1. The Carbon Cycle & Changes in Atmospheric Carbon Dioxide IB Biology – Topic 5.2

2. Carbon  Crucial element to living organisms  The term organic implies that carbon must be present Life on Earth is referred to as carbon-based life  Where is carbon found? Carbohydrates, lipids, proteins, vitamins In the atmosphere (CO 2 ) Lithosphere (rocks)  Carbonates, fossil fuel  Petroleum Gasoline, kerosene, plastics

3. Carbon is constantly recycled  Photosynthesis Plants take CO 2 in These producers are eaten by consumers, which use the carbon In their bodies  Cellular respiration All trophic levels & decomposers produce CO 2 which is released back into the atmosphere  Even plants

4. Other sources of carbon dioxide  Humans! Burning wood or non-renewable resources  Petroleum products  Volcanic activity  Marine organisms can take carbon out of the water to make their shells Shells accumulate as sediments at the bottom of the ocean Trap carbon for millions of years in limestone Limestone is one of the main ingredients for cement Making cement  carbon is released as CO 2

5. The Carbon Cycle

6. Changes …  Ever since the industrial revolution (1800s), humans have produced increasing quantities of carbon dioxide Machines Factories Transportation Deforestation Burning wood (cooking, heating)  It all comes down to burning fossil fuels (coal and oil)

7. Rising CO 2 levels  Over the decades, human pollution has produced enough CO2 to raise its percentage in the atmosphere  Some suggest levels have increased by about 25% compared to pre- industrial revolution levels NASA data on CO 2 levels

8. Why do CO 2 levels fluctuate?  Plants, phytoplankton, and photosynthetic bacteria are more active in the summer months Think about Chicago in the winter … do you see a lot of green?  Therefore, more CO 2 is taken out of the atmosphere during the summer months  According to NASA data (previous slide), there has been a 19.4 % increase in the mean annual concentration of CO 2 over the past 47 years.