Climate Change Lecture Notes

Transcription

1 Climate Change Lecture Notes (Topic 12A) page 1 Climate Change Lecture Notes Learning Outcomes for the Climate Change Unit 1. Students can list observations which suggest that the world is warming, and explain how or why the evidence indicates that the world is warming. 2. Students can describe how visible and infrared electromagnetic waves interact with the atmosphere and the surface of the Earth, and explain how this warms the planet (i.e., explain the greenhouse effect). 3. Students can identify the major ways in which human actions are affecting the average temperature of the Earth, and how and why they affect the temperature of the Earth. 4. Students can describe how the ocean redistributes heat between the Equator and the Poles. 5. Students can identify the major ways in which the ocean affects the average temperature of the Earth, and explain how and why the ocean affects the average temperature of the Earth. 6. Students can describe and explain how and why the amount of clouds in the atmosphere affects the average temperature of the Earth. 7. Students can describe the major ways in which the warming of the Earth s oceans and the increased levels of carbon dioxide in the ocean will affect ocean life and humans, and explain why the changes in the temperature and chemical composition of ocean water will have these impacts. 8. Students can describe the thermohaline circulation (THC) and what causes the THC, and explain how and why the THC affects the overall temperature of the Earth and the climate at the Poles. 9. Students can describe how ocean life permanently removes carbon dioxide from the ocean and atmosphere, and discuss how changes to the ocean environment would affect the rate at which life removes carbon dioxide and the implications for the overall temperature of the Earth.

2 Climate Change Lecture Notes (Topic 12A) page 2 Climate vs. Weather In this class we focus on climate, not weather. Climate is the long-term average of weather conditions (what the weather is usually like). For example, Southern California has a warm, dry climate. This does not mean that it is always warm (we have our cooler days) or that it does not rain in Southern California; it means that our weather is warm most of the time and that rain is less common here than elsewhere. Another way to think about it: weather is what conditions are like a particular day, climate is what conditions are typically like over a season or a year. Which of the following are examples of climate? Which are example of weather? During January through March of 2013, California received only 26% of normal amount of rain that in usually gets during these months. The highest temperature recorded in Los Angeles County was 80 o F yesterday. In March of 2012, nearly 80% of places where temperature measurements are regularly recorded in the United States were much warmer than normal (far above average) for March. This afternoon there is less than a 10% chance of rain.

3 Climate Change Lecture Notes (Topic 12A) page 3 Electromagnetic Waves ( EM waves ) Electromagnetic waves are disturbances (ripples, wiggles) in the electromagentic fields surrounding electrically-charged particles like electrons and protons. Electromagnetic waves are named for the size of the disturbance ( wiggle ). Fast-wiggling, small disturbances are called high frequency, short-wavelength EM waves, and slow-wiggling, large disturbances are called low frequency, long-wavelength EM waves. The collection of all of the different kinds of electromagnetic waves is called the electromagnetic spectrum. 273 K Examine the chart above. Notice the arrow pointing the wavelength row. Give examples of short-wavelength EM waves: Give examples of long-wavelength EM waves: Each kind of atom and molecule emits ( sends away ), reflects, and absorbs certain specific kinds of electromagnetic waves, because each kind of atom and molecule has its own unique number and arrangement of electrons and protons. If an atom or molecule cannot emit, reflect, or absorb a certain kind of electromagnetic wave, then these waves go through these atoms and molecules! In other words, these atoms and molecules are transparent to this kind of electromagentic wave. Think about your own observations and experiences as you answer the next 3 questions: Visible light cannot go through most substances. What substance(s) can visible light go through? What substances can X-rays go through? What substances absorb and thus block X-rays? Courtesy of NASA

