1 MET 112 Global Climate Change MET 112 Global Climate Change - Lecture 12 Future Predictions Eugene Cordero San Jose State University Outline Scenarios Global Models Future Predictions 2 MET 112 Global Climate Change Climate Change and humans Anthropogenic increases in Emission scenarios have been developed Changes in solar irradiance and volcanic aerosols 3 MET 112 Global Climate Change Climate 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 model Q: How do we predict what the future climate will be like? A: Q: How do we predict what the future climate will be like? A: We use global models of the earth system Sequence of Steps 1. Estimate future GHGs concentration 2.Using future GHG levels, calculate what future climate (e.g. temp, precip) will be like. 3.Assess the uncertainty of the predictions 7 MET 112 Global Climate Change Calculation of Future CO 2 Concentrations Carbon Cycle Model Simulates atmosphere-biosphere and atmosphere-ocean interactions CO 2 8 MET 112 Global Climate Change Calculation of Future CO 2 Concentrations Carbon Cycle Model Simulates atmosphere-biosphere and atmosphere-ocean interactions CO 2 Emissions -How much is going into atmosphere CO 2 Concentration - How much remains in atmosphere 9 MET 112 Global Climate Change Carbon Cycle Models Atmosphere/ocean and atmosphere/biosphere interactions are complex. Model calculations contain uncertainty; the largest uncertainty: 10 MET 112 Global Climate Change Carbon 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 oceans 11 MET 112 Global Climate Change Past and Projected Future CO 2 Concentrations (Back-Up) 12 MET 112 Global Climate Change Past and Projected Future CO 2 Concentrations (Back-Up) (ppm) Parts per million Observations Model projections What factors affect future CO 2 levels? 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 countries What factors affect future CO 2 levels? Scenarios Emission Scenarios: Developed to account for range of possible future worlds SRES (special report on emission scenarios) Scenarios (1) 17 MET 112 Global Climate Change Scenarios (2) A1 storyline World of rapid economic growth Different branches dependent on energy type/use A1FI Fossil intensive continued dependence on coal/oil A1T A1B Balance between fossil and non-fossil A2 storyline Heteorogenous world technologies are not shared across borders, 18 MET 112 Global Climate Change 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 increase 19 MET 112 Global Climate Change Scenarios (3) B1 storyline Similar population as A1 Change in economic structures from product oriented to service oriented. B2 storyline Population like A2 More regionally oriented (not as much exchange between countries). 20 MET 112 Global Climate Change Scenarios (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). 21 MET 112 Global Climate Change CO 2 emissions for various scenarios Why a peak around 2050? 22 MET 112 Global Climate Change CO 2 emissions for various scenarios Note: global population peaks in 2050 and declines in some scenarios Why a peak around 2050? 25 MET 112 Global Climate Change Projected CO 2 Concentrations for Various Scenarios Note that even the low-emission scenarios result in greatly increased CO 2 concentrations by the year 2100 Max concentration (of scenarios shown): Min concentration (of scenarios shown): 26 MET 112 Global Climate Change Projected CO 2 Concentrations for Various Scenarios Note that even the low-emission scenarios result in greatly increased CO 2 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) 27 MET 112 Global Climate Change Climate Model A climate model is a mathematical representation of the physical processes that control climate Basically everything that affects climate Equations are very complicated Some of the worlds largest supercomputers are running climate models 28 MET 112 Global Climate Change 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 worlds largest supercomputers are running climate models 29 MET 112 Global Climate Change Model Schematic Climate Model Changes in greenhouse-gas concentrations and changes in albedo due to aerosols 30 MET 112 Global Climate Change Model Schematic Climate Model Changes in greenhouse-gas concentrations and changes in albedo due to aerosols Climate change (i.e. temperature, precipitation etc.) 31 MET 112 Global Climate Change Model Sensitivity Models (like the atmosphere) are sensitive systems. They can respond differently to the same radiative forcing, e.g., a doubling of CO 2 Thus, we use a range of models to determine the range of possible future scenarios. 32 MET 112 Global Climate Change Model Sensitivity Models (like the atmosphere) are sensitive systems. They can respond differently to the same radiative forcing, e.g., a doubling of CO 2 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. 33 MET 112 Global Climate Change 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. 34 MET 112 Global Climate Change 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. 