Feedback processes either enhance (positive feedback) or weaken (negative feedback) the effect of climate change triggers.
Feedback processes can be elaborate and work within a complex system of multiple variables, some of which we understand, and some of which we are only beginning to understand.
We’ve all heard sound feedback when someone puts a microphone too close to the speaker. You hear a painful squeal. Sound from the speaker is picked up by the microphone, amplified and sent back to the speaker. This amplified sound is again picked up by the microphone causing a positive feedback loop – and that annoying sound.
Understanding climate feedbacks is not only important to explaining the climate change that we are currently observing, but is also important when considering what could happen in the future.
As global warming occurs, the amount of water vapour in the atmosphere increases because warmer air can hold more moisture. Water vapour is also a very effective greenhouse gas, so it contributes to further warming.
This positive feedback process is extremely important to consider as water vapour is the most abundant of all greenhouse gases in the atmosphere and plays an important role in enhancing the warming that we are currently observing.
Water vapour will undoubtedly also play an important role in future warming since the climate is expected to continue to warm. (1)
Snow and ice
Snow and ice have a high albedo, which means that they reflect a large amount of incoming solar radiation back into space.
As snow and ice disappear in response to a warming climate, lower albedo (i.e. darker coloured) surfaces beneath the snow and ice are exposed.
Lower albedo surfaces absorb more solar radiation, thus contributing to surface warming, which then speeds up the disappearance of snow and ice even further.
This process is being observed in places like the Arctic today, where reduced ice and snow cover contribute to increased warming in these sensitive climates.