A description of the three factors that determine the average surface temperature of a rocky planet with a gaseous atmosphere that is orbiting a star (such as our Earth).

A description of how scientists have recorded the Earth’s climate history over time scales from years to millions of years.

1. An explanation of how CO2 participates in a global “thermostat” that works to regulate Earth’s temperature over timescales of hundreds of thousands to millions of years. 
2. An explanation of why we know that CO2 is a common forcing factor in Earth’s climate that is seen in

our escape from “Snowball Earth” (about 650 million years ago, mya);

1. the end-Permian Mass Extinction (251 mya); 
2. the early Cenozoic temperature U-turn (about 50 mya); 

the glacial/interglacial cycles of the last million years (about 100,000-year intervals); and

• the last 1,000 years.Is there any possibility that the CO2 forcing factor is not still operating today? Are there any viable alternative explanations for the observed warming over the last 150 years?

An explanation of why water vapor, the most abundant greenhouse gas, is not a forcing but an amplifying feedback (explain amplifying and stabilizing feedbacks, with examples).

• A description of what we know of the Earth’s climate history at three timescales, as shown in charts I, II, and III in the figure below. Indicate in your answers what happened and why: what were the causes of these changes? For the Cenozoic (the last 65 million years depicted in chart 1), say what happened and why at points A—E. DO NOT simply describe the curve; you must say what happened and why at points A—E.

An explanation of how human civilization has been affecting the CO2 forcing factor since the Industrial Revolution of the 19th century and the likely effects of this over the next 100 years. If you can, include a brief discussion of the direct and indirect effects of atmospheric aerosols on the Earth’s energy budget (i.e., “global dimming”). Also, what is the third way than humans have altered the atmosphere that almost had catastrophic impacts on life at the surface? [3 points] 

• Forward-looking: 1) Include a brief discussion saying whether planting trees could be a solution to climate change impacts from global warming (c.f., TeamTrees vs REALITY!!); 2) Include a brief discussion of the methods that might be used to “geoengineer” Earth’s climate, the prospects for success and any drawbacks (limitations and  unwanted side effects; c.f., slides in Dr Robock’s presentation)