1. Development of the Ecosphere: Timeline and processes occurringa. 15 billion years ago…i. Big-Bangb. 4.6 billion years ago……i. Solar systems & earth was formedc. 3-4 billion years ago…i. Oceans and lands were formedii. Continents started to formd. 3.1-3.5 billion years ago…i. First evidence of life..(single cellsà bacteria, algae)e. What is life??f. What were the conditions for life?i. 4 billion years ago……1. The atmosphere was made off: 2. Water vapor3. Ammonia (NH3)4. Methane (CH4)5. Hydrogen sulfide (H2S)6. Hydrogen gas (H2)7. Carbon monoxide (CO)8. **Very little O2 & N2g. 3.1-3.5 billion years ago…i. Single cellsà algae were able to 1. Anaerobic metabolism (produce E w/out O2)2. Take C-H20(simple organic molecules)à CO2 + alcohols & energyii. For ~800 millions of years, CO2 was released (as by-products of the metabolism) & built up in the atmosphere and oceansh. 2.3 billion yrs ago….There was enough CO2 in the atmosphere to sustain life….i. Single-cells (blue-green algae)à photosynthesisCO2 + H2O--àCH2O + O2àbuilt upii. Initially, the released O2 was lethal to the living organisms (terminar la idea)i. 1.9 billion yrs ago…..i. Ozone (O3) layer is being built in the stratosphere1. Filters out the UV radiationà make life possible on landàdevelopment of O2 tolerant organismsj. 1.3 billion yrs ago….i. Aerobic respirationCH2O + O2 à CO2 + H2Ok. 600 mill yrs ago…..i. Life is widespread in the oceans1. Single cells2. Early fishes3. Large algael. ~420 mill yrs ago….i. Life is widespread on Land1. Earliest plants2. Invertebrates3. Vertebrates m. ~350 mill yrs ago…i. Development of tropical rainforestà fossil fuel à today’s oiln. ~200 mill yrs ago…i. Colonization of larger vertebrates2. Date of Separation according to Mitochondrial DNA3. Early Human Phylogeny 4. Expansion of Human Habitat (old theory) 5. At 18,000 years ago, the Earth looked like this map from Earth and Life Through Time6. Food Chain of Land Animals 7. World Population Trend from 10,000 B.C. to 200 A.D.8. First civilization collapse..a. Eastern Islandb. Mayas Empire9. UN, World Population Prospects:199210. Why has climate change?a. Meteorite impacts (very infrequent & random)b. Hugh Volcanic eruptions (more frequent, but still random)c. Enough evidence of glacial and interglacial periods for the last 2-3 mill yrsi. Hypotheses, Theories, & Laws…the same?11. Milanković cycles (Theory)Performed detailed calculations concerning the periodicity of the earth’s orbital parametersa. Precession: 23,000 yrs i. It’s a ‘slowing down’ of the rotation of the earthà tilt of the earth point to various directions (like the axe of a spinning top)b. Axial tilt: 41,000 yrsi. The greater the angle of the tiltà the greater the potential for extremes in seasonal climate (especially for polar regions)c. Eccentricity: 100,000 yrs i. During periods of high eccentricityà higher differences between max & min distance from sun to earthà more potential for extreme (cold & warm) climate12. Evidence of glaciations?a. Swiss hunter in the Alps (1815) associated scratch marks on rocks with thePressure due to weight of ice13. How do scientists track glaciation?a. Stable-isotopes from zooplankton (tiny shells of calcite)b. Come from seawaterc. Once deadà built up on the ocean bottom as layers (~2.5 cm or 1” = 1,000 yrs)d. Lighter Oxigen (16O) evaporates with water vapor (due to insolation) and then precipitates as either:a) rain and returns with rivers and groundwater to oceansà seawater remains the ~same (interglacial) [e.g. now]Or b) snow and accumulates and does NOT return to oceansà seawater change rate between 16O & 18O14. Comparison between O2 isotope record & Milanković
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