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Climate Change: The Move to Action (AOSS 480 // NRE 501) Richard B. Rood 734-647-3530 2525 Space Research Building (North Campus) [email protected] http://aoss.engin.umich.edu./people/rbrood Winter 2008 January 29, 2008 Class News • A ctools site for all – AOSS 480 001 W08 • This is the official repository for lectures • Email [email protected] • Class Web Site and Wiki – Climate Change: The Move to Action – Winter 2008 Term • Wunderground Climate Page – Posted Introduction of the New Rough Guide – My recent series on models Readings on Local Servers • Assigned – Stott: External Forcings of 20th Century Climate – Andronova: Anthropogenic Forcing of 20th Century Climate • Of Interest – – – – NASA Langley: Aerosol Fact Sheet Terra Mission: Aerosol Fact Sheet NASA SVS: Aerosols over South Asia (1) NASA SVS: Aerosols over South Asia (2) Lectures coming up • http://www.snre.umich.edu/events • MLK Day Keynote Speaker: Dr. Warren Washington // Climate Modeling // Tuesday, February 5, 2008 - 4:00pm to 5:30pm //Location: Stamps Auditorium, North Campus, Charles R. Walgreen, Jr. Drama Center • Erb Speaker Series: Jim Nixon, Alcoa, "Challenges for an Energy Intensive Business in a Carbon Constrained World" Tuesday, February 5, 2008 - 5:00pm to 6:30pm Ross School, Wyly 0750 Outline of Lecture • Let’s talk about next Tuesday a bit. – Warren Washington will be with us. • • • • Radiative Balance of the Earth Feedbacks: Responses to global warming Aerosols Introduction to Models The Sun heats the Earth which cools to space SOLAR TERRESTRIAL WATER (& BIO) TERRESTRIAL ICE LAND & BIO Gives us an atmosphere that looks like this (near the surface) COLDEST WARMEST WINTER POLE SURFACE SUMMER POLE How does the climate respond? • There is motion in the atmosphere and ocean. • Water circulates between ocean and land and air. – Between ice and liquid and vapor • There is a dynamic balance of water and temperature. If we change something what happens to this balance? • FEEDBACKS .... – The idea that one thing causes a second thing to happen. • That second thing then does something to the first thing – It damps it, negative feedback – It amplifies it, positive feedback The Earth System: Feedbacks 1 Infrared Proportional to Temperature Top of Atmosphere / Edge of Space Assume that greenhouse gases remain the same • Infrared emission is proportional to temperature • Temperature increases emission increases • Equilibrium is maintained ATMOSPHERE (infrared) SURFACE Water Vapor Feedback When it gets warmer more water, a greenhouse gas, will be in the atmosphere Top of Atmosphere / Edge of Space • Higher temperature increases evaporation from land and ocean • Higher temperature allows air to hold more water • Increase of water increases thickness of blanket – increases temperature more •This is a positive feedback • Compensating circulation changes? • Think deserts … •Role of condensation and clouds?? ATMOSPHERE (infrared) SURFACE THIS INCREASES The Earth System: Feedbacks 3 Ice - Albedo When it gets warmer less ice Top of Atmosphere / Edge of Space • Less ice means less reflection warmer • Warmer means less ice • This could runaway! • Cooler works the other way ice-covered ICE The Earth System: Feedbacks 4 Clouds? Clouds are difficult to predict or to figure out the sign of their impact Top of Atmosphere / Edge of Space • Warmer more water more clouds • More clouds mean more reflection of solar cooler • More clouds mean more infrared to surface warmer • More or less clouds? • Does this stabilize? • Water in all three phases essential to stable climate CLOUD ATMOSPHERE (infrared) SURFACE Schematic Review go? CLOUD-RADIATIVE FEEDBACK ICE-ALBEDO FEEDBACK WATER VAPOR FEEDBACK TEMPERATURE FEEDBACK THE EARTH IS EXPECTED TO RESPOND TO THESE CHANGES FEEDBACKS POSITIVE: ACCELERATE WARMING NEGATIVE: DAMP WARMING Cloud-Ice-Atmosphere Feedback • Some carry away messages – This is where much of the discussion about scientific uncertainty resides. – The Earth is at a complex balance point • That balance relies on water to exist in all three phases. – Too warm could run away to “greenhouse” – Too cold run away to “snowball” ice vapor – How clouds change is not completely understood and much argued. – Is there something in all of this that changes the sign; namely, that CO2 warming will be compensated by more cooling? • The Iris Effect? Is there a reason? • Is there a reason for the Earth to maintain the same average surface temperature in the presence of increasing greenhouse gases? dT H (T Tideal ) dt IF YES, THEN: A MAJOR MISSING ENERGY PROCESS CONTROL BY A DIETY OTHER ... ???? EVIDENCE FOR THIS? Following Energy through the Atmosphere • We have been thinking