1. Atmosphere and Climate Change Section 3: Global Warming

2. The Greenhouse Effect The Earth is similar to a _______________. The Earth’s atmosphere acts like the glass in a _______________. Sunlight streams through the _______________and heats the Earth. As this heat radiates up from Earth’s _______________, some of it escapes into space. The rest of the heat is absorbed by gases in the _______________and warms the air. This process of heat _______________is called the _______________ ____________.

3. The Greenhouse Effect

4. Not every gas in our _______________ absorbs heat in this way. A _______________ is a gas composed of molecules that absorb and radiate _______________radiation from the sun. The major greenhouse gases are _______________, _______________, CFCs, _______________, and nitrous oxide. Of these, _______________and _______________ account for most of the absorption of that occurs in the atmosphere.

5. Measuring Carbon Dioxide in the Atmosphere In 1985, a _______________ named Charles Keeling installed an instrument at the top of a tall tower on the volcano _______________ in Hawaii. He wanted to precisely measure the amount of _______________ in the air, far away from forests and cities. In a forest, _______________ levels rise and fall with the daily rhythms of _______________. Near cities, carbon dioxide from traffic and industrial pollution raises the local concentration of gas.

6. Measuring Carbon Dioxide in the Atmosphere The winds that blow steadily over _______________ have come thousands of miles across the Pacific Ocean, far from most forests and human activities, swirling and mixing as they traveled. _______________ reasoned that at Mauna Loa, the average _______________ levels for the entire Earth could be measured.

7. Measuring Carbon Dioxide in the Atmosphere Keeling’s first measurement, in March of 1958, was __________ percent, and the levels rose slightly the next month. By summer the levels were falling, but in the winter, they rose again. During the summer, _______________ use more carbon dioxide for photosynthesis than they release in respiration, causing the levels to drop. In the winter, dying grasses and fallen leaves decay and ___________ the carbon that was stored in them, causing levels to rise.

8. Rising Carbon Dioxide Levels After a few years of _______________, it was obvious that the levels were undergoing changes other than _______________ fluctuations. Each year, the high carbon dioxide levels of winter were _______________, and each year, the summer levels did not fall as _______________. In 42 years, carbon dioxide has gone from 314 to 386 parts per million, an increase of _______________ per million. This increase may be due to the burning of ______________.

9. Rising Carbon Dioxide Levels

10. Greenhouse Gases and the Earth’s Temperature Many scientists think that because greenhouse gases trap heat near the Earth’s surface, more greenhouse gases in the atmosphere will result in an __________ in global temperature. A comparison of carbon dioxide in the _____________ and average global temperatures for the past _______ years support that view.

11. Greenhouse Gases and the Earth’s Temperature Today, we are releasing more _______________ than any other greenhouse gas into the atmosphere. Millions of tons of carbon dioxide are released into the atmosphere each year from _______________ that burn coal or oil, and cars that burn _______________. Millions of trees are _______________ in tropical rainforest to clear the land for farming. We also release other greenhouse gases, such as CFCs, _______________, and nitrous oxide, in significant amounts.

12. Greenhouse Gases

13. How Certain is Global Warming? _______________ is a gradual increase in the average global temperature that is due to a higher _______________ of gases such as _______________ in the atmosphere. Earth’s average global _______________ increased during the 20th century and many scientists predict that this _______________ trend will continue throughout the 21st century.

14. How Certain is Global Warming

15. How Certain is Global Warming? However, not all scientists agree that the observed _______________ is due to greenhouse gases. Some scientists believe that the warming is part of natural _______________ _______________. They point out that widespread _______________ in temperature have occurred throughout geological time.

16. Modeling Global Warming Scientists are currently _______________ to make accurate predictions about the _______________ of global warming because climatic patterns are too complex and too many variables must be taken into account to be solved, even using today’s fastest computers. Predictions about climate change are based on ___________ _______________ that predict how phenomena such as temperature, rainfall patterns, and _______________ will be affected.