4 Climate Change Lecture Notes (Topic 12A) page 4 You cannot see all kinds of electromagnetic waves (EM waves) because the rods and cones in your eyes are tuned so that they only send a signal to your brain when they pick up certain specific kinds of EM waves: visible light (red, orange, yellow, green, blue, violet). Even if you cannot see EM waves, they can still affect you: the atoms and molecules of your body can absorb them. Electromagnetic waves are created when electric objects like atoms and molecules move (e.g., wiggle). Since the atoms and molecules of objects are always moving, objects are constantly emitting (sending away) energy in the form of EM waves. Of course, the warmer an object is, the more energy it can and does emit. A temperature of 273 K is about 0 o C, the freezing point of water. Refer to the chart on the previous page. What kind of light does an object emit if it has a temperature of 0 o C? When it is dark, you cannot see most objects because there is no visible light reflecting off them and into your eyes. If an object emits visible light, on the other hand, you can see it in the dark because it creates visible light. Consider your own experience: Does room-temperature wood emit visible light? Does burning wood emit visible light? Wood typically burns at a temperture of about 232 o C. Based on this information and your answers to the questions above, why don t most ordinary objects (like those in the room around you right now) emit visible light? How could you get the objects in the room around you to emit visible light? What kind of EM waves do most objects in the room around you right now emit? If an object absorbs EM waves, the object will get (A). If an object emits (sends away) EM waves, the object will get (A). Hot objects emit (B) EM waves ( heat ) than cold objects. Very hot objects can emit (C) EM waves, but objects at room temperature or colder emit (C) EM waves. Very cold objects (D) emit EM waves ( heat ). A: warmer, colder B: more, fewer C: visible light, infrared D: do, do not

5 Climate Change Lecture Notes (Topic 12A) page 5 Greenhouses What is a greenhouse? Why is it called a green house? What happens to visible light when it hits glass? What happens to infrared light when it hits glass? Windshield Car Seat What happens to the heat emitted as infrared light by the car seat? Where is the car seat receiving heat from? In other words, what kinds of EM waves are hitting it and what are emitting them? The car seat is warmer because it is surrounded by windows. Why would the car seat be cooler if there were no windows?

6 ACTIVITY: Greenhouse Gases and the Greenhouse Effect Greenhouse gases only absorb infrared light; other kinds of light pass through them. Explain how the greenhouse effect works by filling in the spaces below. The Sun emits mainly (A) light which (B) the nitrogen and oxygen in the atmosphere and (B) Climate Change Lecture Notes (Topic 12A) page 6 the greenhouse gases in the atmosphere like. The sunlight (B) the surface of the Earth, making the surface of the Earth warmer, both the land and the ocean. The warmer they get, the more heat the land and ocean send away as (A) light. This light (B) the nitrogen and oxygen in the atmosphere but (B) the greenhouse gases in the atmosphere, making the greenhouse gases warmer and thus warming the atmosphere. The warmer the atmosphere gets, the more heat the atmosphere sends away as (A) light. About half is sent out into space, and about half is sent back to the surface of the Earth, making the Earth warmer. Possible Answers A: x-rays, ultraviolet, visible, infrared B: goes through, is absorbed by, is reflected by The Earth is warmer because it is surrounded by greenhouse gases. Why would the Earth be cooler if there were no greenhouse gases in the atomsphere? If there were no greenhouse gases in the atmosphere, what would the Earth be like? visible Atmosphere CHECK YOUR ANSWERS WITH YOUR INSTRUCTOR

7 Climate Change Lecture Notes (Topic 12A) page 7 Global Warming Aside from direct temperature measurements, what other observational evidence is there that the world has been and is getting warmer? How or why do these observations suggest that the world is getting warmer? In each case, explain your reasoning. Glaciers and Ice at the Poles: There is ice than there was in the past. This observation supports the idea that the world is getting warmer, because in a warmer world, the ice would. Sea Level: Sea level is than it was in the past. This observation supports the idea that the world is getting warmer, because in a warmer world, the ocean water would, and there would be water in the ocean since melting ice would flow into the ocean. Organisms Behavior: Plankton are blooming in the year. Warmer water makes it seem there is more sunlight (when there is not). They reproduce when there is more sunlight because they can make more food ( plankton) or find more food ( plankton). What is currently the best idea that explains why the world has warmed over the last 100 years or so? In other words, what idea is best supported by the observational evidence that we currently have? What alternative ideas are well-supported by the evidence? If an idea is well-supported by the evidence, do scientists call the idea a hypothesis or a theory? Where does a large amount of our carbon dioxide pollution go each year?