about – Things that absorb – Things that reflect – Responses to energy Feedbacks • We have kept in our mind, mostly, greenhouse gases. – Need to introduce aerosols Aerosols • Aerosols are particulate matter in the atmosphere. – They impact the radiative budget. – They impact cloud formation and growth. Aerosols: Particles in the Atmosphere Aerosols: Particles in the atmosphere. • Water droplets – (CLOUDS) • “Pure” water • Sulfuric acid • Nitric acid • Smog •… • Ice • Dust AEROSOLS CAN: • Soot REFLECT RADIATION • Salt ABSORB RADIATION • Organic hazes CHANGE CLOUD DROPLETS Earth’s aerosols Dust and fires in Mediterranean Forest Fires in US The Earth System Aerosols (and clouds) Clouds are difficult to predict or to figure out the sign of their impact Top of Atmosphere / Edge of Space • Warmer more water more clouds • More clouds mean more reflection of solar cooler • More clouds mean more infrared to surface warmer • More or less clouds? • Does this stabilize? • Water in all three phases essential to stable climate CLOUD ATMOSPHERE (infrared) SURFACE The Earth System: Aerosols Top of Atmosphere / Edge of Space Aerosols directly impact radiative balance • Aerosols can mean more reflection of solar cooler • Aerosols can absorb more solar radiation in the atmosphere heat the atmosphere • In very polluted air they almost act like a “second” surface. They warm the atmosphere, cool the earth’s surface. AEROSOLS ATMOSPHERE ? (infrared) SURFACE Composition of aerosols matters. •This figure is simplified. •Infrared effects are not well quantified South Asia “Brown Cloud” • But don’t forget – Europe and the US in the 1950s and 1960s • Change from coal to oil economy Aerosol: South & East Asia http://earthobservatory.nasa.gov/Newsroom/NasaNews/2001/200108135050.html Reflection of Radiation due to Aerosol http://earthobservatory.nasa.gov/Newsroom/NasaNews/2001/200108135050.html Atmospheric Warming: South & East Asia WARMING IN ATMOSPHERE, DUE TO SOOT (BLACK CARBON) http://earthobservatory.nasa.gov/Newsroom/NasaNews/2001/200108135050.html Surface Cooling Under the Aerosol http://earthobservatory.nasa.gov/Newsroom/NasaNews/2001/200108135050.html The Earth System Aerosols (and clouds) Aerosols impact clouds and hence indirectly impact radiative budget through clouds Top of Atmosphere / Edge of Space • Change their height • Change their reflectivity • Change their ability to rain • Change the size of the droplets CLOUD ATMOSPHERE (infrared) SURFACE Aerosols and Clouds and Rain Some important things to remember about aerosols • They can directly impact radiative budget through both reflection and absorption. • They can indirectly impact radiative budget through their effects on clouds both reflection and absorption. • They have many different compositions, and the composition matters to what they do. • They have many different, often episodic sources. • They generally fall out or rainout of the atmosphere; they don’t stay there very long compared with greenhouse gases. • They often have large regional effects. • They are an indicator of dirty air, which brings its own set of problems. • They are often at the core of discussions of geo-engineering Let’s take a breath • We have now seen the basics of the climate change problem – reduced it to an energy balance that is altered by changes in greenhouse gases and aerosols. • Absorption and reflection. – seen that there is significant natural variability in the climate – identified the role of the major components of the physical climate system – exposed the role of water in the physical climate – exposed a set of feedbacks that might affect the balance of the climate system Still taking a breath • We have not – Really looked at what the atmosphere and ocean look like observationally. – Talked about how we measure climate change – Talked about how we predict climate change – Talked about how we make attributions of climate change to greenhouse gases – Really addressed the role of “abrupt” climate change What do we know with significant certainty? Greenhouse Effect (Observation and Theory) Observations of the past. / Large and small climate shifts. / Relation between CO2 and Temperature Anticipate consequential rise in global temperature / Rapid enough to disrupt society and commerce Rapid CO2 increase / Comparable to ice age – temperate difference Is this simply curious or important? NO Greenhouse Effect (Observation and Theory) Anticipate consequential rise in global temperature / Rapid enough to disrupt society and commerce Observations of the past. / Large and small climate shifts. / Relation between CO2 and Temperature Rapid CO2 increase / Comparable to ice age – temperate difference Should we be concerned ? YES Modeling Now Let’s Go To