• What is the Carbon Cycle?
  • -Carbon moves in complex chemical and physical transfers from sources or reservoirs, where carbon is released, to sinks, where carbon is taken up. This movement is the global carbon cycle.
  • Credit: NASA (Earth observatory)
  • -The global carbon has been exchanging following major reservoirs of carbon such as
    : The atmosphere
    : The terrestrial biosphere
    : The oceans
    : The sediments
  • -The carbon exchanges between reservoirs occur as the result of various chemical, physical, geological, and biological processes. The ocean and terrestrial biosphere contain the largest active pool of carbon near the surface of the Earth. The natural flows of carbon among the atmosphere, ocean, and sediments is fairly balanced.
  • Credit: NCAR, USA (left) and Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany (Right)
  • Credit: NCAR, USA (left) and Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany (Right)
  • Why we should study the Carbon Cycle?
  • -CO2 in the atmosphere acts like a blanket over the planet by trapping longwave radiation, which would otherwise radiate heat away from the planet. While CO2 is only a very small part of the atmosphere (0.04%), it plays a large role in the energy balance of the planet. CO2 concentration rises and falls about the same amount each year due to seasonal changes in photosynthetic rates. Each year, however, the total amount of atmospheric CO2 is greater than the year before.
  • Credit: Carbon Dioxide Information Analysis Center, Oak Ridge National laboratory
  • -Moreover, many uncertainties in the carbon cycle feedbacks in state-of-art numerical models. Therefore, improved and accuracy coupled climate-carbon models are needed to simulate future climate change.
  • Credit: Coupled Climate Carbon Cycle Model Intercomparison Project
  • Earth System Model
  • -Earth System Models are sets of equations describing processes within and between the atmosphere, ocean, cryosphere, and the terrestrial and marine biosphere. These underlying equations contain information about physical, chemical (carbon cycle) and biological mechanisms governing the rates of change of the elements of the Earth System.
  • Seasonalcycle of Carbon dioxide in ESM
  • -CESM-BGC (Community Earth System Model ? Biogeochemical) reasonably reproduces reducing concentration of carbon dioxide in the atmosphere over Northern hemisphere due to growth of plants
  • -According to photosynthesis of plants, seasonal cycle of carbon dioxide flux over land changes. For instead, the terrestrial biosphere in Northern hemisphere is uptake carbon dioxide from atmosphere during boreal summer. In contrast, Amazon and the east part of Australia show negative carbon flux due to growth of plants.
  • -The Eastern equatorial Pacific and the northwestern Arabian Sea are the most intense carbon dioxide source areas by phytoplankton. This intensity is more enhanced in boreal summer. Strong sink area are located in the transition zone between the subtropical gyre and subpolar waters (40N-60N and 40S-60S), negative carbon dioxide flux are formed by the cooling of warm waters with the biological drawdown of carbon dioxide in the nutrient-rich subpolar waters.
  • References
  • -Takahashi et al. (2002), Global sea-air CO2 flux based on climatological surface ocean pCO2 and seasonal biological and temperature effects, Deep-Sea Research II, 48, 1601-1622
    -Dunne J. P. et al. (2012), GFDL’s ESM2 Global Coupled Climate Carbon Earth System Models. Part II: Carbon system formulation and baseline simulation characteristics, Journal of Climate, 25, 6646- 6665
    -Cadule P. et al. (2010), Benchmarking coupled climate carbon models against long term atmospheric CO2 measurements, Global Biogeochemical cycles, 24, GB2016, doi:10.1029/2009GB003556
    -Richard B. N. et al. (2010), Description of the NCAR Community Atmosphere Model (CAM 5.0), NCAR TECHNICAL NOTE, NCAR/TN-486+STR
    Updated at June 28. 2013
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