35 MET 112 Global Climate Change Can we predict changes in past climate? Volcanoes, changes in solar radiation etc. Human emissions (CO2 etc.) Volcanoes, solar and humans What conclusions can you infer from these model experiments? 1. 2. 39 MET 112 Global Climate Change These experiments demonstrate that 1.The warming of the entire 20 th century is largely due to humans 2.The warming of the last 50 years is largely due to humans. 3.Natural factors are largely responsible for the warming of the 20 th century 4.Natural factors are not important in the early 20 th century, but more important in the last part of the 20 th century. 0 of 70 40 MET 112 Global Climate Change Climate models 1.Are not useful for predicting the temperature changes observed during the 20 th century. 2.Show that volcanic eruptions and changes in sunlight are responsible for most of the changes observed over the 20 th century. 3.Can predict the 20 th century observed temperature changes with natural factors only. 4.Can only predict the 20 th century observed temperature changes when they include both human and natural contributions. 0 of 70 What conclusions can you infer from these model experiments? 1.Models can reasonably predict temperature variations over the last 150 years. 2.Most of the observed warming in the past 50 years is attributable to human activities. 42 MET 112 Global Climate Change Future Predictions: Temperature 43 MET 112 Global Climate Change Notes on Temperature Projections Curves represent warming produced for seven scenarios by a model with average sensitivity. Each bar on the right represents a range of warming produced 44 MET 112 Global Climate Change Notes on Temperature Projections Projected Warming: 2000 2100 ranges from ~1.4C to ~5.8C. Curves represent warming produced for seven scenarios by a model with average sensitivity. Each bar on the right represents a range of warming produced by models of differing sensitivies for a specific scenario. Annual mean temperature change, 2071 to 2100 relative to 1990: Global Average in 2085 = 3.1 o C Land areas are projected to warm more than the oceans with the greatest warming at high latitudes Annual mean temperature change, 2071 to 2100 relative to 1990: Global Average in 2085 = 3.1 o C Annual mean precipitation change: 2071 to 2100 Relative to 1990 Some areas are projected to become wetter, others drier with an overall increase projected Annual mean precipitation change: 2071 to 2100 Relative to 1990 49 MET 112 Global Climate Change Sea Level 50 MET 112 Global Climate Change Sea Level Rise Annual mean precipitation change: 2071 to 2100 Relative to 1990 51 MET 112 Global Climate Change Recent Sea Level Changes 52 MET 112 Global Climate Change Main climate changes 53 MET 112 Global Climate Change Future predictions: main changes in climate Higher temperatures - especially on land Arctic shows the largest warming Hydrological cycle more intense More rain overall Sea levels rise Why? Changes at regional level hard to predict More intense weather (extremes) Floods, droughts etc. 54 MET 112 Global Climate Change Questions 1.Based on the A1FI scenario, what is the predicted CO 2 concentration, temperature change and sea level change in 2100? 2.Based on the A1T scenario, what is the predicted CO 2 concentration, temperature change and sea level change in 2100? 3.Explain the differences. 55 MET 112 Global Climate Change Based on the A1FI scenario, what is the predicted CO2 concentration in 2100? ppm ppm ppm ppm ppm 56 MET 112 Global Climate Change Based on the A1T scenario, what is the predicted temperature change in 2100? C C C C C 57 MET 112 Global Climate Change Based on the A1FI scenario, by the year 2100, sea level will increase by approx 1.1m 2.0.5m 3.0.3m 4.0.1m 5.0m 58 MET 112 Global Climate Change If CO 2 emissions stay constant, CO 2 concentrations will decline 1.True 2.False Mean Temperature (2050): relative to A1FI is A, B or C? B2 is A, B or C? A B C 60 MET 112 Global Climate Change Indicate the correct matching 1.A1FI A, B2 - B 2.A1FI B, B2 A 3.A1FI C, B2 A 4.A1FI A, B2 C 5.A1FI B, B2 - C 6.A1FI C, B2 B Mean Temperature (2050): relative to A1F A2 B2 62 MET 112 Global Climate Change A B C Constant Aerosols ____ Increasing aerosols____ Decreasing aerosols____ The correct order of the graph is (Constant, Increasing Aerosols and Decreasing Aerosols) 1.A B C 2.A C B 3.B A C 4.B C A 5.C A B 6.C B A 64 MET 112 Global Climate Change A B C Constant Aerosols Increasing aerosols Decreasing aerosols 65 MET 112 Global Climate Change Gateway to IPCC data IPCC Data Distribution Centre 66 MET 112 Global Climate Change Impact of climate change predictions What affect will these predictions have on the earth? Environment Business Society 67 MET 112 Global Climate Change 68 MET 112 Global Climate Change Therefore, stabilizing emissions is not enough to reduce the radiative forcing Based on above, how much will emissions have to decline in % to stabilize CO2 at 550ppm?