8 Climate Change Lecture Notes (Topic 12A) page 8 Why can the ocean keep absorbing more and more carbon dioxide pollution without becoming saturated? (In other words, why isn t the ocean full?) Equator South North Pole Pole Thermohaline Circulation (THC) The thermohaline circulation is a convection cell. Explain the motion of the water in the THC. The circulation is started by water sinking down from the surface of the ocean to the bottom. Water sinks at the (A) during the winter because it has a (B) density due to BOTH the temperature and salinity of the water. During the winter, the climate is very (C) at this location. When seawater freezes into ice, the salt is rejected by the ice, so seawater which does not freeze gets (D) in the winter. As the sinking water spreads across the bottom of the ocean, the water above is lifted upwards. At the surface, water moves to the (A) to replace the sinking water. A: Tropics, Mid-Latitudes, Poles C: warm, cold B: high, low D: saltier, less salty Only a small amount of water sinks to the bottom of ocean each year in certain special places where the water gets very cold and very salty. The water takes over 1000 years to go all the way around the thermohaline circulation one time. Explain how the thermohaline circulation affects the climate of the planet. The thermohaline circulation helps the ocean absorb more carbon dioxide from the atmosphere. The sinking water is filled with carbon dioxide that it absorbed from its recent contact with the atmosphere. The rising water, though, sank 1000 years ago when there was much (A) carbon dioxide in the atmosphere, so it has (B) carbon dioxide dissolved in it. Therefore, the rising water has (B) room to absorb more carbon dioxide from our modern, carbon-dioxide-rich atmosphere. This (C) the strength of the atmosphere s greenhouse effect and therefore (D) the planet. A: more, less C: increases, reduces B: lots of, very little D: warms, cools

9 Climate Change Lecture Notes (Topic 12A) page 9 The Biological Pump Ocean life helps remove carbon dioxide from the surface of the ocean and send it into the deep ocean. In other words, biology helps pump carbon dioxide down deep. Phytoplankton remove carbon dioxide from ocean water so that they can make food for themselves in a process called. CO 2 They also use carbon to make shells. For example, O 2 carbonate shells require lots of carbon. Thus, phytoplankton (A) the amount of carbon dioxide in ocean water, which allows the ocean to absorb more carbon dioxide from the atmosphere. This (B) the atmosphere s greenhouse effect and therefore (C) the planet. Bodies Sink 99% Dissolved, Decomposed, Eaten CO 2 CO 2 O 2 CO 2 1% Become Sediments However, most of the carbon absorbed by CCD phytoplankton ends up back in the water when the dead remains of ocean life, fecal matter, and other forms of organic matter are dissolved by or decomposed by. When organic matter is dissolved or decomposed, the carbon in it is released back into the ocean water. This keeps the ocean water full of carbon dioxide and therefore the ocean (D) absorb more carbon dioxide from the atmosphere. About % of the dead and decaying material does not get dissolved or decomposed before reaching the bottom and becomes sediments on the ocean floor. In other words, % of the carbon dioxide absorbed by phytoplankton eventually goes back into ocean water and thus does NOT help reduce our carbon dioxide pollution. The sediments are mainly composed of (E). The small amount of carbon in these sediments is never released back into ocean water and is ocean life s contribution to reducing our carbon dioxide pollution. A: increase, reduce D: can, cannot B: increases, reduces E: fecal matter, food molecules, mucus, shells C: warms, cools

