1. Goal: To understand the climate of the earth. Objectives: 1)To understand the Greenhouse effect. 2)To compare Greenhouse effect vs the climate. 3)To learn about Carbon cycle. 4)To explore Global warming 5)To examine the possible Solutions – if any

2. Which of the following most accurately describes the greenhouse effect? A) Another term for global warming. B) The process by which heat is trapped. C) Reflection of sunlight by the atmosphere. D) Sunlight which is reflected off of the earth reflected by the atmosphere. E) Sunlight being absorbed by the atmosphere. F) Sunlight is absorbed by the earth. Earth emits IR light which is absorbed by the atmosphere then re-emitted in the IR. G) Sunlight is absorbed by the earth. Earth emits IR light which is reflected by the atmosphere. H) all of the above I) None of the above

3. The greenhouse effect The greenhouse effect starts with the sun. Some of the sun’s light gets reflected by our atmosphere. However, that actually COOLS the planet, and is therefore a separate topic. 20% of the sun’s light gets absorbed by the atmosphere, 30% is reflected by the surface out to space, and 50% goes elsewhere, but where? A) absorbed by the earth B) trapped by the earth C) trapped by the atmosphere D) none of the above

4. Greenhouse effect, part 2 What does the earth do with this energy? The earth emits this energy like a blackbody. Since the earth is 288 K on average, it emits in the infrared.

5. Greenhouse Effect part 3 Most of the IR energy emitted by the earth (80-90%) is absorbed by the atmosphere. The absorbers are gasses called Greenhouse gasses. These are gasses that absorb infrared heat, but most let optical light pass through. Note it is NOT “trapped”, and it is not “reflected”. What is the largest contributing greenhouse gas? A) Carbon Dioxide B) Nitrogen C) Oxygen D) Water Vapor

6. Greenhouse effect – part 4 Finally, the atmosphere emits its own energy. Half of this goes up, and half goes down. The half going up mostly escapes to space. The half going down is absorbed by the earth. So, while most scientists oversimplify this picture by calling the atmosphere a blanket, really it is a heat lamp.

7. http://earthobservatory.nasa.gov/Features/EnergyBalance/printall.php

8. Summer of Greenhouse effect So, the Greenhouse effect acts as a heat lamp which is powered by the earth – thus heating the earth. The greenhouse effect warms the earth by 60 F. Is the greenhouse effect a good thing or bad thing? A) good B) bad

9. Greenhouse Effect implications Without the greenhouse effect, the earth would be FROZEN! So, in moderation, the greenhouse effect is a good thing. However, over long time spans (thousands of years), levels of greenhouse gasses such as Carbon Dioxide change. This changes the climate!

10. CO2 over past 200,000 years vs climate As you can see, the climate and the CO2 levels are almost and exact match. Please note the low points every 26,000 years, which represents the ice ages. Please see how the temperature levels were dropping slowly over the last 10k years.

11. Geologic Carbon Dioxide levels

12. Why does the earth’s temperature rise and fall? There is usually an energy balance. The energy absorbed = energy emitted. Totally energy stays the same. HOWEVER, if more energy is absorbed for some reason, then there is no longer in balance. So, the earth gains energy! This means the earth gets warmer. As the earth gets warmer, it emits more energy. At some point the energy absorbed = energy emitted, and there is a new balance. So, > greenhouse effect = higher temperature (if everything else remains equal).

13. What changes the Carbon Dioxide levels? What part of the Carbon Cycle absorbs (net) the most Carbon Dioxide per year? A) plants B) animals C) atmosphere D) ocean

14. Carbon Cycle – diagram courtesy of wikipedia

15. Ledley et all 1999 Oops, CO2 levels are rising FAST! 2 ppm per year!

16. How do we know?

17. What are the possible results? Melting of Ice caps! Greenland and Antarctica could add 40 m to the ocean levels! That would flood most cities in the world! Indianapolis elevation: 240 m Warming of global temperatures by up to 5C (9 F) over next 50-100 years More severe weather. Shift in climate zones, and shifts in climate.

18. Uncertainties: None of the models agree on the specifics. There is a lot of uncertainty on how clouds play a role in the equation. Also, other chemicals BLOCK sunlight, this dampers the temperature increases – in the short term. However, they all show increased temperatures worldwide.

19. Temporary relief! It seems that the Antarctic ice mass is INCREASING – at least on the east side This could keep ocean levels steady for the next few decades but it is not currently well understood When will this trend reverse?

20. Possible Effects? It is uncertain how species will react. Some will probably not survive. Most probably will though, although it will change ours lives greatly as we basically have to move all our cities inland as ocean levels rise. Also, the change in climates will move all of the best places to farm. This will hurt India and China. Also, this will drop the sustainable human potential population from 8 billion down to possibly 2 billion.

21. http://www.printableworldmap.org/

22. Solutions? Move cities inland – evacuate Florida and Louisiana. Move farmlands to the areas that will be the new farm zones. Develop new farming technologies to increase crop yields or be able to grow crops using less water. Switch to energy sources that don’t produce greenhouse gasses (such as solar and wind), or ones that only put back what they take out such as biomass and ethanol. No matter what we do, it will take a good amount of effort, time, and lots and lots of $$$

23. How much land do you think it would take to power the entire US by wind and solar power?

24. Why don’t we? Cost would be in the tens of trillions of dollars! Would require a complete change of our system including to electric/fuel cell powered cars and hydrogen powered jets. Tradition

25. Structure of the Earth’s atmosphere

26. Conclusion The greenhouse effect is the atmosphere absorbing the infrared energy the earth emits, then reemitting it back. The greenhouse effect is useful, in moderation. The magnitude of greenhouse effect changes with time naturally – although not as quickly as we have changed it. This could cause problems for us if we care about things such as coastal cities and being able to keep our farms where they are. If we are okay with moving our cities and farms, then there is not much of a problem.