The document discusses sources and sinks of greenhouse gases and their contribution to climate change. It explains that the main natural greenhouse gas is water vapor, while the main human-caused one is carbon dioxide released from sources like burning fossil fuels. Forests normally act as carbon sinks by absorbing carbon dioxide through photosynthesis, but deforestation has reduced this, increasing atmospheric carbon levels. In addition to large industries, personal lifestyle choices and consumption patterns also generate significant greenhouse gas emissions through activities like waste disposal, manufacturing of disposable products, electricity use, transportation of goods, and more.

1. GHG Sources and human activities

2. Recall that the most important contributor to the natural greenhouse effect is water vapour .

3. The most important GHG contributing to the anthropogenic greenhouse effect is carbon dioxide.

4. Any process that releases carbon dioxide into the atmosphere is called a carbon source .

5. For example, burning fossil fuels and the respiration of organisms are both carbon sources . Sources and Sinks

6. Fossil fuels are materials such as coal , oil and gas that were formed underground from the remains of once-living organisms . Sources and Sinks

7. Because organisms are made up of carbon , hydrogen and oxygen , fossil fuels are called hydrocarbons . Sources and Sinks

8. While these fossil fuels are in the ground , their carbon content is undisturbed .

9. When they are extracted from the ground, they release a small amount of methane and carbon dioxide into the atmosphere.

10. When fossil fuels are burned to produce energy, large amounts of carbon dioxide and nitrous oxide are released.

11. For example, for every liter of gasoline used in a car, 2.3 kg of carbon dioxide is released into the atmosphere. Sources and Sinks

12. Sources and Sinks

13. Sources and Sinks

14. Beginning in the late 1700s , the population of North America grew rapidly.

15. European people settled in the forests and started to clear the land of trees to provide timber for fuel and to prepare land for agriculture .

16. Before the settlers arrived, over 90% of southern Ontario was covered with trees .

17. Today, only about 38% of that land is forested .

18. Deforestation Forests play an important role in removing carbon dioxide from the air through the process of photosynthesis .

19. Photosynthesis is a carbon sink , which is any process that takes carbon dioxide from the atmosphere and stores it. Deforestation

20. Deforestation in North and South America over the last two centuries has reduced Earth’s carbon sink and decreased the amount of CO 2 being removed from the atmosphere .

21. Both natural processes and human activities can affect carbon sources and sinks .

22. For example, if a forest fire is started, whether by lightning or people camping, the forest is no longer a carbon sink . Sources and Sinks

23. Instead, the burning forest releases CO 2 into the atmosphere, becoming a carbon source .

24. Human activities, such as the production of electrical energy or the use of fossil fuels , release large amounts of carbon dioxide into the atmosphere. Sources and Sinks

25. Sources and Sinks It is easy to conclude that large industries and electricity generation are a main cause of the problem, but personal lifestyle choices also contribute to greenhouse gas emissions .

26. Consider the amount of garbage generated by your household or school… Sources and Sinks

27. Garbage in a landfill requires space , and it is broken down by anaerobic bacteria . This process adds methane - a greenhouse gas - to the atmosphere.

28. As well, North Americans purchase many disposable products. Sources and Sinks

29. It takes energy to manufacture these products, and they take up space in landfill sites after being used just once .

30. North Americans consume much more than people in many other countries.

31. Also consider the amount of electricity you use at home…

32. … or the number of lights left on in office buildings at night.

33. Think about how far trucks must travel to deliver the goods we want.

34. These are just some examples of the many ways we contribute to greenhouse gas emissions and hence climate change. Sources and Sinks

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