MET 112 Global Climate Change - Lecture 11Climate Change and humansSlide 3Slide 4Calculation of Future CO2 ConcentrationsCarbon Cycle ModelsPast and Projected Future CO2 Concentrations (Back-Up)Slide 8Slide 9Slide 10Slide 11Slide 12Scenarios (1)Scenarios (2)Scenarios (3)CO2 emissions for various scenariosProjected CO2 Concentrations for Various ScenariosClimate ModelClimate Modeling: Super ComputersNCAR’s “Blue Vista” IBM Power5Model SchematicModel SensitivityModel Verification: Can it be done?Slide 24Slide 25Slide 26These experiments demonstrate thatClimate modelsWhat conclusions can you infer from these model experiments?Slide 30Notes on Temperature ProjectionsLand areas are projected to warm more than the oceans with the greatest warming at high latitudesSome areas are projected to become wetter, others drier with an overall increase projectedSea LevelSea Level RiseRecent Sea Level ChangesFuture predictions: main changes in climateQuestionsSlide 39If CO2 emissions were stabilized at present day values, CO2 concentrations wouldMET 112 Global Climate Change - Lecture 11MET 112 Global Climate Change - Lecture 11Future PredictionsFuture PredictionsCraig ClementsCraig ClementsSan Jose State UniversitySan Jose State UniversityClimate Change and humansAnthropogenic increases in –greenhouse-gas concentrations–sulfate aerosols due to anthropogenic emissionsEmission scenarios have been developedChanges in solar irradiance and volcanic aerosols–Unpredictable and difficult to modelQ: How do we predict what the future climate will be like?A: We use global models of the earth system Global Climate Models (GCMs)Sequence of Steps1. Estimate future GHGs concentration2. Using future GHG levels, calculate what future climate (e.g. temp, precip) will be like. 3. Assess the uncertainty of the predictionsCalculation of Future CO2 Concentrations Carbon Cycle Model – Simulates atmosphere-biosphere and atmosphere-ocean interactionsCO2 Emissions -How much is going into atmosphereCO2 Concentration - How much remains in atmosphereCarbon Cycle ModelsAtmosphere/ocean and atmosphere/biosphere interactions not well understoodModel calculations contain uncertainty; the largest uncertainty: –Future uptake of carbon by the biosphere–Future uptake of carbon by the oceansPast and Projected Future CO2 Concentrations (Back-Up)(ppm) Parts per millionObservationsModel projectionsGlobal PopulationType of energy generation –Fossil intensive–Renewable energyGrowth of EconomyType of Economy–Material based–Service and information basedCooperation among countries–More homogeneous - share technologies–More isolated - larger divide between rich/poor countriesWhat factors affect future CO2 levels?The IPCC based its projections on six emission scenarios, running each one through sophisticated climate simulation programs.GovernanceDevelopmentLocalGlobalEnvironmentalEconomicA1 B1B2A2Adapted from Arnell et al. (2004). Global Environmental Change, 14:3-20A1BA1FIA1TGross Domestic Product Growth at 2100GovernanceDevelopmentLocalGlobalEnvironmentalEconomicA1 B1B2A2Adapted from Arnell et al. (2004). Global Environmental Change, 14:3-20Energy Use at 2100GovernanceDevelopmentLocalGlobalEnvironmentalEconomicA1 B1B2A2Adapted from Arnell et al. (2004). Global Environmental Change, 14:3-20GovernanceDevelopmentLocalGlobalEnvironmentalEconomicB1B2A2Adapted from Arnell et al. (2004). Global Environmental Change, 14:3-20A1BA1FIA1TTechnological Change at 2100Country ACountry BCountry CScenarios (1)Scenarios (2)A1 storyline–World of rapid economic growth–Population peaks 2050–Different branches dependent on energy type/useA1FI – Fossil intensive – continued dependence on coal/oilA1T – Non-fossil intensive energy use (Technology)A1B – Balance between fossil and non-fossilA2 storyline–Heteorogenous world –technologies are not shared across borders, –population continues to increaseScenarios (3)B1 storyline–Similar population as A1–Global exchange/cooperation–Change in economic structures from product oriented to service oriented.–Focus on social and economic sustainabilityB2 storyline–Population like A2–Similar environmental and social focus–More regionally oriented (not as much exchange between countries).CO2 emissions for various scenariosNote: global population peaks in 2050 and declines in some scenariosWhy a peak around 2050?Projected CO2 Concentrations for Various ScenariosNote that even the low-emission scenarios result in greatly increased CO2 concentrations by the year 2100–Max concentration (of scenarios shown): 970 ppm–Min concentration (of scenarios shown): 550 ppm– (Compare with current value: 370 ppm)Climate ModelA climate model is a mathematical representation of the physical processes that control climate–Basically everything that affects climate–Sun, atmosphere (greenhouse gases, aerosols), hydrosphere, land surface, cryosphereEquations are very complicated–Some of the world’s largest supercomputers are running climate modelsClimate Modeling: Super ComputersOne frame of an IBM Power5-575 series system. NCAR's “Blue Vista” will have 16 frames.Blue Vista will need over 250 kilowatts of power to operate. The average personal computer consumes 0.12 kilowatts . 78 IBM POWER5 nodes. Each node will have eight POWER5 simultaneous multithreading (SMT) processors 16 gigabytes of memory.NCAR’s “Blue Vista” IBM Power5Model SchematicClimate ModelChanges in greenhouse-gas concentrations and changes in albedo due to aerosolsClimate change (i.e. temperature, precipitation etc.)Model SensitivityModels (like the atmosphere) are sensitive systems. They can respond differently to the same radiative forcing, e.g., a doubling of CO2–This means that different models give different answers to the same problem–Thus, we use a range of models to determine the range of possible future scenarios.Model Verification: Can it be done?Before you can trust any of these models, they must be verified.–We can use past climate as a test.If your model can simulate the past climate, then there is a reasonable chance that the model can accurately predict future climate.Can we predict changes in past climate?Source: IPCC Climate Change 2007: The Physical Science Basis—Summary for Policymakers.Global Average Surface TemperatureSource: IPCC Climate Change 2007: The Physical Science Basis—Summary for