Our Changing Environment El Nino, Ozone, and Climate
Our Changing Environment El Nino, Ozone, and Climate ATOC 1060
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ATOC 1060002 OUR CHANGING ENVIRONMNET Class 6 Chapters 23 Objectives of today s class a External forcing the response of daisyworld to increasing solar luminosity chapter 2 b Global energy balance Chapter 3 Previous cl 55 Feedback of daisy coverage on T Avevage ems elllpemkuve 4 Dalsy coverage 4 an ar rage 5 ace Negative couphng gmpgyg mre m Copyright 2004 Pearson Prenuce Hau nc Fig 27a Explicitly add albedo effect Daisy Daisyworld Avefrage coverage albedo sur ace temperature Average surface temperature Daisy coverage Cupyngm 2004 Pearsan Prenime HaH ms Flg 28 Averaqu w um mmpcmturr wage Surface Temp Daisy ugSurface Temp Daisy coverage l covera e g Dalsy coverag umumResponding to T changes Dz 5y mum age 4 Mmmm39n Muxvmum Flg 29 Average wrfuu cmpcrn39urc a w Cupyngm 2001 Pearson Prenuce Ham nc Equilibrium state in Daisyworld P1 and P2 are the two equilibrium states of the system mm coxmag AvPrrqa wwncp 39Fmp mlum a m hnqahk mu 1 Mm Copyrigm 2uozl Pearson Premlce Hatl me Stable amp unstable states Average Daisy P1 surface Stable temperature coverage Average Dals P2 surface Unstable temperature coverage CnpyrrghVQEUOA Pearson Premme Ha l nr Today a External forcing the response of daisyworld to increasing solar luminosity Equilibrium state perturbation or forcing how the system respond Idealized daisyworld daisy coverage amp planet temperature Complex system The Earth system Response of daisyworld coupling to forcing Fig 212 Avuragc surface Lumpuratum me an mcrcasc m solar ummosrry Without an Increase m solar ummosity Daisy coverage Copy gm 2004 Pearson Wermce Ha lr nc Response of equilibrium states to forcing My w 94 4 ArmAnAn ne atiVe Feedback factor fiA q i ATO Longer time span for daisies Fig 2 copyngmg 2qu Peavson Prentlce Han Inc The lessons of daisyworld Climate system not just passive there are feedback loops negative feedback loop gt damp external forcing Daisyworld increase life span Real climate system negative feedback loops gt stabilize the system Self regulating Coupling in the system self regulates Gaia hypothesis Even a stable system persistent forcing could become unstable Summary of chapter 2 Systems components couplings feedback loops Positive feedback loop amplify perturbation or forcing Negative feedback loop damp Equilibrium states stable amp unstable Daisyworld climate system negative feedback Loop gt self regulating naturally b Global energy balance the greenhouse effect chap 3 r Venus460C Cupyngmeeaofsa an fgmne Hall lnc A Mars55C Why is Venus so hot Why is Mars so cold Why is Earth just right Distance from the Sun Venus close Earth rnidd1e Mars far Greenhouse effects Earth no greenhouse 33C colder Electromagnetic radiation Selfpropagating electtic and magnetic Wave Wave 5 Bed 6 4 Wavelength k p gt Time t Time t At quot Fig 32 Speed 0 3007 OOOkms 3 gtlt lob39ms A Wavelength the distance between two adjacent crests l frequency at a xed point a given number of cresw passed by in 1 second P period the time it takes the electromagnetic Waves to travel for one Wavelength A c X P c 1 WavedengtlFspeed x periodq eed e lcy p 7 Period 2 31 f equency Photons and photon energy Electromagnetic waves also behave more like a stream of particles waveparticle duality A single particle or pulse of electromagnetic radiation is referred to as a photon Energy E of a photon is r 663 X 10 54Joule seconds I E 7211 h x speed 300000kms Energy wavelength The electromagnetic spectrum 1m 1061771 109nm Wavelength mm 1 102 103 10 105 w t t lt szlbte erays chrowaves and w 39 climate 3 Gamma Radio waves lays t A mm o 1 1 u Viclul Gveen o angc Fig 33 B ue Veuuw m 2ultv4 Pearson Pverwce Ha l m 40 IR 10 UVV15ib1e light Flux F the amount of energy that passes through a given perpendicular area per unit time Wm2 J1 F mcommg hgm Fig 34 Pap r mangetnmccnwghgm n I Cupyrlgm 2004 Pearsuu Prentlce Hall Inc The inverse square law Fig 35 Cupyrlgm 2004 Pumva Premium Ham mu Temperature measure of the internal heat energy of a substance TABLE 31 Boiling Point Temperature Scale Freezing Point at sea level Fahrenheit 32 212O Celsius 00 1000 sea level Kelvin absolute 27315 3731Fsessure Copyright 2004 Pearson Prentice Hall Inc TquotF 32 18 T F T C X 18 32 T C TK TquotC 27315 ATOC 1060002 OUR CHANGING ENVIRONMENT Class 17 Chp 56 Objectives of Today s Class 1 Lab demo westward intensi cation deep water formation salinity effect 2 Thermohaline circulation conveyor belt 3 Ocean circulation and climate 4 Modeling the AtmosphereOcean System 1 Lab Demo Westward intensification Deep water formation salinity effect 3 W 1 Fig 542 Copy ghx 2004 Pearson Premise Hall mo Salinity efvfectngorth Atlawpticw1009wm Fig 514 Copyright 2004 Pearson Prentice Hall lnc High T High S V nddriven relatively Mediterranean Sea Sha W deep coean circulation reality more water complex 3 Ocean circulation and climate NH poleward heat transport Ocean dominates ow latitude Atmosphere dominates middlehigh latitude Total 4 x Atmosphere A 2 H9545 Northward heat transport 1015 W oZ l 0 39 39 SOLN 39 39 oogu 39 39 90 N heat reserVIor longLJ39Ieam climate nutrient cycling C02 storage 4 Modeling atmosphereocean climate Why numerical models Predict future s climate We need model of the system CO2 buildup a INPUT Winds pressure rain clouds Energy transfers PROCESS Copyright 2004 Pearson Prentice Hall Inc Climate gt OUTPUT SimplFeig gystem model for CO2 buildup and Climate conceptual model quaitative Considering Icealbedo feedback in the system important Increased temperature reduce ice cover reduce albedo increase temperature Positive feedback loop Quantitatively by how much Quantification important gt which process dominates gt what will happengt tell the future How much temperature change will cause how much seaice change An empirical or a statistical model based on observational data rather than physical principles Example Sea ice edge advances or retreats 100km for every 1 C temperature change ComplicationFeedback for ice Oceanatmosphere interactions i i ALBEDO GREEN HOUSE EFFECT T TEMPERATURE 4 OCEAN TO ATMOSPHERE HEAT FLUX ICE COVER CLOUD COVER 7 ALBEDO Fig 62 Just which temperature increasing Copyright 2004 Pearson Prentice Hall Inc process dominates Is the A numerical model based on physics