I have recently posted two "climate feedback loop" fact sheets. One described the ice/albedo feedback and the other discussed the methane loop. These are examples of positive feedback (or runaway feedback), effects that tend to amplify climate change.
The feedback effects shown below deal with humans causing an increase in the amount of water vapor in the atmosphere. Here are two positive feedback loops (increased water vapor and increased cirrus clouds) and one negative feedback loop that tends to counteract global warming (the formation of low, thick, stratus clouds that reflect sunlight). There is uncertainty about which types of clouds will form, but it is likely that both are possibilities, depending on meteorological conditions.
Climate Feedback I: Water Vapor. © Fred Montague