Lecture 5: System Feedbacks Flashcards
What is a negative feedback loop?
Where the response affecting a stimulus either slow or stop that stimulus.
What is a positive feedback loop?
Where the response affecting a stimulus increases that stimulus.
What is the positive feedback loop between temperature and water vapour?
Increased temperatures increase water evaporation, and more water vapour in the atmosphere acts as a greenhouse gas and traps energy, thus further increasing temperature.
What is the positive feedback loop between climate change and wildfires?
Increased dryness and heat causes more wildfires to erupt and the burning of biomass releases CO2, which is a greenhouse gas that further exacerbates climate change.
What is the positive feedback system between surface temperature, plant decomposition and GHG production?
Increased surface temp promotes plant decomposition (higher temp = increased reaction rate of decomp), which releases GHGs, thus further increasing surfacing temperature through the greenhouse effect.
What is the positive feedback loop between global temperature, continental snow/ice cover and planetary albedo?
Increased global temp melts the snow/ice covering the planet, which decreases planetary albedo, causing more solar radiation to be absorbed, increasing the global mean temperature.
What is the negative feedback loop between prey and predator populations?
When prey population increases, there is an abundance of food for the predator population, causing them to grow, which in turn decreases the prey population.
What is the feedback system between surface temperature, evaporation rate, and low-level cloud cover? Is it positive or negative?
Increased surface temp causes increased water evaporation rates, which increases low-level cloud cover, which traps heat and increases surface temperature.
POSITIVE LOOP.
What is the feedback loop pertaining to the daisyworld model?
Solar luminosity increases surface temperature, which increases daisy growth. However, if too many daisies grow, the earths albedo decreases, thus decreasing the surface temperature, which causes the daisy coverage to decrease. This decreased daisy coverage decreases the earth’s albedo, thus increasing the surface temperature and promoting daisy coverage.
NEGATIVE FEEDBACK LOOP.