Takes into account all processes amp feedback loops that we know If it produces realistic present climate gt predict future by adjusting input For example we can increase CO2 concentration and see how the system responds Modeling the climate system Includes the Atmosphere Land Oceans Ice and Biosphere a 1Dimensional radiativeconvective 223mg c I i m m o d e I Stratus Clouds Evaporaiive and H922 Ccuimtzus Cirrus Clouds Cu 5 Precipitation b 2 D I Evaporamn snow cover Atmosphere Imensmna Land odel I I I n e n e y I a n c e Precipitation snag d g V Runoff amp Evaporation 0 s g climate model 39 Ice cloud amp sea Ice Ocean Heat amp Salinity lt change with latitude verticallatitude Current Temperature and Salinity Vegetation Reflectivity Topography and Land Use Realistic Geography Ocean GCM c 3Dimensional General circulation models realistic topograph Vertical Overturning Bonom Topography Ocean Model Layers Global climate models An ocean general circulation model OGCM An atmosphere general circulation model AGCM Land surface model Sea ice model Biology National Center for Atmospheric Research NCAR Community Climate System Model CCSM A series of equations solved using super computers Earth simulator in Japan fastest Using models for climate experiments 1 Understand processes such as effects of cloud cover vegetation topography etc on climate system 2 Paleoclimate modeling use previous landocean distribution 3 Weather forecasting using numerical models 4 Climate change CO2 increase double C02 etc more later Climate change experiments a Equilibrium Climate Change Experiments Hold the cloud cover constant four times the present CO2 concentration to see how climate system responds after the system reaches equilibrium state Results in 1970s 4 C increase in global temperature with variable cloud cover 4 C increase with double C02 Climate change experiments b Transient Climate Experiments Start the model at the present or some point in the past and then run it forward to assess how the climate changes with time Input data that indicate how the greenhouse forcing will change with time Results atmospherequickly oceanslowly Timescales weeks in atmosphere seasons for land surface amp upper ocean hundreds of years for deep ocean ume 01502 common 7 quadruphug approach 39 1 per year 5 CO2 ru n 5 addwlluua wamnug double In S g A 70years E g 3 7 M a 2 7 g gt adcmora wavrmg use a simp e 1 7 Tm Nansen 0 male CGWWWGHL lom g 72x Ocean model 1 response atabwzed a 2 x COZ MK 3 a c c inate sensilwity J Using OGC 1 LHuBquO doublxrg wayeav cog nc39aase sVabw za on av 9 gt4 arm 4 x 02 50 100 150 200 250 300 400 450 5 0 Fig 65 Y ear Copyngm 2004 Pearson Prermce Hau Inc Results from 10 global Climate models Global averaged temperature change relative to the mean of 19611990 greenhouse gas forcing Models blue lines Observation black line E oquot w 49 f t ta 9 9 y 9 rs w phv ir L I Differencesuncertainties g l 1 l 3 er tamp e m Copyrlghl 2004 Pearson Premlce Hall lnc Global averaged Precipitation change relative to the mean of 19611990 Agreementsphysics Differencesuncertainties S greenhouse gas forcing n N MMquot e e r Greenhouse gas aerosol forcing e r e ewm Copyright 2004 Peavsun Prenuoe Han Inc ATOC 1060002 OUR CHANGING ENVIRONMENT Class 21 Chp 15 Objectives of Today s Class Shortterm climate variability 1 Introduction 2 The Holocene Previous classes longterm changes in climate Earth history over 46 by Influence of solar luminosity 30 less High atmospheric CO2 ampCH4 warm Earth when it was just formed Over the Earth s 46 by history 5 main glaciations 1 Huronian glaciation 23by ago 2 Late Proterozoic 600800my ago tillite dropstone glacial striation 3Late Ordovician 440my ago 4PermoCarboniferous 286my ago 5Pleistocene 18my fossil records oxygen isotope Atmospheric CO2 concentration mainly adjust climate change Sh e 39 mm Prvmin Hall Inc warmH umpnm m InsetMovie A showing the process of plucking Inset Movie 8 showing the formation of the terminal moraine IE 93 Today Shortterm climate variability Key questions How can we document climate changes that occur over shorter time periods What causes climate change on short time scales Where in the climate system do we look for processes that might cause climate variability on the time scale of years to decades 1 Introduction Short time scales changes on a hundredtoa thousand year amp variability on interannualtodecadal time scales Purpose gt a illustrate how the Earth system components interact b provide background for discussion of global warming We have seen importance of CO2 on regulating longterm climate change over the Earth s history Possible impact of humaninduced increased CO2 on future climate Global warming In the context of variability in the climate system that occurs naturally over these short time frames 10000 years ago Duration Era Pemd EDOCh Glaciations in millions M39H39Ons f fyears years ago Quaterna Pleistocene 001 101 W Slfogg ge glaciations gg 51 o 6 a Miocene 185 238 N E Oligocene 99 g 5 347 Equot 39 Eocene 21 1 43 Paleocene 102 a Last major continental glaciation maximum extent 21000 years ago Holocene the last glacial retreat 10000yrs ago to present Warm 2100 rs J a 6 C 12 5 160 7 5 5IO 7 77 25 9 The Holocene epoch f fiE W X1000yrs shortscale variability Cold Warm Have to take into accobunt 6 Cale Human impact Many g I Cold significant changes during 2 0 1395 1 0 3 g Holocene smaller than ff X 3k1000yrs those we project might occur in the future c m 15 C l l 0 1000 1300 1600 1900 Year AD 39Hg154 Anomaly 0 relative to 1961 to 1990 Human increase CO2 last 200yrs 05 7 How much it is due to natural variability and how much it is due to global warming l 00 V m Broad agreement with hermometers Anthropogenic greenhouse 1n I l l gage l l l 1860 1880 1900 1920 1940 1960 1980 2000 Fig 151 Year d Copyright 2004 Pearson Prentice Hall inc Climate change and variability Climate an assemblage of weather conditions experienced at a location over some reference time frame WMO 30yr averaging interval describe climate Climate variability the fluctuations that take place within that interval Climate change difference in the average conditions or in the pattern of variability between two time spans Cooling or warming wetter or drier gt trends fig 151d actually there is no normal climate Proxy climate data Direct measurements recent To extend the record backwar gt proxy data