Carbon Cycling Flashcards
What is carbon cycling?
Key process in ecology
An intricately - linked network of biological, chemical and physical processes
Moves carbon among lithosphere (rocks, soil), hydrosphere (oceans, lakes, rivers) and atmosphere (air)
What does BIOGEOCHEMICAL cycle mean?
BIOlogy (fast) / CHEMICAL (slow) / GEOlogy (very slow)
What are the additions of CO2 to the atmosphere?
- Biological Inputs (e.g. respiration, decomposition)
- Geological / Chemical Input (e.g. volcanoes, mid - ocean ranges, weathering, erosion)
- Human Inputs (e.g. deforestation, burning fossil fuels, urbanization)
What are the removal of CO2 from the atmosphere?
- Biological Removal (e.g. photosynthesis, biomineralization)
- Geological / Chemical Removal (e.g. sedimentation, fossilization, mineralization)
What is the short - term Carbon Cycle?
Fastest component of the carbon cycle
Regulated by biological processes
Carbon cycles by the means of the complementary processes of photosynthesis and respiration
What are CO2 patterns in the atmosphere?
- CO2 levels in atmosphere show seasonal oscillations in northern hemisphere.
Photosynthesis is seasonal. Higher rates in spring / summer. Lower rates in fall / winter.
Respiration remains constant throughout the year.
What are the CO2 concentrations in the atmosphere?
Results of the study saw pattern of seasonal oscillation - spring high / fall low
What is cause of this increase in atmospheric CO2 levels?
Increase in atmospheric CO2 levels started in 1800s
Coincides with onset of Industrial Revolution
Correlates with increased use of fossil fuels by humans
How are humans are affecting the carbon cycle?
Sustained increase in atmospheric CO2 levels since 1958
Levels of atmospheric CO2 are 25% higher than 50 years ago
Human activity = driving force behind climate change through burning fossil fuels, forest fire and deforestation
How do we know that humans are responsible for recent changes in CO2 concentrations in the atmosphere?
Evidence = proxy measurements from ice cores agree with monitoring in Hawaii
Ice core drilled from a glacier in Antarctica, viewed under the microscope, glacial ice contains small bubbles that trap samples of air.
What is more evidence humans are responsible for climate changes?
More proxy measurements
Sediment cores preserve pollen grains and other plants remnants
Tree rings indicate age, wetness of season, droughts and seasonal growth
Coral reefs provide data on past ocean conditions
What is more evidence that humans are the reason for changing carbon levels?
Using carbon isotopes: C12, C13 and C14
Scientists have noted decrease in C13 and C14 over the last 40 years even though overall CO2 (with C12) levels increasing
Reduction of C13 levels suggest a non - geological source
Vegetation loses C14 over time. This suggests that burning a lot of ancient vegetation could give the C14 values observed.
Fossil Fuels have the right isotopic ratios of all carbon isotopes to explain observed results
What is the Long - term carbon cycle?
Chemical processes and geological processes drive long - term carbon cycling
What chemical processes regulate Long - term carbon cycling?
- Volcanism and mid - ocean ridges
- Slow oxidation of organic matter
- Chemical weathering
- Biomineralization - form carbonates and silicates
How have atmospheric CO2 level changed over time?
Fluctuations over last 400,000 years - involves gradual change influenced by longer term chemical and geological processes
Why is carbon cycle important to understanding of ecology and evolution?
Food webs trace carbon cycling through biological communities
Link ecology and evolutionary diversity
What other cycles are linked to carbon cycling?
Carbon cycling linked to oxygen cycling
Changes in oxygen levels link to evolutionary changes and biological diversity
Evolution of oxygen photosynthesis by Cyanobacteria - key to O2 accumulation in atmosphere