Models • We have used heuristic models to develop some conceptual understanding of the greenhouse effect. • We have posed that the conservation equation is the foundation of a physical model. • There are also statistical models, which are based on the observed behavior and extrapolating that behavior into the future. • Some modeling subsets – – – – Mechanistic models Component models Coupled models ..... What is a Model? • Model – A work or construction used in testing or perfecting a final product. – A schematic description of a system, theory, or phenomenon that accounts for its known or inferred properties and may be used for further studies of its characteristics. • Numerical Experimentation – Given what we know, can we predict what will happen, and verify that what we predicted would happen, happened? What do we do? • We develop models based on the conservation of energy and mass and momentum, the fundamental ideas of classical physics. (Budget equations) For exampled, we considered the conservation of energy and CO2 in the ice core data CHANGES IN SOLAR HEATING T Heating Cooling H T t CHANGES IN CO2, WHICH CHANGE THE RATE OF COOLING CO 2 PCO2 LCO2 t The Earth System SUN CLOUD-WORLD ATMOSPHERE ICE (cryosphere) OCEAN LAND Symbolic Energy Balance Equation Atmosphere: Eat+t = Eat + t((Pa – LaEa) + (Traoil + Ma )) Symbols E = “Energy” P = Production L = Loss rate Tr = Transfer M = Motion Superscripts a is for atmosphere o is for ocean i is for ice l is for land Variables t = time t = time increment Symbolic Energy Balance Equation (Earth System) Atmosphere: Eat+t = Eat + t((Pa – LaEa) + (Traoil + Ma )) Ocean: Eot+t = Eot + t((Po – LoEo) + (Troail + Mo )) Ice: Eit+t = Eit + t((Pi – LiEi) + (Trioal + Mi )) Land: Elt+t = Elt + t((Pl – LlEl) + (Trloia + Ml )) A point • With this model we are now existing inside of the climate system rather than sitting out in space looking at the global balance. – Inside – we are especially interested in what goes on at the surface of the Earth – Inside – we have to worry about the climate every day, we don’t have the benefit of the average – Inside – we have to deal with the complexity • Conservation is still true, but you have to think about being embedded in the system, not a distant observer of the system What do we do? • We develop models based on the conservation of energy and mass and momentum, the fundamental ideas of classical physics. (Budget equations) • We determine the characteristics of production and loss from theory and observations of, for instance, the eruption of a major volcano and the temperature response as measured by the global observing system. Consider just the Production and Loss Rate (We call this forcing.) Pa – LaEa We can divide this, conceptually, into two: That in absence of the influence of the “industry” of humans • Variability of the sun • What volcanoes put in the atmosphere • Greenhouse gases prior to industrial revolution • Aerosols from, for instance, sea salt and desert dust That which includes the influence of the “industry” of humans • Changes in greenhouse gases due to burning of fuel • Aerosols from “industrial” emissions • Changes in gases due to changes in what is growing • Change in absorption and reflection due to land use change • More? What do we do? • We develop models based on the conservation of energy and mass and momentum, the fundamental ideas of classical physics. (Budget equations) • We determine the characteristics of production and loss from theory and observations of, for instance, the eruption of a major volcano and the temperature response as measured by the global observing system. • We attempt to predict the temperature (“Energy”) response. • We evaluate (validate) how well we did, characterize the quality of the prediction relative to the observations, and determine, sometimes with liberal interpretation, whether or not we can establish cause and effect. Schematic of a model experiment. T T Start model prediction Model prediction without forcing Model prediction with forcing Model prediction with forcing and source of internal variability Observations or “truth” Class News • A ctools site for all – AOSS 480 001 W08 • This is the official repository for lectures • Email [email protected] • Class Web Site and Wiki – Climate Change: The Move to Action – Winter 2008 Term • Wunderground Climate Page – Posted Introduction of the New Rough Guide – My recent series on models Readings on Local Servers • Assigned – Stott: External Forcings of 20th Century Climate – Andronova: Anthropogenic Forcing of 20th Century Climate • Of Interest – – – – NASA Langley: Aerosol Fact Sheet Terra Mission: Aerosol Fact Sheet NASA SVS: Aerosols over South Asia (1) NASA SVS: Aerosols over South Asia (2)