booklet 6- 3.1.1.3- the carbon cycle

Question 1

what physical factors impact stores and transfers in the carbon cycle?

Answer 1

• natural climate change (ice ages, el Nino + nina, milankovitch cycles, continental drift + weathering, permafrost melting)
• wildfires
• volcanic acivity

Question 2

explain natural climate change factors -ice ages, el Nino + Nina, Milankovitch cycles

Answer 2

ice ages- last one= 25,000 years ago
- colder temps= more ocean absorption of CO2= less in atmosphere
- warmer temps= melting ice, carbon released, more respiration, decomposition, ocean outgassing
- El Nino- short term warming phase= reduce CO2 absorption from oceans (La nina= opposite)
- milankovitch cycles- long term
–> earths orbit changes in 3 cycles which affects solar radiation= leads to glaciations (ice ages) + interglacial warming
(procession (wobbling of earths axis= changing time of seasons + range of temps.), eccentricity, obliquity (more tilt= warmer summers, cooler winters (vice versa))

Question 3

explain natural climate change factors - continental drift + weathering, permafrost melting

Answer 3

• continental drift + weathering
  –> long term tectonic movements affect ocean currents etc= alter carbon storage
  –> high mountains= more chemical weathering= more CO2 from atmosphere absorbed through carbonic acid reactions
  –> continents move= ocean currents shift= influence global carbon cycle + climate change
• permafrost melting
  –> short term
  –> cold periods = carbon locked in permafrost + ocean methane hydrates
  –> temps rise= permafrost melts= releases CO2 + methane= warming (positive feedback)–> occurs at arctic

Question 4

explain the factor wild fires

Answer 4

• short term
• burning= transfers carbon from biosphere to atmosphere as CO2 –> can turn areas from being carbon sinks to a carbon source
  BUT burning can encourage growth of plants long-term so wildfires are only a short term fluctuation in the carbon cycle.
• rising temps= increase wild fires= contributes to greenhouse gases into atmosphere –> more common in summer where lower levels of precipitation
  –> real world example= Los Angeles 2025 (January), 25 deaths, 12,000 structures destroyed, 180,000 buildings evacuated, $275 bn worth of damage, 40,588 acres burned