Final answer:
If the amount of cloud cover increases in response to greenhouse warming, this will increase Earth's albedo and promote cooling. The correct answer is c) Increase, cooling.
Step-by-step explanation:
With an increase in cloud cover due to greenhouse warming, Earth's albedo increases, reflecting more sunlight, and promotes cooling, assuming that albedo effects are dominant in this scenario.
Albedo refers to the amount of sunlight that is reflected by a surface; a higher albedo means more sunlight is reflected back into space, which can lead to cooling. When cloud cover increases, more sunlight is reflected, leading to a higher albedo and potentially mitigating some of the warming caused by greenhouse gases. However, clouds can also have a warming effect by trapping heat, but since the question asks to assume that albedo effects dominate, the cooling effect is the focus here.
Therefore, C is the correct option.