Air warms a little. What does extra water vapour do next?

• It leaves the atmosphere at once
• It blocks all sunlight and freezes Earth
• It traps more heat and warms more

Volcanic particles block sunlight, then extra vapour traps heat. Which is the forcing?

• The blocked sunlight, which started it
• The extra vapour, since it came first
• Both are feedbacks, since both involve air

Melting ice slows warming because dark water reflects more sunlight.

Ice melts and exposes dark ocean. Which way does this push temperature?

• Down, since water evaporates at once
• Up, since dark absorbs more heat
• Nowhere, since color cannot matter

A big eruption cools Earth briefly. Why call it a push from outside?

• Eruptions never affect the energy balance
• Volcanoes sit outside planet Earth
• It starts the change from outside

What does climate sensitivity summarize?

• How much warming a push causes after feedbacks
• How thermometers react to sunlight
• How many clouds appear each day

A glacier retreats as greenhouse gases rise. How do you split forcing from feedback?

• The retreat is the forcing and gases are the feedback
• Added gases are the forcing and reflectivity changes are the feedback
• Both are forcings, so no split is needed

A friend says the sensitivity range exists because CO2 was never measured. What is wrong?

• CO2 has never been measured anywhere
• The range comes mainly from clouds, which can warm or cool
• A range means models show zero warming