Inferred from other evidence Sedimentary rocks on land I 3 Cores drilled in sea floor gt E i J I Erequot Fossils in sediments gt physical 2 Yegrggp30 5 quot 0 environment organisms lived Warm Cooling g Uniformitarianism Assume Fossil plants animals lived U 115 C In same environment as those 8 1 1 0 1000 1300 160 1900 that exust today YearAp c N r r 7 w Fig151b For the past 10000 years we make use of other types of evidence gt ice cores particularly for earlier part gt paleoclimate past climate reconstruction Palynology study of pollen and organic micro fOSSiIS pollen grains are preserved in lake sediments amp peat bogs etc Core drilling divide into segments going back through time extract pollen from each layer reconstruct plant assemblages lived there then use present day distribution of those assemblages to place constrains on what the environment was like in the past 3000035000 yrs Dendrochronology a method of dating trees by counting their annual growth rings cross section rings each ring one year tree age width of each ring indicates amount of growth that year related to temperature and moisture availability 5500 years California 2 The Holocene Assembling Proxy data around the world gt the Holocene displays a considerable climate change and variability It appears that Middlehigh latitudes a dominance temperature change Tropicssubtropics greater changes in moisture availability gtResult partly from orbital effects that enhance seasonality amp continentality directly affect temperature regime and partly from resulting circulation change eg monsoon affects rainfall Central Greenland Change in Oxygen 18 130 Western Tropical North South Eastern Deuterium Figue 1 Difficult to determine local or global scale changes Consistent records gt some locations but not others magnitudes are different in different locations We tend to discuss global scale changes remember that there are large regional differences Small mean global temperature gt associated with relatively large changes in physical environment Mean temperatures at the peak of last glaciation were 56 C colder than the 20th century mean 800years ago Vikings Greenland 05C warmer than today gt double CO2 21st century 154 C warmer bigger than any natural climate change that occurred in the Holocene 10000yrs ATOC 1060 Review guide for exam 1 NOTE Two copies ofthe textbook are available as reserve material in the Math Physics Library in Duane one oor up from the classroom Exam 1 will cover lectures 112 HW1 and HW2 and the corresponding chapters of the textbook that are covered by the lectures We will not test the content of Lecture 11 which is the guest lecture For lecture 12 exam 1 will cover the Coriolis effect but will NOT include the concepts of geostrophy and geostrophic wind The exam questions are multiple choices 1 Concepts and laws Understand the concepts and laws You are not required to memorize the exact words and numerical values of the concepts we have covered but you are required to fully understand them For example Greenhouse effect global warming glacial and interglacial periods buoyancy positive buoyancy neutral buoyancy negative buoyancy ITCZ Hadley cell the V en s law StefanBoltzmann law etc 2 Interpretation of charts gures Understand the gures You should understand and be able to interpret gures and charts 9 Processes You should be able to explain some physical processes For example how are Hadley Cells formed How are the northeasterly and southeasterly trades are formed A Example questions Below are some example questions The exam however will cover all materials in lectures 11 2 except for the guest lecture as mentioned above and is not limited to the following questions 1 What are greenhouse gases 2 What is greenhouse effect 3 What is global warming 4 What are the four fundamental components ofthe Earth system 5 What are the three major global environmental changes that are occurring today hint global warming ozone depletion tropical deforestation 6 What do Figure 12 and Figure 13 tell us about C02 concentration 7 What does Figure 14 tell us about the Earth s temperature What is the relationship between the Earth s temperature and 002 concentration 8 What are the possible consequences ofglobal warming 9 What is the Antarctica ozone hole What are the possible consequences of ozone depletion 10To what two global environmental problems does tropical deforestation contribute hint decrease biodiversity and increase 002 therefore contribute to global warming 11 Why do we need to know global change in the past 12 What are glacial periods What are interglacial periods Mark the glacial and interglacial periods in Figure 19 ofthe textbook 13 Why is iridium a good indicator of impacts by extraterrestrial bodies 14 According to Figure 111 what is believed to occur at the K T boundary Why did dinosaurs disappear 15 What does the event at the K T boundary tell us about present day climate hint dramatic changes caused by external forcing can change the Earth s climate from one equilibrium state to another 16 How has solar luminosity changed during the past 46 billion years 17 What is the Gala hypothesis and what does it say about the importance oflife on this planet 18 What is system What are the components ofa system 19 What is positive coupling What is negative coupling 20 What is positive feedback loop What is negative feedback loop 21 What are equilibrium states What is stable equilibrium state What is unstable equilibrium state 22 Which one has higher albedo re ectivity fresh snow or grass see Table 2 1 23 Which one has higher albedo thick cloud or forest 24 Understand the feedback loops of daisyworld climate system Figure 210 and Figure 211 25 What are the three major factors that determine the Earth s surface temperature see lecture 8 26 The energy E of a photon of electromagnetic radiation is inversely proportional to its wavelength A LC A a where h is a constant called Planck s constant Which photons have higher energy UV or visible light 27 Which photons have higher energy visible light or infrared radiation IR hint UV has the shortest wavelength IR has the longest wavelength and visible light is in between Reference Figure 33 of the text book 28 How is electromagnetic radiation ux defined 29 What is the inversesquare law ofelectromagnetic radiation What does it tell us you re required to understand it but not required to remember