Topic 5

1. Topic 5 Carbon in the Lithosphere and Biosphere

2. Lesson 1 The Carbon Cycle

3. Introduction Carbon dioxide dominated the atmosphere of early Earth. An important step in the evolution of the atmosphere was the removal of a lot of this Carbon dioxide. Where did it go?

4. Introduction Carbon presents itself in many different forms around the Earth and is ‘locked up’ within different molecules. Carbon can take the form of: • Inorganic (not from living material) materials in rocks and minerals. • Organic materials (from once living organisms) • Gases: Carbon Dioxide CO2, Carbon Monoxide CO and Methane CH4

5. The Carbon Cycle Carbon is removed, transported and converted into many different forms which is represented in the Carbon Cycle Diagram below:

6. The Carbon Cycle Photosynthesis removes carbon dioxide from the atmosphere by converting CO2 and water into carbohydrate molecules which are trapped within the bodies of living organisms. This ultimately traps the carbon dioxide from returning to the atmosphere.

7. The Carbon Cycle This carbon trapped by plants through photosynthesis is then passed along food chains by organisms that eat these plants. When these organisms die the carbon is released back into the ground and atmosphere.

8. The Carbon Cycle When dead organic materials accumulate in swampy environments this locks up carbon and forms coal and natural gas.

9. The Carbon Cycle Carbon dioxide in the atmosphere is also dissolved in water droplets and transported to the ocean through the water cycle. Organisms in the ocean are able to convert the CO2 into carbohydrates through photosynthesis.

10. The Carbon Cycle Dissolved carbon dioxide in the ocean also reacts with other dissolved ions like calcium and magnesium. As these molecules combine they chemically precipitate as carbonate minerals and are deposited on the ocean floor. These sediments eventually turn into limestone and dolomite.

11. The Carbon Cycle Living organisms in the ocean (shellfish/coral) use carbonates dissolved in the water to form shells and other hard parts. When these organisms die the carbon trapped in their parts are deposited on ocean floors.

12. The Carbon Cycle Carbon trapped in marine sediments and rocks are stored as inorganic carbon and can remain in this form for hundreds of millions of years. Carbon stored in the bodies of terrestrial plants and animals will only remain in the bodies until the organism dies. When this happens most of the carbon is returned to the atmosphere

13. Homework Read pages 31-33 Prelim Spotlight Text Update Vocab list Complete DOT Point 4.2, 4.4, 4.5 Complete Activity 1.21 Carbon Reserves pg 31-32 Prelim Spotlight Text

14. Lesson 2 The Greenhouse Effect

15. Introduction There is approximately 700 Billion tonnes of carbon in the atmosphere. This carbon in the atmosphere is mainly in the form of CO2. This amount is on the rise because of industrial emissions.

16. The Greenhouse Effect Naturally occurring carbon dioxide and water vapour in the atmosphere contribute to the trapping of infrared radiation resulting in an increase in surface temperature. We can compare this to how a greenhouse traps radiation.

17. The Greenhouse Effect Other gases and processes also contribute to the gases in the atmosphere that traps infrared radiation: • Farmers use nitrogen based fertilisers extensively which react with oxygen to produce nitrous oxide which is then released into the atmosphere. • Gases used as solvents in aerosols, fire extinguishers and refrigerator and air-conditioning units are released into the atmosphere. • Methane produced in marshes, rice paddies and cattle • Carbon Dioxide from combustion in industry and transport

18. The Greenhouse Effect Since the start of the industrial revolution in the 1800’s the concentration of CO2 in the atmosphere has increased considerably. The CO2 is released by the burning of fossil fuels (coal, oil, natural gas) to provide energy for industry.

19. The Greenhouse Effect Some of this CO2 is absorbed into the oceans however a large percentage stays in the atmosphere and acts as an insulator trapping infrared radiation raising the Earth’s average temperature.

20. Correlation between CO2 and Temperature Scientists have analysed past carbon dioxide concentrations and temperature fluctuations and there is an obvious correlation. There is strong evidence to link carbon dioxide fluctuations with global temperature variations.

21. Correlation between CO2 and Temperature The interrelationship between the Earth’s atmosphere, oceans and land is so complex that it is difficult to say that one factor was the sole cause. For example, we don’t fully understand the following: • How much oceans dissolve carbon dioxide • The distribution of carbon dioxide throughout the oceans and how it is circulated by currents • The effects of different clouds (some cool the Earth while others warm Earth)

22. Comparisons with Our Neighbours One argument that supports the idea that increased CO2 levels are related to increased temperatures are the observations scientists have made about Venus.

23. Comparisons with Our Neighbours Venus receives less light energy on its surface than Earth because of it’s large volume of clouds which reflect the radiation. However, it’s surface temperature is more than twice as hot as Earth’s

24. Comparisons with Our Neighbours We also know that the atmosphere of Venus has 300000 times more CO2 than Earth’s. Scientists believe this may indicate that the greenhouse effect is operating at a much greater degree.

25. Predictions For The Future Scientists have predicted that a doubling of the amount of CO2 will lead to a climactic temperature increase of 1-4 degrees Celsius due largely to the greenhouse effect. Scientists have also estimated that over the next 100 years the CO2 levels should double the levels of the 19th century.

26. Predictions For The Future There are other areas we must consider apart from temperature change when looking at increased levels of CO2 in the atmosphere. For example, the effect on photosynthetic organisms in both aquatic and terrestrial environments.

27. Predictions For The Future Experiments on plants with increased concentrations of atmospheric CO2 have shown both positive and negative effects depending on species and the amount of CO2.

28. Homework Read pages 33-34, 37-41 Prelim Spotlight Text Update vocab list Complete DOT Point 5.1 pg 29