17. Modeling Global Warming Computer modeling is complicated by the Earth’s _________ _______________ that sometimes make it necessary to use different equations under changing simulated ___________. These feedback processes are related to things such as clouds, ___________, ice, changes in ___________, and changes in ___________. Computer models are becoming more reliable as more data are available, additional factors are considered, and faster computers are built.

18. The Consequences of a Warmer Earth The ___________ of global warming could include a number of potentially serious environmental problems. These problems range from the ___________ of global weather patterns and a global rise in ___________ to adverse impacts on ___________, ___________, and animal and plant ___________. Other impacts on the ___________ that could not be predicted by computer models might also arise.

19. Melting Ice and Rising Sea Levels If the global temperature ___________, the amount of ice and snow at the poles would ___________, causing sea levels around the world to ___________. Coastal ___________, and other low-lying areas could be ___________. People who live near coastlines could lose their homes and sources of income. The ___________ of bays and estuaries might increase, adversely affecting marine fisheries. Also, ___________ aquifers could become too salty to be used as sources of fresh water.

20. Global Weather Patterns If the Earth warms up significantly, the ___________ of the oceans will absorb more heat, which may make hurricanes and ___________ more common. Some scientists are concerned that global warming will also cause a change in ocean ___________ patterns, shutting off the ___________ ___________. Such a change could significantly affect the world’s weather. Severe ___________ could occur in some regions at the same time droughts devastate other regions.

21. Human Health Problems Greater numbers of heat related ___________ could occur. Very young and very old people would have the greatest risk of heat ___________. Concentrations of ground level ___________ could increase as air temperatures rise, causing ___________ illnesses, especially in urban areas, to increase. Warmer temperatures might enable ___________, which carry diseases such as ___________ and ___________, to greatly increase in number.

22. Agriculture Agriculture would be most severely impacted by global warming if extreme weather events, such as ___________, became more frequent. Higher temperatures could result in ___________ crop ___________. As a result, the demand for ___________ could increase, which would further deplete ___________ that have already been ___________.

23. Effects on Plants Climate change could alter the ___________ of plant species and could change the ___________ of plant communities. A warmer climate could cause trees to ___________ northward into cooler areas. ___________ could shrink in areas in the southern part of their range and lose ___________.

24. Effects on animals Global warming could cause a shift in the ___________ range of some animals. For example, Northern birds may not migrate as far south during the winter. Warming of surface waters of the ocean might cause a reduction of ___________, tiny ___________ animals, that many marine animals depend on for food. Warming tropical waters may kill ___________ that nourish ___________, thus destroying coral ___________.

25. Recent Findings The _________________ on Climate Change (IPCC) issued its Third Assessment Report (TAR) in 2001 that described what was currently known about the global ____________ system and provided future ____________ about the state of the global climate ____________. The IPCC reported that the average global ____________ ____________ increased by 0.6ºC during the 20th century, snow and ice cover has ____________, and the global sea level has ____________.

26. Recent Findings The IPCC also reported that concentrations of ____________ gases have continued to increase as a result of human ____________. It has also predicted that human ____________ will continue to change the ____________ of the Earth’s atmosphere and continue to ____________ the Earth throughout the 21st century.

27. Reducing the Risk The ____________ ____________ is an international treaty according to which developed countries that signed the treaty agree to reduce their emissions of carbon dioxide and other ____________ that may contribute to global warming by the year 2012. In March of 2001, the United States decided not to ____________ the Kyoto Protocol. However, most other developed nations are going ahead with the treaty.

28. Reducing the Risk The need to slow global warming has been ____________ by the global community. Some nations and organizations have engaged in ____________ projects to reduce carbon dioxide. However, the attempt to ____________ global warming is made difficult by the ____________, ____________, and ____________ factors faced by different countries.

29. Reducing the Risk Conflict has already arisen between ____________ and ____________ countries over future CO 2 emissions. Developing countries are projected to make up ____________ of all CO 2 emissions by 2035.

30. Reducing the Risk