the formula 30 How many temperature units or scales do we often use Hint Celsius Kelvin and Fahrenheit 31 What is V en s law Note you need to understand the law but not required to remember the formula 32 Why is the Sun s maximum radiation in the visible light range and the Earth s maximum radiation in the IR range 33 What is StefanBoltzmann law you are required to understand the law 34 According to StefanBoltzmann law which one has a higher energy ux the Sun or the Earth 35 Why does the Earth s atmosphere produce greenhouse effect hint strong absorber of IR radiation from the Earth s surface and part ofthe IR is emitted back to the Earth s surface 36 What are the three most abundant gases in Earth s atmosphere today Is any one ofthem greenhouse gas see Table 32 37 What are the important atmospheric greenhouse gases Table 33 38 Based on observational evidence what greenhouse gases are currently increasing in concentration in the Earth s atmosphere 39 How does atmospheric pressure vary with altitude increase or decrease 40 How does temperature vary with altitude in the Earth s atmosphere Figure 3 9 ofthe textbook 41 List the four layers ofthe Earth s atmosphere troposphere stratosphere mesosphere thermosphere 42 The ozone layer is located in which ofthe four layers mentioned above 43 What is convection What is latent heat 44 Why is the Earth s surface the heating source for the atmosphere 45 Why are H20 and 002 efficient greenhouse gases 46 Why aren t N2 and 02 greenhouse gases 47 How does clouds affect atmospheric radiation budget re ection of solar radiation and absorption of IR 48 Why are effects of clouds on Earth s radiation budget so complicated 49 Identify two positive feedback loops in Earth s climate system 50 Identify the negative feedback loop in Earth s climate system Why is Earth s climate stable despite the destabilizing positive feedbacks 51 How is the Hadley cell formed 52 How are the northeasterly trades and southeasterly trades are formed 53 How are the midlatitude westerly winds formed 54 What is the driving force for global atmospheric circulation see Figure 42 of the text book 55 How is the polar font zone formed ATOC 1060002 OUR CHANGING ENVIRONMENT Class 12 Chp 4 Objectives of Today s Class 1 Lab Demo Hadley circulation Without rotation Effects of rotationCoriolis force Global animation of water vapor and real earth videos of the lab experiments Lecture seasonal variability Lab experiments Hadley circulation without rotation Effect of rotation low rotational ratezonal winds high rotational rateinstabilities waves Global animation of satellite observed water vapor which will indicate atmospheric general circulation Videos will be shown after each lab experiment in order to better digest what you have seen in the experiment All these materials are designed to let the students better understand the important concepts covered in the lectures and to let them visualize the observed climate variability Summary lab experiments amp previous class Meridional circulation ITCZ Polar front Polar front zone Surface High High High Low High High High pressure pressure low pressure pressure pressure low pressure 9390 6390 3390 I 3390 6390 910 Northern Hemisphere Southern Hemisphere Latitudes F1g 47 Hadley Circulation Polar front Coriolis Effect Earth rotates fastest at equator slowest at poles Imagine a cannonball red due north from point A Cannonball starts with eastwards motion equal to rotation at equator B rotates slower so cannonball moves farther east than B Cannonball appears to be de ected to RIGHT Seen from space cannonball moves in a straight line Important Features Polar Front gt Polar easterhes Polarhlgh gt Midlatitude 600 4 P5313333 Hadley Cell Westerhes lVelsterlies 3O Subtropical high Subtropical High Weak winds 0 U Easterly Trades 0 Intertroplcalconvergence zone A Doldrums 30 Subtropical high lVesterlies Weak Winds 600 polarp aile l s I Pofr gh Fig 4 11 Copyright 2004 Pearson Prentice Hall Inc Midlatitude waves Actual surface ow is highly variable ITCZ is discontinuous Midlatitude westerlies are disrupted by passage of extratropical highs amp lows Extratropical Cyclones lows Form near polar front Winds spiral into low pressure Important for heat transport amp precipitation Upperlevel ow Vertical CrossSection L VOW H 10 7 300 mb 7 500 mb 4 PGF Low Dngll l Density 2 E PGF 7 800 mb Aquot COLD f quot WARM 1000 mb 90 N 60 N 30 N EQ Fig 412b Lines of constant pressure slope down from equator Pressure gradient Force PGF points poleward above surface 7 Strongest PGF at tropopause Geostrophic Flow Balance between PGF and Northern Hemisphere Coriolis force LOW Parallel to pressure llne Low pressure to left right of flow in NH SH Not very accurate c approximation near surfac friction Very good in upper atmosphere The stronger the PGF tighter the isobars the stronger the Vg HmH PRESSURE Pg Pressure Gradient Force C Coriolis Force VG Geostrophic Wind Fig 4 13 Jet Stream few 4 300 mb mb Isobars B B Constant 800 mb P A A ressure 0013 WARM 1000 mb 90 N 50 N 30 N EQ Fig 4120 0 Adding Coriolis Westerly geostrophic ow 0 Fastest ow in tightest isobars Jet Stream Seasonal variability December Solstice December 21 June Solstice June 21 Fig 415 1 September Equinox September 22 Copyright 2004 Pearson Prentice Hall Inc 391 cm am Pro le Seasonal variability atmospheric circulation June 21 December 21 Nunhem Hemisphele Poiur from I mm Suumem Hemisphere Hemisphere Copyvigma 2004 Pearson Prentice Haii Inc Fig 416 ATOC 1060001 OUR CHANGING ENVIRONMNET Class 2 Global Change Chapter 1 Objectives of today s class 1 The changing Earth an overview 2 Three major themes of the changing Earth Class website httpatoccoloradoeduwhanATOC1060 l Announcements Link to download acrobat Visit course website at httpatooooloradoeduwhanATOC1060 under ClassNews Grade Posting Permission Form under Syllabus in the website Turn in as soon as possible Register your iClieker 1 The changing Earth an overview Earth has always been changing significantly faster rate now than the past throughout most of its 46 billionyear history Causes for the faster change in recent decades human Q activities anthropogenic forcing Increased population amp high technologygt big impact 2 Human impact on the atmosphere forests mountains lakes rivers oceans global climate 7 v 2 47 Human impacts greenhouse gases Global climate the prevailing