6.3 human activity altering the carbon cycle

Question 1

atmospheric carbon

Answer 1

concentration of atmospheric carbon strongly influences the natural greenhouse effect which in turn determines the distribution of temperature and precipitation.

the carbon balance is vital to the health of the earth in sustaining its other systems. it plays a key role in regulating the earths temp by controlling the amount of CO2 in the atmosphere. this balance is being increasingly altered by human actions

Question 2

the greenhouse effect

Answer 2

• short wave radiation passes through the atmosphere
• nearly 50% of short wave radiation is absorbed by the earths surface and warms it
• some radiation is reflected, passes through the atmosphere and gets lost in space as long wave IR radiation
• some long wave IR radiation is trapped by greenhouse gases and reflected back to earth: the direct effect is the warming of the earths surface and troposphere.
  !!!! humans are intensifying this to the point where the earth is becoming dangerously warm: disastrous consequences on entire ecosystems if this continues… since I.Revolution… 75% carbon emissions have come from burning fossil fuels

Question 3

importance of photosynthesis in maintaining a balanced carbon cycle

Answer 3

photosynthesis by terrestrial and oceanic organisms plays an essential role in keeping CO2 levels relatively constant therefore helping to regulate earths mean temp.

the amount of photosynthesis varies spatially, particularly with net primary productivity (this is the amount of organic matter available for humans and. other animals to harvest/ consume)
- NPP is HIGHEST in the WARM/WET parts of the world particularly in the tropical rainforests and shallow ocean waters. it is LOWEST in TUNDRA and BOREAL forests

Question 4

importance of soil health

Answer 4

soil health is an important aspect of ecosystems and a key element in the normal functioning of the carbon cycle
- soil health depends on amount of organic carbon stored within it. storage amount is determined by the balance between the soils inputs (plants/ animal remains, nutrients) and its outputs (decomposition, erosion and uptake by plant and animal growth)

carbon helps guide soil its moisture- retention capacity, structure and fertility. organic carbon is concentrated in the surface layer of the soil. a healthy soil has a large surface reservoir of available nutrient which explains why even a small amount of surface soil erosion can have such a devastating impact on soil health and fertility.

Question 5

fossil fuel combustion and its implications for the climate

Answer 5

fossil fuel combustion is the number one threat to the global carbon cycle. it is changing the balance of both the carbon stores and the fluxes.

the rate of carbon fluxing has sped up. additional CO2 in the atmosphere and its impact on greenhouse effect is largely responsible for a no. of climate changes:
- rise in mean global temp
- increased precipitation
- sudden shifts in weather patterns
- more extreme weather events
- amplification of current state, in the future wet regions will become wetter and dry areas drier.
- high pressure bands will have moved polewards

Question 6

fossil fuel combustion and its implications for ecosystems

Answer 6

these changes in climate have serious knock on effects on:
- sea level: rising because of melting ice sheets and glaciers, many major cities around the world are under threat from flooding
- ecosystems: decline in the goods and services they provide, a decline in biodiversity, changes in the distribution of species, marine organisms threatened by lower O2 levels and ocean acidification and the bleaching of corals etc

HYDROLOGICAL CYCLE: increased temp and evapo rates cause more moisture to circulate around the cycle, less cyrosphere storage, change in river discharge and capacity of terrestrial ecosystems