1. 5.2: The Greenhouse Effect 5.3 Populations

2. Carbon Cycle Show how carbon is recycled throughout the environment Show transformation of carbon from organic forms and inorganic forms Includes: Photosynthesis - removes carbon from atmosphere Cellular respiration Combustion - adds carbon to atmosphere Fossilization

4. Analyzing Changes in Atmospheric CO 2 Average CO2 concentration has increased from ~315 ppm to ~380 ppm in a span of just over 40 years. Fluctuations within the year are due to seasons. When trees lose their leaves, they will not be able to remove CO2 from the environment

5. Relationship between greenhouse gases and the Enhanced Greenhouse Effect

6. The above graph show that global temperatures have been rising Shows a correlation between rise in carbon dioxide levels and temperature rise. But is this causation?

7. Ice samples taken from Antarctica contain small pockets of air, that can be analyzed for composition. The deeper the ice sample, the “older” it is

8. The Greenhouse Effect Of all the light energy that reaches the Earth from the Sun, ~30% is reflected back into space and ~70% will warm up the Earth’s surface and eventually radiate out as infra red radiation. The Greenhouse Effect is the concept that some of this infra red radiation will become trapped in the Earth’s atmosphere by (greenhouse) gases, thus warming the Earth

9. The trapping of this energy is essential to life on Earth – it makes Earth habitable planet with temperatures suitable for sustaining life. These naturally occurring greenhouse gases have been around for a long time, but with an increase in industry, population, and land development, the level of these greenhouse gases has been increasing

10. Greenhouse Gases Carbon Dioxide CO2 Methane CH4 (contributes 20x more than CO2 ) Nitrogen oxides NOx These gases absorb the long wavelengths of infra red light, keeping them in the Earth’s atmosphere longer. This causes a Global Warming

12. Consequences of Global Warming on Arctic Ecosystems Melting of the Polar Ice Caps as the ice caps melt, they add fresh water to the ocean’s salt water  Thus, they alter the salinity. This can disrupt ecosystems This can alter ocean currents, which can alter wind currents, which can alter climate and result is drastic climate change  Increase the volume of water in the ocean This can cause severe flooding in coastal cities

14. Consequences of Global Warming on Arctic Ecosystems The white snow and ice in the Arctic reflect a lot of the Sun’s radiation. When the snow and ice melt (bc of global warming), the Artic will warm up even faster (bc light will be absorbed rather than reflected) Melting of the permafrost in Siberia would release methane gas (a greenhouse gas) thus making the planet even warmer Positive Feedback!

15. Consequences of Global Warming on Arctic Ecosystems The warmed Arctic climate causes a change in the Arctic habitat, thus changing the migration and feeding patterns of various species Includes: polar bears, seas, caribou Native Americans who hunt these animals would find it difficult due to changing migration patterns Some villages have had to relocate because of swampy conditions created with the warming

16. Consequences of Global Warming on Arctic Ecosystems Effects on Polar Bears? High temperatures melt the snow in polar bear dens, shortening their hibernation periods. Lack of ice mass mean polar bears have to swim longer distances and expend more energy to reach prey or travel. Polar bears drowning???

17. Consequences of Global Warming on Arctic Ecosystems The plant species that live and prosper in the Arctic are adapted to the environment Milder climates mean that more species would be able to survive in the Artic – increases competition. Native species can become vulnerable and possibly at risk because of this competition

18. Consequences of Global Warming on Arctic Ecosystems POSITIVES? More plant species means higher biodiversity More food for Arctic herbivores There are a lot of gas reserves in the Arctic that remain largely inaccessible. The melting of the ice would allow us to tap into this resource for oil and gas However, would that lead to positive feedback?

19. Precautionary Principle If we are not sure what the consequences of a change in our behaviour would be, then the people who want this change should prove that it will not be harmful. Ex: If you want to introduce a new medicine in the market, you must first prove that it is safe and doesn’t cause harm

20. In some cases, the people resisting change must prove that the change will cause harm This can be difficult

21. Criticisms to the Precautionary Principle Includes assumptions of consequences that have not been proven The principle is more concerned with the degree of the seriousness of the consequences and not the actual chance of them occurring Sometimes only applied to new technology and not the technology it would replace. (ex wind turbines) Used to scare people

22. Precautionary Principle and The Greenhouse Effect Since we’re not sure what the exact effects of increasing CO2 levels are, the precautionary principle can be applied Countries could agree to reduce greenhouse emissions and boycott trade with countries that do not comply This can be problematic for poorer countries. It may not be possible to reduce greenhouse emission without delaying economic growth. Can lead to increased hunger and premature death in these countries

23. Populations Factors that affect a population Natality (birth rate) Mortality (death rate) Immigration (moving in) Emigration (moving out)

24. Limiting Factors Any population has the potential to increase its numbers quickly. In most natural situations, this increase in numbers is controlled by limiting factors

25. Limiting Factors Animal Population Food availability Presence of a parasite/disease Amount of predation Available nesting sites Plant Population Amount of sunlight Amount of water Amount of carbon dioxide Temperature

26. Sigmoid Growth Curve Exponential Growth Phase - Unlimited growth due to lack of limiting factors Transitional Phase -Limiting factors start influencing the rate of increase in the population -Population still increasing, but not exponentially Plateau Phase -Population no longer increases due to limiting factors -Natality + Immigration = Mortality + Emigration -Population has reached its carrying capacity (the max number of individuals that can be supported by the environment) Carrying Capacity