weather patterns of a planet or region overtime is being altered by the addition of green house gases to the atmosphere Greenhouse gases are gases that warm a planet s surface by Absorbing outgoing infrared radiation radiant heat and reradiating some of it back toward the surface This process is called the Greenh use e ect A natural physical process in all planetary atmosphere x V 0 Venus 302 carbon dioxide major compositipn Earth 150 302 much less On Earth most abundant anthropogenic greenhouse gases are302 Burning fossil fuel coal oil natural gas 0 remains of organis 39ns fossilized Deforestation trees cut down decay release 02 gt Global warming a warming ofEarth 5 due to an anthropogenic enhancement 6 Natural processes produceconsume 602 Volcanic emissions 10 CO2 Cycled back amp forth by living plants amp animals D002 abundance is controlled by a combination of natural and humaninduced processes 7 Human impact Ozone depletion Ozone layer a chemically distinct region within the stratosphere part of the earth s atmosphere Protect Earth s surface from the Sun s harmful ultraviolet UV radiation Antarctic ozone hole in recent decades a patch of extremely low ozone concentration is thought to be human origin freon can destroy ozone 8 Human impact deforestation Deforestation mainly in the tropics at a fast rate kill off many species of plants and animals decrease biodiversity the number of species present in a given area Meanwhile deforestation 39 atmospheric 302 Are these anthropogenic effects urgent problems Earth is altered by human activities currently at an unprecedented rate a Increased greenhouse gases gtglobal warming b Chlorinecontaining compounds freon gtozone depletion ozone hole c Tropical deforestation gtdecrease biodiversity releaseCOQ 10 2 Three major themes of the changing Earth a Global environmental issues What should we do about them global warming ozone depletion deforestation Intelligent decision requires scienti c knowledge politics science incomplete costly gt need to understand the problems Sea level increase Extreme climate events Webster et al 2005 Science Global warming amp Hurricane intensity b How to estimate and understand human impact gt Global change in the past Understand the past before humans came on the scene long short time scale changes Cores Drilling Program gt today we are in interglacial period in between glacial periods Understand the present climate With human in uence e The Earth system A system is a group of components that interact f Atmosphere The Earth Hydrosphere water system Biota all living organisms Solid Earth Fig 11 oftext book Schematic diagram of the Earth system showing interaction among is four components One goal understand how these components interact in w response to swam various internal amp He cncrq Wear Encqu y r r external 1n uences M 5 Summary 1 The changing Earth an overview Emphasis humaninduced changes a Global warming Increased greenhouse gases b Ozone depletion freon 0 Tropical deforestation 2 Three major themes a Global environmental issues b Climate in the past c The Earth system ATOC 1060002 OUR CHANGING ENVIRONMENT Class 18 Chp 6 Objectives of Today s Class 1 Global climate modeling experiments 2 Uncertainties Previous Modeling the climate system Includes the Atmosphere Land Oceans Ice and Biosphere a 1Dimensional radiativeconvective 223mg c I i m m o d e I Stratus Clouds Evaporaiive and H922 Ccuimtzus Cirrus Clouds OLI S P 39 t t39 b 2 D I EZ ZCFl glraa fg snow cover Atmosphere Imen5ona Land odel I I I a e n e y I a n c e Precipitation snag d g V Runoff amp Evaporation 0 s g climate model 39 Ice cloud amp sea Ice Ocean Heat amp Salinity lt change with latitude verticallatitude Current Temperature and Salinity Vegetation Reflectivity Topography and Land Use Realistic Geography Ocean GCM c 3Dimensional General circulation models realistic topograph Vertical Overturning Bonom Topography Ocean Model Layers 3D Global climate models An ocean general circulation model OGCM An atmosphere general circulation model AGCM Land surface model Sea ice model Biology National Center for Atmospheric Research NCAR Community Climate System Model CCSM A series of equations solved using super computers Earth simulator in Japan fastest 1 Using models for climate experiments 1 Understand processes such as effects of cloud cover vegetation topography etc on climate system 2 Paleoclimate modeling use previous landocean distribution 3 Weather forecasting using numerical models 4 Climate change CO2 increase double C02 etc more later Climate change experiments a Equilibrium Climate Change Experiments Hold the cloud cover constant four times the present CO2 concentration to see how climate system responds after the system reaches equilibrium state Results in 1970s 4 C increase in global temperature with variable cloud cover 4 C increase with double C02 Climate change experiments b Transient Climate Experiments Start the model at the present or some point in the past and then run it forward to assess how the climate changes with time Input data that indicate how the greenhouse forcing will change with time Results atmospherequickly oceanslowly Timescales weeks in atmosphere seasons for land surface amp upper ocean hundreds of years for deep ocean ume 01502 common 7 quadruphug approach 39 1 per year 5 CO2 ru n 5 addwlluua wamnug double In S g A 70years E g 3 7 M a 2 7 g gt adcmora wavrmg use a simp e 1 7 Tm Nansen 0 male CGWWWGHL lom g 72x Ocean model 1 response atabwzed a 2 x COZ MK 3 a c c inate sensilwity J Using OGC 1 LHuBquO doublxrg wayeav cog nc39aase sVabw za on av 9 gt4 arm 4 x 02 50 100 150 200 250 300 400 450 5 0 Fig 65 Y ear Copyngm 2004 Pearson Prermce Hau Inc 2 Climate models uncertainties Global climate models 3D exchanges of energy mass and momentum within the atmosphere and oceans between atmosphere ocean atmosphereland Govern equations physical laws Discrete grids resolution effective grid size of the model amp model time step Reasonable simulation of present climate NCAR CCSM warming El Nino etc But it does have uncertainties mostly due to resolution of the calculation Climate model Grids Calculation of equations using Computer on grid points Assume 50km Scales smaller than 50km Not RESOLVED by the model Parameterization Subgridscale processes Parameterization For example convection Different GCMs use different parameterization