booklet 1- water and carbon cycle as natural systems 3.4.1 Flashcards
what are systems
simplify complex processes, interrelationships, situations
what are 4 subsystems
- biosphere
- hydrosphere
- lithosphere
- atmosphere
- cryosphere
subsystems- biosphere
- living things
- where life exists from above earth’s surface to below it
- humans, fungi, animals, plants
subsystems- hydrosphere
- all water on earth in any state found in oceans, atmosphere, groundwater etc
subsystems- lithosphere
- land
- earths relatively hard outer layer e.g. limestone (calcium carbonate), hydrocarbons (fossil fuels), marine sediments from shells + marine life
subsystems- atmosphere
- layer of gases + suspended solids that surrounds earth
subsystems- cryosphere
all frozen components of the earth e.g. frozen rivers, lakes, snow, glaciers, frozen soil (permafrost) etc
what are components of a system
- transfers (flows–> movements of parts of the system
- stores (components)
- outputs (matter/energy moving from the system to outside to another system
- inputs (matter/energy moving into a system from outside)
- boundary (limits to the system e.g. watershed)
types of systems
open
closed
cascading
open system
where matter + energy are allowed to transfer across the system boundary and into the environment
input –> store -(flow)-> store –> output
closed system
- where there may be a flow into/out of system but no matter flow takes place across the boundary
- fixed mass
input –> store –> output –> input –> store output
cascading system
where energy + matter are transferred from one subsystem to another –> output of one subsystem= input of another subsystem
e.g. river debris cascades into coastal systems
feedback loops what are they
try to maintain/restore equilibrium
positive feedback
- amplifies (multiplies) the change
- change becomes bigger and moves the system further away from the balance
e.g. global warming –> increases permafrost thawing –> releases methane to atmosphere –> causes more warming
negative feedback
- nullifies a change
- decreases the effects of the change keeping system closer to previous state
e.g rock has freeze thaw weathering –> debris covers rock –> debris acts as protection –> nullifies further weathering
dynamic equilibrium
- whole system may change to another system
- when inputs = outputs in a system then it is in equilibrium
- flows and processes continue in same way at all times, there’s no overall change to the system
dynamic equilibrium in reality
- lots of small variations in inputs + outputs of a system
- variations are usually small so inputs + outputs remain about balanced over a longer period
- BUT large, long term changes to balance of inputs + outputs can cause system to change
–> it will then establish a new dynamic equilibrium
–> changes can trigger positive/negative feedback
siberia forest fires how do they cause a threat?
- they create positive feedback
- fires release greenhouse gases e.g. CO2 –> more carbon in atmosphere –> atmosphere warms –> more forest fires + more carbon released –> cycle continues
albedo
- when snow + ice + vegetation reflects solar radiation
- snow has albedo 80%
- Arctic has a high albedo as it has lots of ice + snow
–> this is decreasing due to melting ice –> means more solar radiation can reach ground –> this warms earths surface –> more ice melting + less albedo –> cycle continues
negative feedback example
- high temps= more vegetation grows= captures more CO2
siberias melting permafrost
- permafrost= stores carbon + when it melts releases methane. it is ground that remains below 0 degrees for at least 2 years. It’s found beneath 24% of exposed land area (Northern hemisphere)
how is it an issue?
-melting permafrost releases methane –> methane= greenhouse gas that traps more heat in atmosphere than CO2 –> leads to enhanced greenhouse effect (positive feedback) –> more heat in atmosphere= more permafrost melts, more methane in atmosphere, cycle continues
