Carbon Dioxide Friend or Foe The terrestrial carbon

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

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 – Ch. EAS <ch. EEz> – ACME 2007 • Conclusion – CO 2, Friend or Foe?

OVERVIEW

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

Overview • Carbon Dioxide – 0. 04% of atmosphere, but quite important

Overview • CO 2 and climate are closely linked

Overview • A climate for change

THIS CLIMATE FUTURE OVER THE NEXT 100 YEARS IS HIGHLY DEPENDENT ON: 1) HUMAN ACTIVITIES AND THE RESPONE OF THE…

LAND CARBON CYCLE

Land Carbon Cycle • Process of photosynthesis of land ocean plants makes life possible on this planet • CO 2 + H 2 O + light -> Carbohydrate + O 2 + heat • Metabolism of carbohydrates and oxygen by plants and animals completes the loop

Land Carbon Cycle

Land Carbon Cycle • Atmospheric CO 2 growth not constant – more variable than rate of increase in fossil fuel • Land ocean sources/sinks – complex feedbacks – affected by episodic (volcano) and oscillatory (ENSO) events – Where’s the sink?

Land Carbon Cycle

Land Carbon Cycle • Missing sink… (Sarmiento et al, 2002)

Land Carbon Cycle

Land Carbon Cycle • Peters et al, 2007

Land Carbon Cycle • Courtesy of NTSG, U. Montana

Land Carbon Cycle • Sanders et al, 2002

Land Carbon Cycle • Friedlingstein et al, 2005 – Who stole my sink?

Land Carbon Cycle

Land Carbon Cycle • Fluxnet

CASE STUDIES

Case Study: Ch. EAS

Case Study: ACME 2007

Case Study: ACME 2007 CO 2 MORNING UPWIND AFTERNOON DOWNWIND

CONCLUSION

Conclusions • Future climate change dependent on how we manage the atmospheric carbon cycle • Land-atmosphere interaction strongly implicated in controlling atmospheric CO 2 growth rates • Big picture is understood but the devil is in the details • Lots of interdisciplinary science needed • CO 2, Friend or Foe? You decide…