schemesgt different results Dependence on initial condition Temperature difference First decade of 21st century iii Exp1 19751395 Exp 5 7P7 IIE i iii iiii a on 7 rm 7 0 As it 20 s Cupyrighl 2004 Pearson Prenilce Halli inc Are the model results usable Although there Are uncertainties GCMs mostly agree all show global warming 10 different GCMsL v Dark line observed 9 9quot 9 9 x 7 Global mean temperature a Relative to the mea 19611990 Geenhouse gas f rcin 39 nof E9 f W 39 Geenhouse gas aeroso forcing M v rw WV Copyrighl 2004 Pearson Prenllce Hall inc Globai Precipitation for 10 G L MS wings m Geenhouse gas ing mm Geenhouse gas aeroso forcing WimpWA u vwimri l Copyright 2004 Peavson Premlce Halli inc ATOC 1060002 OUR CHANGING ENVIRONMNET Class 3 Global Change Chapter 1 Objectives of today s class Observations Global change on short time scales Announcements Grade Posting Permission Forrn Turn in as soon as possible httpatooooloradoeduwhanATOC 1060 Iolioker s registration info website under oliokers Previous class The changing Earth an overV1eW Emphasis humaninduced changes a Global warming Increased greenhouse gases b Ozone depletion freon c Tropical deforestation Three major themes a Global environmental issues b Climate in the past c The Earth system 1 Global change on short time scales Observations Three major global environmental changes occurring today a Global warming b Ozone depletion c Tropical deforestation a Evidence of global warming Global warming an increase in Earth s surface temperature caused by a combination of industrial and agricultural activities humaninduced forcing Greenhouse gases gt Enhance greenhouse effect gt First step measurement of greenhouse gases in the atmosphere 380 i 370 if 360 n 350 i 340 e 330 CO2 Concentration ppm 320 3101 The Keeling Curve Measurement of atmospheric 02 Seasonal change 56 ppm 1955 J i 1965 1975 1985 1995 2005 Capyrlght zuua Peavsuu Prentice HaH m Fig 12 Measurements ofatmosphenc carbon dioxide 602 at the top 6 of Manna Loa Volcano in Hawaii 5 chl ng cum 0 W 7 o Ice cores data N m 7 18001850 pioneer 1850present industriel E 0 man 1200 who who VUUI Copyrignx39zj 2cm Feavsun Fventme eat me Fig 13 Atmospheric 302 from ice cores on Antarctic amp from direct atmospheric measurement for the past 1000 years Other Greenhouse Gases In addition to 02 other greenhouse gases such as methane CH4nitrous oxide N20 and certain chloro uorocarbon compounds CFCS also called freon have also been increasing as a result of human activities We are certain that anthropogenic greenhouse gases are increasing Are the increased greenhouse gases causing global warming 8 gt temperature we mm the 1061 01990 average Deparm Observed changes in surface temperature GLOBAL 0 4 Observations atmosphereocean dif culties Signal real 7 approac 39 1 1 1 1 1 1 1 r 1 1 1 1 1 1560 1880 1900 1020 1940 1950 1980 2000 Year Copyrrgm 2004 Pearson Premrce HaH 1nc Fig 14 Change in global average surface temperature since 1861 Possible consequences of global warming Has it been changing our climate Concern Although debatable global warming gt extreme weather events say increase hurricane intensity Webster et al 2005 sea level rise 10 cm in the past century 10 Levitus et 211 2005 Global ocean heat content 1960 1980 2000 PACIFIC OCEAN u Hum quot In Illll u H Itnll 1960 1980 2000 Year b Observed Ozone Depletion 450 400 E Fig 15 Mean total ozone above 3 Halley BayAntaIctica dining Octobe A 350 E 300 3 a g 250 E 9 g 200 E B g 150i gt9 100 50 1 Dobson unit is equivalent to a 0001cm thick layer of pure ozone at the surface WHHHH HWHH o i 1950 1950 1970 1930 1990 2000 70m Year Copyright a9 2004 Pearson mm aH ms Cl 03 010 02 Chlorine Atomic chlorine monoxide Fig 16 Observed Ozone 03 and chlorine monoxide C NASA aircra September 1987 20m mnn 03 mm lal u ppm as am as 65 7m 72 saw lamude mo 7 52 tember 5x 9 99 7 September A waz Cupynght 2004 Pearson Prermue Hail mu Ozone depletion concern Far south Chile and New Zealand concerned Gradual decreasing of Ozone in midlatitude of both hemispheres maybe due to increased humaninduced CFCs Now Groundlevel CFCs decreasing ATOC 1060002 OUR CHANGING ENVIRONMENT Class 19 Chp 12 Objectives of Today s Class 1The longterm climate regulation 2The longterm climate record Previous class Are the model results usable Although there Are uncertainties GCMs mostly agree all show global warming 10 different GCMs Dark lines observed 9 a 3 a a a ms 19 g 9 quot4 39 Relative to the mean of 19611990 IMW Geenhouse gas gag f rcin 1quot c 5 Global mean temperature f f f mm mm mm is 39 Geenhouse gas aeroso forcing Cupynghl 2504 Pearson Prenllce Hall Inc 1 Longterm climate regulation Faint Young Sun paradox present 1 l l l F3 m l l o 00 l l Solar luminosity relative to today 46 by 390 Solar evolution model 0 l l l 30A less 07 4 3 g 1 solar flux Fig 112 TimebyrBP camgnm am Penman r llll leg Hall inn Below freezing 19by ago gt contradict geological evidence liquid water was present 38by ago The earth was warmer than predicted by the fain young sun Possible solutions i Lower planetary albedo in the past 0 ii Additional heat sources besides the Sun geothermal heat small iiiLarger greenhouse effect iii Larger greenhouse effects most likely C02ampCH4 Young Earth Higher C02 Impact Degassing carbonate rocks Smaller Continents gt reduce carbonate rocks storage reduce silicate rocks weatheringgtincrease atmospheric C02 Silicate weathering example remove atmosphere C02 CaSiO3 2H2CO3 gt Ca2 2HCO3 39Si02HZO CO2 dissolve in raindrops acid Silicate weathering process proportional to temperature Models Methane 1000ppm 600times of today 16ppm 3823by ago Archean Eon when 02 l evels low Favor production of CH4 by methanogens A pink sky during Archean The Earth blue sky The Mar larger particles Scattering blue lights 02N2 Archean CH4 amp C02 polymerizegt bigger longchainsgtscattering orangered light A pink sky during Archean The Earth blue sky The Mars pink red Scattering blue lights 02N2 Archean CH4 amp C02 polymerizegt bigger longchains haze gt scattering orangered light Climate regulation by the anti greenhouse effect Was the Earth getting hotter and hotter until no life could survive NO Antigreenhouse effect CH4 and haze strong absorbers of visible red light and nearinfrared gt reradiating back into space without reaching the Earth s surface gt cools Earth s surface If haze layer too thick gt The Earth too