10 The Earth s Climate: Important Influences Sunlight Climate Change Lecture Notes (Topic 12A) page 10 The amount of sunlight and where it falls changes due to variations in the Earth s orbit and tilt ( Milankovitch cycles ). Plate Tectonics Creates Volcanoes Warm the planet over the long term: come out of volcanoes. They are. Cool the planet over the short term: comes out of volcanoes. It blocks. Changes Wind & Rainfall Patterns: Mountains rise and block winds. Land and ocean have different temperatures due to their different heat capacities so as continents move, winds shift and blow in different directions. Changes in Ocean Circulation (including the thermohaline circulation) Changes in amount of sunlight reflected and absorbed: continents move: in some positions, ice and snow can build up

11 Climate Change Lecture Notes (Topic 12A) page 11 The Ocean & the Climate of the Earth Ocean Currents Sketch the gyres in the Pacific Ocean into the map on the right. 60 o N Asia 30 o N 90 o N North Pole Americas Label the boundary currents as warm or cold. The boundary currents Austrailia the Equator 30 o S and the Poles. 60 o S Possible Answers: warm, cool Thermohaline Circulation 0 o 90 o S Equator South Pole How does the thermohaline circulation affect the overall climate of the world? Explain why it has these effects. Heat Capacity % of the Earth is covered by the water in the ocean, and water has a (A) heat capacity. This means that during periods of global warming when the Earth is gaining heat the ocean warms (B) than the land, so the ocean makes the Earth warm more (C) than it otherwise would. It also means that during periods of global cooling when the Earth is losing heat the ocean cools (B) than the land, so the ocean makes the Earth cool more (C) than it otherwise would. A: high, low B: faster, slower C: quickly, slowly

12 Climate Change Lecture Notes (Topic 12A) page 12 The Atmosphere Greenhouse Gases Greenhouse gases like absorb light from the, causing them to warm up and preventing the light s energy from escaping into space. Clouds Clouds reflect (A) light from the Sun, sending back into space. This (B) the surface of the Earth by preventing it from being warmed by sunlight in the first place. Cloud Cloud Clouds absorb (A) light from the Earth. As a result, the clouds (B), and begin to send more (A) light back to the surface of the Earth. This (B) the surface of the Earth. Dust A: infrared, visible, ultraviolet B: warm(s), cool(s) Dust absorbs or reflects sunlight, preventing it from reaching the surface of the Earth. Thus, dust the surface of the Earth. The ocean affects the amount of greenhouse gases, clouds, and dust in the atmosphere. How does the ocean affect the amount of each one? Greenhouse Gases Clouds Dust

13 Climate Change Lecture Notes (Topic 12A) page 13 Climate Change and Ocean Life Consider what you have learned about how the temperature of ocean water affects the amount of life in the ocean. How and why will global warming the warming of the ocean affect the amount of life in the ocean? In other words, will there be more life in the ocean or less? Which organisms will benefit? Which organisms will suffer? How? Why? As the world warms, there will be (A) phytoplankton in the ocean, because it is (B) for them to survive in warm water. Phytoplankton need and for. It is (B) for phytoplankton to obtain sunlight if the surface water is warm, because it is (B) for them to float. It is (B) for phytoplankton to obtain nutrients if the surface water is warm, because it is (B) for (C) to bring up nutrients from the thermocline below. As the world warms, there will be (A) fish in the ocean, because. A: more, fewer B: easier, harder C: waves, upwelling If global warming reduces the amount of life in the ocean, will reduction in the amount of life help warm the Earth or will it help cool the Earth? Why? Fewer phytoplankton in the ocean will lead to a Earth. Phytoplankton absorb from ocean water, which allows the ocean to absorb more from the atmosphere. It is a gas, so if it stays in the atmosphere, it helps the Earth. How and why will extra carbon dioxide in ocean water affect the amount of life in the ocean? Which organisms will benefit? Which will suffer? How? Why? There will be life in the ocean. When carbon dioxide enters ocean water, it the ph, making the water more and thus dissolves shells made of. These algae and animals will grow more slowly and be more vulnerable to predators, so the animals who eat them will have less to eat.

