ESS205 NOTES PACKAGE for 1 ST MIDTERM

Lecture 1 Notes  Course is about exploring the consequences of human activity on planet Earth  Issues covered will include climate change, pollution, and depletion of natural resources.  Changes happen every time and everywhere  Humans are aware of their impact on Earth  Need the right tools and understanding of context(the difference between Earth now and Earth in the beginning) to properly assess the impact  The Earth System: four major interacting parts, with flows of matter and energy between them  Lithosphere, Atmosphere, Hydrosphere, Biosphere  Lithosphere: the solid earth  The upper part of the solid earth, which interacts with the other components of the earth system  Atmosphere: a mixture of gases  Hydrosphere: Earth’s water  Biosphere: organic matter  Two key sources fuel Earth system  External energy from solar radiation: drives the hydrologic cycle and the circulation of ocean and atmosphere; in turn that causes erosion of land surfaces  Internal energy from radioactive decay: drives volcanism and plate techtonics  Example of interaction: sand (the lithosphere) from Africa nourished the Atlantic Ocean (the hydrosphere) with iron  Global Change: the modification of the Earth’s components and of the interactions between the components, both natural and human-induced  Change is a typical characteristic of Earth  Types of change  Gradual: takes place over long period of time  Catastrophic: takes places rapidly  Unidirectional: Harry Styles (evolution)  Cyclic: supercontinental cycle, sea-level cycle, glacial-interglacial cycle  Beginning of time: universe was created from the Big Bang  Small, dense collection of matter and energy suddenly exploded  Evolution of Earth can be divided into stages known as eons and eras  Hadean Eon: oldest time as we know it (4.6 to 3.8 billion years ago)  “Hell on Earth”: Earth very hot, chemicals forming, no oxygen,  Internal Differentiation: much radioactive decay and the molten state of Earth led to heavier elements such as iron and nickel settling down in the Earth’s core  Conditions at Surface: magma ocean at first, thin crust as Earth cooled, atmosphere formed except without oxygen yet  Archean Eon: (3.8 to 2.5 billion years ago)  Water and oceans appear  Intense greenhouse effect  Carbon cycle: made Earth hospitable  First evidence of life appears about 3.8 billion years ago from rocks in Greenland, photosynthesis occurs 2.4 billion years ago to first release oxygen!  Proterozoic Eon (2.5 to 0.55 billion years ago)  Large volume of iron  Eurkaryotic (multi-cellular) cells appear, exponentially increasing oxygen in the atmosphere and ocean  Small invertebrates  Phanerozoic Eon (545 million years ago to present)  Visible life (ie animals, plants, humans, etc.) Lecture end around this time Lecture 2 THE CENOZOIC ERA (65 Ma – present) Recap  2.5 : enough oxygen in the atmosphere to have an ozone layer  Proterozoic : low oxygen atmosphere but an ozone layer – so life is now protected from dangerous UV layers \  Evolution of periotic cells – photosynthesis good at converting energy from the sun  Evolution of multi-cellular life  What was major change in this period?  Paelozoic – major animal groups evolve  Anphibeans, fish and reptiles all evolving  Warm in-land seas  Relatively warm period  Around 400 – 450 evolution of land plants – so surface of planet changes dramatically  All the continents forming all Pangea  End of this : largest extinction  Pangea breaks apart then Mesozoic – age of dinos and reptiles  Extreme warmth on the planet  End of Mesozoic – another extinction – meteor?  Caenozoic: today  The Cenozoic Era (65 Ma – present)  The era we live in  It started off warm with no ice or no permanent ice sheets