Prof. Fleming's lecture slides 12/7/07

Prof. Fleming's lecture slides 12/7/07 - The co-dependency...

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The co The co -dependency of plant storage of carbon and dependency of plant storage of carbon and long long -term CO term CO 2 concentration in the atmosphere creates concentration in the atmosphere creates a regulation mechanism which checks runaway changes a regulation mechanism which checks runaway changes in CO in CO 2 and catastrophic planetary warming. and catastrophic planetary warming. from from “Feedbacks and the Feedbacks and the coevolution coevolution plants and atmospheric CO plants and atmospheric CO 2 D.J. D.J. Beerling Beerling & R.A. & R.A. Berner Berner PNAS, PNAS, 102 102 1302 (2005). 1302 (2005).
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Photosynthesis 101 22 6CO 6H O + Efficient: ~90% of energy absorbed is used to initiate photochemistry Fast: Turnover rate of photosynthesis : ~ 100-300/sec Regulated: ~75% of absorbed energy can be dissipated with a 1sec response time 61 26 2 CH O 6O + light
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Earth is formed Life emerges Photosynthesis Cyanobacteria Oxygen-rich atmosphere Plants Dinosaurs Hominids, 3pm Homo Sapiens, 11:38 pm US 11:59:58 pm Age of Earth 4.55 billion yrs
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Atm CO 2 abundance 200 ppmv last glacial max 280 ppmv Pre- industrial 315 ppmv 1957 380 ppmv 2006
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Economic Productivity and CO 2 GDP = C ×(E/C) ×(GDP/E) To increase economic productivity (GDP) without increasing carbon emissions (C), we must increase – The amount of energy produced per unit carbon emitted (E/C) – The economic productivity of energy (GDP/E) We need a research and development program aimed at increasing GDP in a carbon-constrained world Hoffert et. al. Science 298 :981-987, 1 Nov 2002
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Total Primary Power vs Year 1990: 12 TW 2050: 28 TW
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US where we want to be
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Energy Reserves and Resources 0 50000 100000 150000 200000 (Exa)J Oil Rsv Res Gas Gas Coal Coal Unconv Conv Reserves/(1998 Consumption/yr) Resource Base/(1998 Consumption/yr) Oil 40- 78 51- 151 Gas 68- 176 207- 590 Coal 224 2160 Rsv=Reserves Res=Resources Reserves: are found and proven in the ground as of present time with 90% certainty . Resources: include what is estimated with 50% confidence that it will exist when needed and is extractable from the earth. Source: World Energy Assessment Report (UN Development Program et al.)
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Photosynthesis 101 22 6CO 6H O + Efficient: ~90% of energy absorbed is used to initiate photochemistry Fast: Turnover rate of photosynthesis : ~ 100-300/sec Regulated: ~75% of absorbed energy can be dissipated with a 1sec response time 61 26 2 CH O 6O + light
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Early Observations Action spectrum for O 2 production / Photosynthesis Engleman (1883) Chlorophyll and carotenoids are involved. Result : 2480 molecules of Chl per molecule of CO 2 reduced [or O 2 evolved] per flash Conclusion: Either quantum efficiency is very low OR Most of the Chl is not absorbing light Gaffron & Wohl (1936) Hypothesis: Photosynthetic Unit (PSU) is comprised of several thousand molecules Emerson & Arnold (1932): 10 μ s Flash Lamp Experiments: Duysens (1952) PSU contains 200-300 Chl per ‘reaction center’.
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An Abstract Question: How much Chl is in Picasso’s tree ?
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Prof. Fleming's lecture slides 12/7/07 - The co-dependency...

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