1 / 16

Honors 1360 Planet Earth Last time: Origins of Life :

Honors 1360 Planet Earth Last time: Origins of Life : Obs : Minerals deposited before 2.2 Ga require ~ no O 2 in the early atmosphere Obs : Organisms “near the roots” of the DNA tree tend to be hyperthermophilic & use methane or hydrogen plus

zubaida-heba
Download Presentation

Honors 1360 Planet Earth Last time: Origins of Life :

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Honors 1360 Planet Earth Last time: Origins of Life: Obs: Minerals deposited before 2.2 Ga require ~ no O2 in the early atmosphere Obs: Organisms “near the roots” of the DNA tree tend to be hyperthermophilic & use methane or hydrogen plus reduced metals for energy (not CO2-H2O photosynths) Hyp: Eukaryotic photosynths (and O2) become sufficiently commonplace to change the atmosphere ~ 2.2 Ga! Life & Climate: Obs: Faint young sun paradox: Early sun was weaker, but glaciation observed only in a few (later) short epochs Obs: History of O2 and CO2… First glaciations coincide with first rise in O2; later glacial epochs with low CO2 periods Hyp: Life exerts a primary control over Earth’s climate! 05 December 2008

  2. Honors 1360 Planet Earth • Last time (Cont’d): • Life on Earth & Climate Feedbacks • The Forcing is Different Now than in the Past: • ~13% of the Global Annual Respiration Cycle • Is Removed from Storage in Sedimentary Rocks • and Added to Atmospheric CO2 Each Year • But the biological feedbacks are similar: • Ice core and other data suggest biological • feedbacks on CO2, Methane, SO2 are all positive: • Higher temperature leads to higher concentrations • of greenhouse gas until a new “stability” is reached. • Today: • A quick review of global change from the IPCC • Enough dire & dour, gloom & doom: • Reducing CO2 emissions: Can we do it?

  3. Beginning ~1900 we changed the inputs: Bio-CO2 (+)  Ice Albedo (+) ~60 Gt/yr in; 60 Gt/yr out 8 Gt/yr CO2! Earth Climate System Solar Energy Bio-SO2 (+) Bio-CH4 (+) The PHYSICS of how an increase X in ppm atmospheric CO2 increases radiative forcing is well understood… The biological feedbacks are not.

  4. Biological feedbacks on modern climate: • IPCC: On Land • Changes in Land Surface (vegetation, soils, water) • change radiation (albedo), cloudiness, surface temperature • Changes in surface vegetation change water, energy • dynamics. Boreal forest reduces albedo (warms)… • Increased temperature may increase or slow both • photosynthesis or respiration: Depends on Soil Moisture • Ecosystem shifts may ↑ or ↓ CO2; • ecosystem models predict long-term net ↑ storage of C • but short-term vegetative die-back may release large • amounts C if changes are rapid • Evidence for growth of the net natural land carbon sink • (0.3 GtC/yr in 1980’s, 1.0 GtC/yr in 1990’s) • Net Uncertain!

  5. IPCC: Oceans • 1ºC increase in sea surface temperature → 10 ppm ↑ CO2 • by degassing • Marine organisms absorb 50 Gt C/yr! • Uptake is P, N, or Fe-limited • depending on where • Biological pump is insensitive to CO2 concentrations but • may be sensitive to temperature, cloud cover, currents, UV, • acidity… • Net Uncertain!

  6. BUT THIS IS A PRETTY STRONG CLUE:

  7. Global Change: A Quick Review (The most recent executive summary from the last month’s winners of the Nobel Peace Prize)

  8. 1998 report from ncpa.org (a “free- market” think tank) looking at expected cost of Kyoto CO2 abatement: 1998 oil cost: (1995)$16.80 Today’s price: (1995)$68.21

  9. From “The McKinsey Quarterly” (online journal of business management strategy)

More Related