cold gt CH4 producing bacterial died off gt recluce CH4 gt thinner haze layer gt increase Temprature Regulating the climate in Archean Era 2 The longterm climate record Up to now focus on very early Earth amp processes may have contributed to climate stabilization Geological indicatorsgtpaleoclimate past climate complex gt longterm warmth periods amp short intense cold periods there may have been Snowball Earth episodes gt suggesting other factors may affect climate as well Paleoclimategeological indicators Recent Earth history millions yrs estimate ocean temperatures by oxygen isotopes in carbonate sediments fr 5 sglaeleepsea cores 1CaCO3 gt 160 and 13 the colder the water the more 180 to be incorporated by minerals Glacialinterglacial cycles in about 200my 2 540my fossil record species of plants and animals live in certain climates gt estimate local surface temperature Evidence of past glaciation Billionyear timescale Geologic deposit formed by glacial ice Debris when glaciers grind up surface rocksgtcarried by i i r glaciers amp dep 39 39 drin pileso fJ rubble moraines icesheet m i gquot j m m m a 91239 Rocks with long parallel scratches glacial striations moving glaciers drag other rocks across their surface r 39 r 7 39 quot a m Fig 127b b Copywth 200 Pearson mm Ham m Misplaced trunks of rock in otherwise finely laminated marine sediments Rocks Trapped In glacial lce carried quot to sea by 0 39D o 2 to w Dropstone C cwymmmm Paavsan mm Hall inc The longterm gl Geologists Earth s 26 l 800my c Imate Late history Proterozoic 5 main glaciation 123by periods Huronlan 4 286my PermoCarboniferous 5 18recent Pleistocene 393quot quot Mi lllll nl Hulaquot EON GLAClATlONS ERA Wears yeamag g cmozoxc es 8 M 186 c 11 PALEOZOlC 293 n Late Proteroz Neop ooooooo m 330 g aaaaaaaa ns 9 Mesopml 700 E c 2 g E m E L p eeeeeeeeeeee lC 900 Hum g g aaaaaaaa ns 2 lt u a LATE a z E I MlDDLE 400 u u lt EARLV 400 2 lt 3 am lt I 3 440my Late 9 o N a m 4 3 Cambnzn PRECAMBHlAN 23by ago derived by tillite amp dropstone First found in lake Huron N America gt Huronian glaciation Followed by 1by icefree conditions Why was there a glaciation Suppose CH4 was high in Late Archean 325by gt 02 rise around 23by due to biological activities photosynthesis gt eliminate CH4 gt cold Geological evidences agree with this How did the Earth s temperature rise again Silicate weathering decreases with decrease of temperature gt increase CO2 gt increase temperature Lowlatitude glaciation the snowball Earth The climate became cool once again Glaciation in the Late Proterozoic 800600 my ago Rising CO2 gt increase Temperaturegt increase silicate weathering gt decrease CO2 gt cool the temperature Geological evidence tillites glacial striations dropstone were found on 6 of the 7 present day continents except Antarctica largely buried by ice gt Snowball Earth The continents reconstruction at Late proterozoic N Near equator bags M 96 laciated from one w i6 9 W a nd toanother 5 RA L SIBERIA m f g ANTARCTC 395 f ILL Spreading ridge V2 Subduction zone Fig 1210 Today tropical glaciation confined to high mountains Example Andes mountains in S America above 5km Geologists convinced Late proterozoic glaciation is real all data ATOC 1060002 OUR CHANGING ENVIRONMENT Class 26 Chp 16 Objectives of Today s Class Global warming 1 AOGCM predictions of global warming amp longterm climate warming 2 Changes in sea level and ocean circulation 3 Effects on ecosystems Previous class IPCC Difference CO2 emission scenarios 1D model prediction over next century Best case 2 C worst 5 C 002 concentration ppm 002 emissions G C Estimated CO2 emissionx I d quot 1300 1200 H 1100 i 1000 900 s 800 i 700 600 s 500 400 Year a l 39 I 39 I 39 i 39 1 39 2000 2020 2040 2060 2080 2100 i i I i i I 1980 2000 2020 2040 2060 2080 2100 Year bi indicalors a m human In uence on m atmoipmra during me Industrial Era 1D model too simple 15 Overlooks other factors 3305 de m E 220 05 Radiative forcing by 8 gimme Mmem ran my other trace gases Memana cm Wm Amspnm com 2 c R u man mu 39suo ism is Giomi aimusahevm concenmhonn 039 three men rmer Flg 16394 greenhoussaas s Copyright 2004 Pearson Prentice HaH inc 1 AOGCM predictions of global warming IPCC estimated CO2 concentration in next century Also estimated 1300 CH4 N O 892 1000 90039 800 700 600 Warming cooling In accordance with the CO2 estimation fossil fuel burning 800 deforestation Year agriculturepopulation Fig 16b CO2 concentration ppm i I l i I I 1980 2000 2020 2040 2060 2080 2100 Most pessimistic case 16d CH4a factor of 2 N2050 To predict how much the increased trace gases affect future climate global warming precipitation etc gt 3dimensional global climate models Atmosphereoceangeneral circulation models AOGCMs Recall atmosphere heat capacity ltlt ocean ocean acts as a brake for how fast atmosphere can warm However chapter 6 after atmosphere CO2 stops increasing global temperature still increases for quite some time see next figure 5 H20quot co mmon 7 aming approach 39 1 er ear A Using OGCM c02 run39 aumuuuaiwammg double in g A 70years E E 3 M a 2 7 g gt adcmorai wavrmg Using a simp i Tm iransieni cw mate camvmmem lom g 72x 7 Ocean model i rem summed ar 2 x coZ 3 5 0 ciinate sensitivity J Current rate A 7 Mom V CO 7 a 5 05lyr other W9 m izavionav iramfliniegf 1 Iquot 39 260 2amp0 3 50 450 450 5 o 50 o 150 Fig 65 lecture 17 YEW Copyrignm 2004 Pearson Prentice Han Inc Iemperature change m Climate model prediction warming trend in next century 2100 range 14 58 C al Ears shcwthe rangein 2100 Pmduced by savera Wade s 2000 2320 2040 2060 21 e 1 Fi 1 66 9 4a Cupynght rkbuA Pearsun Prennce HaH Inc Longterm climate warming If we continue to burn the fossil fuel amp deforestation at the present rate gt warming longer Assume most fossil fuel reserve consumed in 400years Assume deforestation continue until 30 world forest remains Model estimate CO2 2100ppm in yr 2300 8 x preindustry Temperature45135C 2200 2000 1800 E 1600 r 1400 1200 1000 Atmospheric 002 pp 0 O O 4gt m C O O O 200 Business as usual 0 1800 Ilxll1 2200 2600 3000 3400 3800 4200 4600 5000 Box fig16 2 a Year 280ppm yr 1800 E 2000 Uptake by the oceans amp g 1600 8 Dissolution of sea floor sediments 0 1200 L 39 W th 39 f b t k a 800 ea eringo car onaeroc s 1n Silicate weathering E 400 E O Ii 1 x 10000 100000 1000000 1 00m y Year Mesozmc warm 010C warmer Pleistocene glacier56C colder 2 Changes