Briefly outline how the natural greenhouse effect operates. 

Explain how the global energy balance can be changed by solar radiation variations.

Explain how the global energy balance can be changed by global dimming due to volcanic eruptions.

Explain two reasons why sea-level change may result from global warming.

Reason 1:

Reason 2:

Longwave/outgoing radiation [1] is absorbed by greenhouse gases [1], heating up the atmosphere [1].

Solar flaring / sunspot activity / solar cycles or increase/decrease in solar activity [1] can change the amount of shortwave radiation entering the system [1].

Increased aerosols / dust / particles in the atmosphere [1] preventing the input of shortwave radiation [1].

In each case, credit a valid reason [1] and award [1] for development/exemplification that explains change in sea level.

For example:

• Thermal expansion of the oceans [1], as at higher temperatures water occupies a greater space/sea level rise [1].
• Melting of icecaps/glaciers [1] results in a global change in hydrological storage as water moves from the cryosphere to the oceans / increases the amount of water in the oceans/sea level rise [1].

Accept evaporation and drop in sea level ONLY when specifically related to inland seas.