14 Climate Change Lecture Notes (Topic 12A) page 14 Past Changes in Climate Earth s Climate has been unusually stable for the last 10,000 years. Changes in temperature have been small (1-2 o C, 2-4 o F), but the small variations during the Medieval Warm Period and the Little Ice Age had significant effects. Give an example of a well-known, small change in climate due to changes in the ocean that has a significant impact on California s economy. Natural, large climate changes can happen quickly (over decades) because of changes in winds and ocean currents.

15 Climate Change Lecture Notes (Topic 12A) page 15 An Example of Global Warming leading to a change in Ocean Currents and the Effect on the Climate of Europe Why did the thermohaline circulation shut down about 12,500 years ago? The thermohaline circulation is caused by (A) and (B) water sinking at the Poles. Surface water moves towards the Poles to the water which sank. Ice Sheets 16,000 years ago Mississippi River (B) water from melting glaciers on land went into the North Atlantic, so the water stopped sinking because its density was too (C). Did the shutdown of the THC circulation warm or cool Europe? Why? The shutdown of the THC (D) the climate of Europe, because (A) surface water stopped coming north. Ice Sheets 12,500 years ago St Lawrence River Why did the thermohaline circulation eventually start again? As the climate cooled, seawater began to freeze into ice, which made the water (B) again and thus its density (C) enough to sink again. Equator North Pole Did the thermohaline circulation starting again warm or cool Europe? Why? The climate (D), because (A) started coming north again to replace the sinking water. A: warm, cold B: fresh, salty C: high, low D: warmed, cooled

16 Is Global Warming Bad? Why or Why not? People who live near the Poles Climate Change Lecture Notes (Topic 12A) page 16 People who live near the Equator People who live near the Coast Shipping & Mining Resources in the Arctic Will it really be Global Warming? If the Earth s climate continues to warm, the ice sheets on Greenland will melt, and the thermohaline circulation could shut down. Why? Greenland Ice Sheet Will this cause Europe to get warmer or colder? Why? Explain your reasoning.

17 Climate Change Lecture Notes (Topic 12A) page 17 Climate Change Review Quiz 1. What kind of light do not-very-hot objects emit? a. X-rays b. Ultraviolet c. Visible d. Infrared 2. Greenhouse gases like carbon dioxide absorb visible light. a. True b. False 3. Does the thermohaline circulation warm or cool the world overall? What is the primary way that the thermohaline circulation affects the overall climate of the Earth? a. Warms: warms the surface of the ocean b. Warms: increases the greenhouse effect c. Cools: cools the surface of the ocean d. Cools: reduces the greenhouse effect e. No Overall Effect: warm and cold water just switch places How or why does the motion of the water in the thermohaline circulation produce these effects? Why does the water rising upwards in the thermohaline circulation have such low levels of carbon dioxide?

18 Climate Change Lecture Notes (Topic 12A) page Phytoplankton help clean up our pollution by absorbing carbon dioxide, and using it for a purpose which makes it less likely for the carbon dioxide to end up back in the ocean and/or atmosphere where it can cause harm. Which use makes it most likely that the carbon dioxide will be permanently removed from the environment and no longer able to cause harm? a. Breathing c. Dissolving e. Respiration b. Decomposing d. Photosynthesis f. Shells Where does the carbon go? Where is the carbon permanently stored? Which of the following add carbon dioxide to ocean water and prevent the ocean from absorbing more from the atmosphere? a. dead bodies and wastes condensing into marine snow b. decomposing of dead bodies and wastes by bacteria c. dissolving of dead bodies and wastes by ocean water d. photosynthesis by phytoplankton e. precipitation of dead bodies and wastes into sediments 5. How do clouds affect the Earth s climate? a. Warm the Earth c. Warm the Earth in some ways, and cool the Earth in other ways b. Cool the Earth d. Clouds do not have a significant impact on the temp. of the Earth Explain. 6. Aside from releasing greenhouse gases by burning fossil fuels and forests, how do humans have a major impact on the Earth s climate? a. Adding Dust ( Aerosols ) to the Air c. Filling in Wetlands b. Breathing d. Ocean Pollution Kills Phytoplankton