8 degrees Celsius in the past 100 years. But in the past 66 years, between 1948 and 2013, the average temperature in Canada warmed by 1.6 degrees Celsius. More greenhouse gases in the atmosphere have caused the average temperature to rise. greenhouse gases gases in the atmosphere that contribute to the greenhouse effect by absorbing energy from the Sun; they include CO2, methane, and ozone Some sunlight passes through the atmosphere to warm Earth’s surface. Greenhouse gases in the atmosphere trap some of the radiated thermal energy, keeping Earth warm. Some sunlight is reflected back to space by the atmosphere. atmosphere FIGURE 2.23 The greenhouse effect traps warmer air close to Earth. Without the greenhouse effect, the average temperature on Earth would be about 33 °C colder than it is now. NEL CHAPTER 2: Changing Patterns of Climate 67 HUMAN ACTIONS CAUSING CLIMATE CHANGE 350 CO2 (parts per million) Scientists agree that global warming is related to the rising amounts of greenhouse gases in the atmosphere (Figure 2.24). Where are these extra greenhouse gases coming from? Scientists have considered both natural and human-made sources of greenhouse gases. The increase in CO2, the most common greenhouse gas, began with the widespread use of fossil fuels in the 1800s. Fossil fuels are fuels obtained from beneath Earth’s surface. Examples of fossil fuels include oil, natural gas, and coal. You will learn more about these in Chapter 8. CO2 Levels in the Atmosphere 400 300 250 200 150 100 50 0 1010 1110 1210 1310 1410 1510 1610 1710 1810 1910 2010 Years FIGURE 2.24 This line graph shows CO2 levels in the atmosphere from 1010 to 2010. HUMAN-MADE SOURCES OF GREENHOUSE GASES fossil fuels fuels, such as oil, natural gas, and coal, formed millions of years ago from the remains of plants and animals What human activities produce greenhouse gases? Most people would say energy production and transportation. But many other human activities also produce greenhouse gases (Figure 2.25). The major human activities that produce greenhouse gases include the following: What might be • Electricity production: We burn fossil fuels, such as natural gas, oil, some ways of reducing and coal, to produce electricity. our use of fossil fuels • Transportation: Most cars, trains, ships, and planes are powered by fossil for transportation? fuels, such as gasolineGeography and diesel.7 SB • Industry: Many industries, such as the steel industry, use fossil fuels to 0-17-659048-X produce heat for making products. C02-F19-G07SB FN • Homes and businesses: burned for heat. Some Crowle Art Group CO Fossil fuels are of the chemicals we use in our homes or businesses, such as the Passalso give off 3rd pass coolants in refrigerators, greenhouse gases. Approved Canada’s Greenhouse Gas Emissions, 2011 Not Approved • Agriculture: Greenhouse gases are waste produced in animals’ digestive tracts 7% and emitted into the air. They are also agriculture given off when animal waste decays. The 10% decaying of unused plant materials, such energy production as waste from food crops, also produces industry 36% greenhouse gases. 11% • Waste: Household wastes and industrial wastes release greenhouse gases as homes and they decompose. businesses 12% transportation 24% FIGURE 2.25 Energy production and transportation are major sources of greenhouse gases. However, other human activities are also a significant source of greenhouse gases. 68 UNIT 1: Physical Patterns in a Changing World NEL HEROES IN ACTION ALEC LOORZ: KIDS VS GLOBAL WARMING Alec Loorz (Figure 2.26) became a climate activist at the age of 12. Inspired by the documentary An Inconvenient Truth, Loorz wanted to contribute to a solution to global warming. He tried to join different organizations but they turned him away, saying he was too young. So Loorz started his own organization when he was 13: Kids vs Global Warming. “I used to play a lot of video games, and goof off, and get sent to the office at school,” he said. “But once I realized it was my generation that was going to be the first to really be affected by climate change, I made up my mind to do something about it.” Through his organization, Loorz has spoken all over the world to hundreds of thousands of people on the subject of global warming. Through the iMatter campaign, Kids vs Global Warming is also empowering young people to take a leadership role in addressing climate change. The goal of the campaign is to create a youth climate movement. Young people will help create awareness by educating their peers, politicians, and the general public through speeches and presentations, and through the international iMatter march. Loorz has done more than give speeches. He also sued the United States government. In 