Ankur Desai, UW-Madison

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Carbon Dioxide, Friend or Foe?
The terrestrial carbon cycle and a climate for
life on Earth

• Ankur Desai, UW-Madison
• AOS 405, 6 Feb 2008

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Outline

• Overview
• Science at the boundaries
• A climate for change
• The land carbon cycle
• A climate for life
• Who stole my sink?
• Some case studies
• ChEAS ltchEEzgt
• ACME 2007
• Conclusion
• CO2, Friend or Foe?

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OVERVIEW
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Overview

• Lots of good science at the boundaries
• Land-ocean-atmosphere interaction is a good
  example
• Transfer of energy, mass, momentum have large
  uncertainty
• And large effects on meteorology and climate
• Atmospheric perspective spans fields of
  micrometeorology, boundary layer meteorology,
  oceanography, and biophysics

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Overview

• Carbon Dioxide
• 0.04 of atmosphere, but quite important

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Overview

• CO2 and climate are closely linked

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Overview

• A climate for change

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THIS CLIMATE FUTURE OVER THE NEXT 100 YEARS IS
HIGHLY DEPENDENT ON1) HUMAN ACTIVITIESAND THE
RESPONE OF THE
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LAND CARBON CYCLE
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Land Carbon Cycle

• Process of photosynthesis of land and ocean
  plants makes life possible on this planet
• CO2 H2O light -gt Carbohydrate O2 heat
• Metabolism of carbohydrates and oxygen by plants
  and animals completes the loop

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Land Carbon Cycle
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Land Carbon Cycle
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Land Carbon Cycle
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Land Carbon Cycle
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Land Carbon Cycle

• Atmospheric CO2 growth not constant
• more variable than rate of increase in fossil
  fuel
• Land and ocean sources/sinks
• complex feedbacks
• affected by episodic (volcano) and oscillatory
  (ENSO) events
• Wheres the sink?

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Land Carbon Cycle
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Land Carbon Cycle

• Missing sink (Sarmiento et al, 2002)

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Land Carbon Cycle
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Land Carbon Cycle
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Land Carbon Cycle

• Peters et al, 2007

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Land Carbon Cycle

• Courtesy of NTSG, U. Montana

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Land Carbon Cycle

• Sanders et al, 2002

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Land Carbon Cycle

• Friedlingstein et al, 2005
• Who stole my sink?

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Land Carbon Cycle
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Land Carbon Cycle
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Land Carbon Cycle

• Fluxnet

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CASE STUDIES
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Case Study ChEAS
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Case Study ChEAS
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Case Study ChEAS
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Case Study ChEAS
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Case Study ChEAS
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Case Study ChEAS
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Case Study ACME 2007
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Case Study ACME 2007
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Case Study ACME 2007
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Case Study ACME 2007
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Case Study ACME 2007
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Case Study ACME 2007
CO2
MORNING UPWIND
AFTERNOON DOWNWIND
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CONCLUSION
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Conclusions

• Future climate change dependent on how we manage
  the atmospheric carbon cycle
• Land-atmosphere interaction strongly implicated
  in controlling atmospheric CO2 growth rates
• Big picture is understood but the devil is in the
  details
• Lots of interdisciplinary science needed
• CO2, Friend or Foe? You decide