in sea level amp ocean circulation l l l l l Sea level has increased by 12cm012m 4 V since 1880 7cm thermal expansion 5cm melting of mountain glacie Alp R Arvin 39 Global sealevel rise cm l I l l l 80 1900 1920 1940 l960 1980 2000 Fig 167 Year Ccpyrighl o 2904 Pearson Prentice Hall inc Future sea level rise Polar ice caps over the continents Greenland amp Antarctica Greenland 67m sea level most likely melts extends to lower latitude observations melting in fast rate Antarctic ice sheet 6070m sea level high latitude East Antarctic increased snowfall due to global warming may thicken the ice sheet contains most water The west Antarctic ice sheet 56m sea level may melt and contribute to global sea level rise Sea level rise ml Projections of future sealevel rise Include thermal expansion mountain glaciers Pose problems Gulf coast of N America Bangladesh islands in S Pacific amp Indian Oceans n5 00 1000 l l l l 206D 2070 2030 2090 739 quot C9 l l l l 2000 2010 2020 2030 2040 2050 2100 Fig 169 Veer 009mm 0 2mm Pamsuu mm mm lm IPCC predicted temperature and sea level change by melting Greenland lce sheet Global sea level change cm 600 500 400 300 200 100 null llnl xlm lnyln l l l Sea level rise 6 meters 13 Florida submerged Distant future 7880m 20 continentquot Will be submerged lll llllllllllll l l lll 0 2000 I 2400 2600 392000 3000 Year AD 2200 Fia 1610 Changes in thermohaline circulation aGoba warming gt enhanced hydrological cycle rainfal snowfall freshen North Atlantic Ocean gt reduce deep water formation gt weaken global thermohaline circulation bGreenland ice sheet melting Climate models not consistent 3 Effects on ecosystems a Increased CO2 concentration gt can increase plant growth rate efficient use of water during photosynthesis Complicated depends on water availability amp plant species For example corn sugarcane etc can effectively complete photosynthesis under low CO2 won t be affected much b Changes in speciation within forests temperature moisture soil etc Prediction of Species composition In Minnesota forests Under double CO2 conditions Other concerns Tropical Insects gt spreads to midlatitudes gtaffects agriculture Tropical diseases malariar31O spreads to midlatitudes Fishery Clays 500 Hod we er 39 Other 7 Basswood A 400 e g 7 Other 3 Pine Birch 3 300 V y B E s g 200 e 5 Maple 100 Aspen 0 l u I I 1750 1850 1950 2050 21507 2250 I Warming Greenhouse climate 3 Sands 500 Sandy soquot 400 Can not hold much wat r E 300 E g g 200 A E A l 1850 I 1950 2050 2150 2250 I Warming I Greenhouse climate 0 ATOC 1060002 OUR CHANGING ENVIRONMNET Class 4 Chapter 1 Objectives of today s class a Global change on short time scales continue bGlobal change on long time scales httpatoccoloradoeduwhanATOC1060 Announcement 21 Grade Posting Permission Form b HWl begins today Download from website httpatoccoloradoeduwhanATOC 1060 Previous class 1 Iglolbal warmin ee 111g v vul w J E 307 W E0 L r 280 mu 18001850 pio eer 18 resent industria m t t t t t t t x cm mm an Mnn man man may VMr capyvgnmmm rman men we mu m Fig 13 Atmospheric 302 from me cores on Antarctic amp rom direct atmospheric measurement for the past 1000 years I i i i GLOBAL Observations atmosphereocean dif culties gt2 Signalreal SE 353 F is 00 2 m39 g m 5 3E 04 a as 39 39 r approach 1 w i w w w x 1800 1920 1940 1960 1980 2000 Year Copyv ghl 2004 Peavson Prentice Hau mo Fig 14 Change in global average surface temperature since 1861 Schematic diagram to demonstrate the trend Temperature A l 16C Warming trend V 2005 5 2 Ozone depletion 03439 02 12007 i I I 3000 Chlorine E T 7 E Atomic chlorine monoxide 2000 600 E lt J 8 1000 g 5 5 7 s O 22 64 66quot 68 70quot 72quot y Flg 16 Observed Ozone 03 and South 39atitude chlorine monoxide ClO NASA aircraft September 1987 3Today s class Deforestation and loss of biodiversity Since 10000 years ago humans farmed gt alter land surface Tropical deforestation rate l 8 per year recently Forest Cover 70 055 of forest cover 4U Thaiand 20 thpplnes n 1 1 1900 1920 1940 1960 1980 2000 Figure b a Deforestation gt lost plant species gt lost of animals and microorganisms that live there New species may replace them but normally the number of species decreases gt reduce biodiversity Which changes should concern us the most Ozone depletion gt skin cancer immediate concern Global warming gt sea level increase extreme weather immediate concern Deforestation gt lost of speciesgt lost of medicines ghting cancel and other diseases but not as immediate Deforestation however increases C02 gt global warming Recovering timescale loss of species takes the longest time to recover Maybe the most important 10 Global change on long time scales a Past global change glacialinterglacial cycles b Mass extinction c Changes in solar luminosity Durauon V Minions or Era Fenod Epoch elaclauons 11mg years age nuaemaw 333 2323 lg zGlacialinterglacial E 35 7 jaicycles 25milli0n10000 g Eocsna 2 Pa39e mene 392 65 iMass extinction 5 millions Cretaceous 7e olaI luminosity all 45 O 2 Billion years g 144 g Geologwal w 2 J 52 39 mm Tlmescales Eon Era T quotW 5 Perlod epoch ll copyngm 2004 Pearson Pvenuoe Han Inc Global change in the past amp present Past before human intervention What geological period we are currently at Glacialinterglacial cycles 25 million10000 years agoPliocene and Pleistocene epochs Mass distinction between the Cretaceous and Tertiary periods65 million years ago Solar luminosity 45 billion years Earth history Glacialinterglacial cycles C02 Temperature change skaJ wN Fig 19 Icecore record at Vostok Antarctica Why does the C02 and CH4 increases Not human induced at that time Deep ocean circulation gt 302 COncentl ation gtClimate change gt ocean circulation gtA system in which components are tightly coupled System approach Mass Extinction Iridium and the KT Boundary Dinosaurs lived 150 million years in mesozoic era Fellmy WM Ended 65 million Years ago Otherszdi dghmw Fig111 Changes in Solar Luminosity 10 9 8 0 O 389 B 25va bioEE 50m 07 Faint young Sun paradox earlier earth cold because of low luminosity of the Sun The Gaia Hypothesis life maintains climate stability Photosynthesis consume C02 producing organic Matter Earlier time more C02 Selfregulating System stable gt Earth System Chapter 1 Summary Modern global environmental issues Past global change Behavior of Earth s systems
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