1-27 Earth environmental systems 2 slides

1-27 Earth environmental systems 2 slides - Earth Earth’s...

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Unformatted text preview: Earth Earth’s Environmental Systems II– Systems II– Scales, Systems, Cycles Cycles ENV200H1S – January 27, 2011 1 Announcements Announcements Tutorial #1 - finishing up today Note RL 14081 (T0701C – Thur@12) is on the 14th Floor of Robarts Library, bring your TTcard to get entry Will be posting Tutorial #2 worksheet early next week Did you forget your recorder in class on Tues? Guest announcement by Prof Tony Davis to discuss summer field course in Ecuador/ Ecuador/Galapagoes 2 Outline Earth’s Environmental Systems Scales of time Earth Sciences S stems Sy Thermodynamics 3 The The Long Now Foundation www.longnow.org/about/about.htm The Long Now Foundation hopes to provide counterpoint counterpoint to today's "faster/cheaper" mind set and promote "slower/better" thinking. hope to creatively foster responsibility in the framework of of the next 10,000 years. 4 The The clock of the long now www.longnow.org/about/about.htm I want to build a clock: that ticks once a year that has a century hand that advances advances once every hundred years, with a cuckoo that comes comes out on the millennium. When I tell my friends about the millennium clock, either they get it or they don't. (Danny Hillis) "The Millennium Clock" from Wired Magazine (1995) 5 Trying Trying to understand “deep time” www.longnow.org/about/ 6 If If we really could condense 4.5 billion billion years into a single year: 1 Jan 00:00:00 - the Earth is a molten mass 00 th It takes a month for the Earth to cool sufficiently for rocks to form. sufficientl It takes another month for the oceans to accumulate, accumulate, to set up the hydrologic cycle and for interactions between what was an acidic acidic atmosphere and a basic lithosphere to neutralize the environment. 7 1 Mar - appearance of primitive, single celled lifeforms (but the Earth is still cell (b anaerobic, anaerobic, there is no oxygen in the atm atmosphere). From Mar to May primitive plants create create sufficient ox gen in the oxygen atmosphere atmosphere to allow formation of the ozone ozone layer – creation of a two layered atmosphere atmosphere (troposphere and stratosphere) which cuts off input of ionizing radiation 1 June (50% of the Earth’s lifetime has passed) when we enter the Precambrian (pre(pre-life) era. 8 •1 Aug move into the Aug move into the Cambrian Cambrian • Slide through the age of fishes, land plants (carboniferous), age of amphibians, amphibians, insects, reptiles and birds. • How late in the year How late in the year do do the dinosaurs go extinct? extinct? 9 19 December!! 97% of the Earth’s history is past when the dinosaurs go. Yet the extinction of the dinosaurs is about as far back as most of us can even imagine (65 back million + years ago). Humans appear on 31 Dec at 8:00 p.m. Common Era (which began 2010+ years ago) begins begins 11:46:00 (14 minutes to midnight) 10 Industrial Revolution 11:59:58 (1.2 seconds to midnight) How can Earth’s systems possibly adapt to the mass perturbations that humans have caused in such a “short” time? How can we even comprehend how the Earth will respond? 11 •Earth is organized into crust, mantle and core. •Crust & upper mantle = lithosphere 12 •Thin crust of rock floating atop a malleable mantle mantle surrounding a molten core made mostly mostly of iron Earth’s internal heat drives convection currents that push the mantle’s soft rocks upwards as it warms and downwards as it cools 13 245 M 286 286 M Permian Triassic 208 M 144 M Jurassic Cretaceous Present 14 Plate Plate Tectonics As mantle moves, it drags large plates of crust crust Earth’s surface consists of about 15 tectonic tectonic plates, most including most combination combination of continent and ocean Move roughly 2-15cm per year hl Large scale, gradual upward and downward downward movement of the lithosphere, including sudden horizontal displacements, occurs along fault lines displacements, 15 Red dots represent global distribution of volcanoes 16 Why & How are the plates moving? Wh 17 Systems Planet’s environment consists of complex Pl network network of interlinked systems, e.g. ecological webs, interaction of living i species species with surrounding landscapes, bi biogeochemical cycles Network of relationships among parts that interact interact and influence one another Feedback loops 18 Positive and Negative Feedback Feedback Loops Feedback Loop circular process Positive Feedback Loop change becomes more pronounced Negative Feedback Loop change is reduced or inhibited 19 Positive Positive Feedback (leading (leading to divergent behaviour) behaviour) Fig. 4-9A explosion No intermediate situation intermediate situation start blocking 20 Positive Positive feedback just means the the system is changing In everyday language we may use “positive” feedback to describe something “good” that has happened, i.e. something i.e. somethin “positive.” “positive.” There is no “good” or “bad” when we are “b speaking of positive feedback in systems. There is just change! 21 Examples of + feedback Exponential growth in human population Disease epidemics out of control out of control expansion expansion Cancer } Bankruptcy Economic depressions Erosion } inescapable spiraling down 22 Negative Negative Feedback (change is reduced leading to stability) Fig 4-9B 23 Examples of - feedback: Thermostats Cruise control Our body’s temperature (at least until we suffer suffer heat stroke or hypothermia) 24 Most systems in nature involve negative feedback feedback loops since enhances stability in the the long run, and only systems that are stable stable will persist Positive feedback loops can alter systems substantially substantially Rare in nature But common in systems altered by But human human impacts 25 Energy Energy Capacity or ability to do work Flows through ecosystems Why do organisms need energy? Thermodynamics Rules by which energy is transformed from one state to another. 26 First Law of Thermodynamics First Conservation of Energy (p.131-132) (p.131- Energy cannot be created created or destroyed Energy can be changed from one chan form to another 27 Second Second Law of Thermodynamics Thermodynamics When energy is changed from one form to another, some is degraded into heat Heat is a less usable form of energy Increases entropy (disorder) in the universe Everything in the universe tends to fall apart, slow down, disperse: becoming more disorganized, disorganized, unless we continually supply energy (e.g. gas for the car, cleaning up your room) room) 28 ...
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This note was uploaded on 04/04/2012 for the course ENV 200 taught by Professor Karening during the Spring '11 term at University of Toronto- Toronto.

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