Feedback In and Within the Carbon and Water Cycles Flashcards
What is positive feedback?
A natural response to a change in a systems equilibrium where the initial change prompts and causes further change.
What is negative feedback?
A natural response to a change in a systems equilibrium where the initial change is reduced, restoring equilibrium.
What is the positive feedback from increased fossil fuel burning?
Enlarged atmospheric CO2 store so increased temperatures. This causes more evaporation so more water vapour and clouds. This absorbs more long-wave radiation within the greenhouse layer, causing even higher temperatures.
What is the negative feedback from increased fossil fuel burning?
Enlarged CO2 store so increased temperatures. This causes an increase in NPP and therefore a reduced atmospheric store due to increased carbon sequestration. This means there is less long-wave radiation absorbed, lowering temperatures.
What state do systems stay in without human intervention?
Steady-state equilibrium - a long-term average state of balance, despite changes occurring within it.
What is a system threshold?
A critical level that, if exceeded, results in irreversible change. The latest evidence suggests that a global temperature rise of 1.5C would cross the threshold in the global carbon cycle.
What is a positive cryosphere feedback loop?
Increased temperatures cause sea and ice caps melt, so land and sea have a lower albedo and absorb more heat. This means that atmospheric temperatures rise, melting more ice.
What is a negative cryosphere feedback loop?
Increased temperatures cause sea and ice caps melt, so land and sea have a lower albedo and absorb more heat. This means that increased evaporation and cloud cover reflect solar energy, and sea temperature drops, cooling the air in contact with it and decreasing melting.
What is a positive terrestrial feedback loop?
Global temperatures rise, warming tundra areas and increasing decomposition. This increases CO2 in the atmosphere, raising temperatures.
What is a negative terrestrial feedback loop?
Global temperature rise means that the coniferous forest biome migrates northwards and expands, so the biomass CO2 store expands.
What is marine carbon feedback?
Warmer oceans releasing more carbon dioxide contribute further to climate warming. Acidification impacts on the health of marine ecosystems, which reduces carbon sequestration and can impact on the biological ocean pump.
What is methane feedback?
Large amounts of methane are stored in permafrost, which is released when climate change causes melting. Increased methane raises the atmospheric temperature, melting more permafrost. This could take Earth’s climate past its threshold point.
What are the implications of feedback within and between the two systems for life?
CC impacts vegetation patterns.
Melting ice caps cause eustatic sea level change.
Reduction in ice reduces annual meltwater supply.
Extreme weather events more prevalent.
Ocean temperature change affects circulation patterns.