2011, Loorz, along with four other teenagers in the organization, filed a lawsuit to try to force the U.S. government to reduce the nation’s CO2 emissions. They wanted reductions of at least 6 percent per year beginning in 2013. The teens also wanted to make people across the country aware that the United States had made little progress in dealing with climate change. In an interview about the lawsuit, Loorz said, “I think a lot of young people realize that this is an urgent time, and that we’re not going to solve this problem just by riding our bikes more.” Although the lawsuit was dismissed, Kids vs Global Warming filed an appeal in 2013. They continue to seek a way to hold the government accountable for the impact of their decisions on the climate. “WE’RE NOT GOING TO SOLVE THIS PROBLEM JUST BY RIDING OUR BIKES MORE.” FIGURE 2.26 Environmental activist Alec Loorz A CALL TO ACTION 1.Think about some environmental challenges you care about. What are some ways you can contribute? 2.How can you raise awareness of global warming in your community? How would you try to reach a more global audience? NEL CHAPTER 2: Changing Patterns of Climate 69 FIGURE 2.27 Greenacre Park in New York City is an example of a pocket park. New York City was one of the first cities to create pocket parks. How could a pocket park benefit my community? Why might some people argue that climate change is unimportant or that we should not do anything about it? TAKING ACTION AGAINST CLIMATE CHANGE How should we deal with climate change? This has been debated by many scientists, governments, and concerned citizens around the world. Not everyone agrees that action should be taken. Some people feel that climate change is a natural process and there is nothing we can do. Others doubt that climate change is real, or that humans are causing it. However, most geographers and other scientists agree that human actions are a cause of climate change. As you learned earlier in the chapter, we will feel the impacts of climate change in the coming years. People need to take action now to address the effects of climate change. There are two ways we can deal with climate change: mitigation and adaptation. MITIGATION mitigation action taken to reduce the consequences of a problem 70 Mitigation means reducing the consequences of a problem. To mitigate climate change, we must act on its causes. One of the key greenhouse gases we produce is CO2. UNIT 1: Physical Patterns in a Changing World NEL By making different choices, we can reduce CO2 levels in the atmosphere. Here are some examples of actions we can take to help mitigate the problem: • switch from fossil fuels to other forms of energy such as solar or wind • drive a fuel-efficient car, ride a bike, or walk instead of driving • reduce your energy use, such as by turning off the lights when no one is in the room • preserve green spaces or plant more trees to absorb greenhouse gases • use technology to capture CO2 emitted from smokestacks • consume locally made products instead of products that come from far away • reduce, reuse, and recycle to reduce the amount of energy used to manufacture new products • conserve water by using less or using it more efficiently ADAPTATION adaptation a change or adjustment made to deal with a new situation An adaptation is a change made to deal with a new situation. In the case of climate change, we must adjust to the effects of climate change to try to protect ourselves and our planet. Some adaptations include • growing crops that will adapt and grow in the new climate • expanding healthcare to treat or prevent health problems caused by extreme weather events such as heat waves • protecting water sources from the effects of warmer temperatures and extreme weather, for example, by building larger storage places • building more parks and green spaces in cities where people can cool off Figure 2.27 shows an example of a pocket park. Pocket parks are smallscale urban parks that can be built in small spaces—in abandoned lots, in between buildings, or in former parking lots. Cities are adopting these pocket parks as a way to increase green spaces. CHECK-IN 1. INTERRELATIONSHIPS In a sentence or two, explain the differences between mitigating a problem and adapting to a problem. 2. INTERPRET AND ANALYZE Think about what you know or have learned about extreme weather. Identify two actions that people could take to mitigate the problem and two actions that would help them adapt to the problem. NEL 3. COMMUNICATE Suppose you read an ad claiming that climate change is not a big problem and so we should do nothing about it. Create an ad in reply. Be sure to provide evidence to support your opinion. CHAPTER 2: Changing Patterns of Climate 71