1. Physics of Planetary Climate Cors221: Physics in Everyday Life Fall 2010 Module 3 Lecture 10: Mitigation

2. From Last Time For a wide range of carbon dioxide emission scenarios, global average temperatures are predicted to rise 2-4 o C (4-7 o F) by 2100. Be careful with these global average temperature numbers. This higher average is driven primarily by higher nighttime low temperatures and higher polar temperatures. Warming can also cause nonlinear effects, like changes in air and ocean circulation that can have large climate effects over subcontinent-scale regions. Warming can also lead to changes in rainfall patterns, like increased or decreased rainfall, fewer but more intense storms, and more big hurricanes. Ecosystems will shift, some will vanish, some new ones created. This would cause some extinctions. Particularly worrisome is the prospect for reduced agricultural output as optimal growing zones move, change size, and/or disappear. Melting of land ice and heating of oceans will cause sea level rise.

3. Some Costs of Doing Nothing River runoff from glacial melting in the California Sierra

4. Some Costs of Doing Nothing

5. Where Carbon Dioxide Emissions Come From

6. One Option: Reduce Emissions

7. One Option: Reduce Emissions

8. Other Advantages of Moving Away from Coal

9. CO 2 Emissions by Country

10. GDP by Country

11. Another CO 2 Drawdown Option: Carbon Capture & Sequestration

12. Carbon Sequestration: Where to Put it All?

13. Carbon Sequestration – is it expensive? A: yes

14. More Aggressive Schemes: “Geoengineering”

15. Geoengineering – Will This Really Work? 1.Stratospheric aerosols 2.Carbon Capture & Sequestration 3.Cloud Seeding 4.Weathering Enhancement 5.Giant Space Reflectors 6.Iron Seeding of Oceans 7.More Plants & Forests

16. Key Points Costs of doing nothing, “business as usual” are NOT ZERO. Estimated to be at least 1.8% of GDP in 2100. Carbon Dioxide emissions come from power plants, cars & planes, industrial processes (concrete), heating homes, etc. Emission reduction is possible. It will cost money, but comparable to the cost of doing nothing. However, it requires EVERYONE to AGREE – if 90% of the world cuts emissions, then the last 10% could violate the agreement, getting economic benefits while incurring only slight greenhouse penalties for all. Carbon capture & sequestration could reduce the dirtiness of fossil fuel burning and/or pull CO 2 out of the air directly. But where to put it, and how to pay for it? Geoengineering would intentionally terraform Earth to be how it was before – but would it really?