Week 11 (the last week) Changing mood in the US

Transcription

1 Week 11 (the last week) Reminders: CLUE session this week: normal time and place Finally Current Event due Thursday at 5pm HW #7 due on Friday at 5pm Final Exam on Thursday Dec 17th 8:30-10:20am (here) More info on Wednesday Help session on Sunday evening (TBA) Today: Copenhagen 2009 Readings: Today: political solutions, pgs Tuesday the predicament, pgs Wednesday technology, pgs Today & Tuesday: Energy Today and Tomorrow Wed: Geoengineering Thur: Geoengineering/Summary of class Thur/Fri sections: review for exam Changing mood in the US Major companies combine with environmental groups to for US Climate Action Partnership ( Duke Energy, Dow Chemical, DuPont, Ford, GE, Pepsi, PG&E, Shell, etc. Environmental Defense Fund, Natural Resources Defense Council, Nature Conservatory, Pew Center on Global Climate Change, World Resource Institute calling on the federal government to quickly enact strong national legislation to require significant reductions of greenhouse gas emissions

2 On the road to Copenhagen US pledge 17% reduction in greenhouse gas emissions over that in 2005 (1.628 Gt) to Gt/yr by 2020 For reference, the Kyoto US target (not ratified) was Gt/yr by 2012 Pledge target for 2020 is consistent with the Bill that was passed by the US House in June and the Bill introduced in the Senate in September 83% reduction by 2050 China pledge: 40 to 45% reduction in carbon intensity by to 2.51 Gt/yr by 2020 (depending on GDP growth rate) NB: Carbon intensity is defined as Carbon emitted / GDP India pledge 20-25% reduction in carbon intensity by 2020 Approximately 0.78 Gt/yr by 2020 (depending on GDP growth rate) EU pledge 20% reduction below 1990 levels by 2020 (approx 0.94 Gt/yr) Pledge: a non-binding commitment Obama s pledge to Copenhagen of CO 2 Figure modified from fossil fuel carbon emissions if pledges are met: US, EU, India & China: 4.81 Gt/yr World: 8.5 Gt/yr

3 Possible outcomes of Copenhagen Global emissions will increase slightly through 2020 if US, EU, China and India honor their pledges Other developed countries agree to similar reductions in emissions Under constant global emissions, atmospheric CO 2 concentration will increase from 387ppm to ~415ppm Similar increases in other greenhouse gases (methane and nitrous oxide) Stumbling blocks to an agreement in Copenhagen Which countries will commit to hard limits on emissions and which countries will make pledges for emission reductions? Can developing countries develop using more expensive energy? To what extend are the developed nations obligated to: subsidize alternative energy development in the developing countries? provide technological assistance to developing countries?

4 The Past and Present Energy Usage Where World Fossil Fuel use in 2000AD 85% of today s energy is from fossil fuesl Allocation of 6.2 GtC/yr Electricity: 40% Fuels used directly: 60% Electricity Transportation Heating

5 Kaya Identity for analyzing CO2 emissions F=P*g*e*f Emissions = Population GDP energy emissions person GDP energy Average Income Energy Intensity of the economy Goals: g (economic growth) e (energy efficiency) f (decarbonize energy system) Carbon Intensity of the energy system Population is growing 2007: 6.5 billion people 2050: 9-10 billion people --- a 50% increase

6 Countries are Developing The World Economy is (was!) Growing Global GDP growth rate (% per year) and who contributes Why are global emissions going up? Energy, CO2 emission Income per capita Population Energy Intensity

7 Energy Intensity of the Economy F = P*g*e*f Houghton Fig 11.3 Reminder: more than CO2 contributes to warming Usually convert other gases to an equivalent mass of CO2 that would cause the same forcing Amount shown is emitted (equivalent) CO2 To get emitted equivalent C, multiply by 12/44

8 The Future Where are we heading (business as usual)? Emission scenarios and projected climate change (review) What would it take to stabilize the climate so that the future was only, say, 3ºC warmer than 2000? How much do we have to cut emissions globally? Is it doable? In the long run, how much can we emit and keep the climate stable (at 3ºC warmer than 2000)? What does this imply for US emissions? Alternatives to reduced emissions: geoengineering (coming) The Future Where are we heading (business as usual)? Emission scenarios and projected climate change (review) What would it take to stabilize the climate so that the future was only, say, 3ºC warmer than 2000? What do we have to do to global emissions? Is it doable? In the long run, how much can we emit and keep the climate stable (at 3ºC warmer than 2000)? What does this imply for US emissions? Alternatives to reduced emissions: geoengineering (tomorrow)

9 Global Energy Demand Is Increasing. Why? Population increase; Economic Growth Sources of Energy: Past and Projected Notes: Energy from coal produces much more CO 2 than oil Energy used today is ~430 Quads, or 12.5 TWatts Energy needed in ~2050 is 680 Quads (~70% increase)

10 Emissions How much Carbon Dioxide will be released into the atmosphere? B1 (utopia) A2 (business as usual) A1B A2 A1B B1 Estimates depend on population and economic projections, future choices for energy, governance/policy options in development (e.g., regional vs. global governance) Global Annual Average Surface Temperature Model Uncertainty Referenced to the Average Temperature Solid lines: average of all models used. Number of models used varies; shaded area is the standard deviation of the models IPCC AR4, Fig 10.4

11 The Fundamental Problem: Resisting Temptation!* Houghton Fig 11.2 stabilize just below double pre-industrial prevent warming >2C AVAILABLE used so far Total Emissions for each Scenario are for time of stabilization Stabilization date is about AD Paths to CO2 stabilization: emission reduction requirements by 2050 < At stabilization > <--- Required Action ---> To achieve stabilization of CO2 at ~ 500 ppm, global emissions will have to be level or even decrease over the next 40 years, while population increases by 50% and developing countries develop (and thus energy demand increases 70%) IPCC 2007 WG III Table SPM.5

12 Categories of Emission trajectories for stabilization scenrios Paths to CO 2 stabilization VI V IV II I

13 Stabilizing atmospheric CO 2 at ~500ppm Stabilizing CO 2 at 500ppm (550 CO 2 equivalent) means that the global averaged temperature will increase by ~3 C High latitudes will warm more than tropics, subtropics will be drier by about 20%, etc. Not exactly the change in temperature at 500ppm, but close enough. The Future Where are we heading (business as usual)? Emission scenarios and projected climate change (review) What would it take to stabilize the climate so that the future was only, say, 3ºC warmer than 2000? What do we have to do to global emissions? Is it doable? In the long run, how much can we emit and keep the climate stable (at 3ºC warmer than 2000)? What does this imply for US emissions? Alternatives to reduced emissions: geoengineering (tomorrow)

14 Climate Stabilization: The Pacala & Sokolow analysis How do we avoid exceeding 500ppm of CO2? There is needless confusion about the options: on the one hand... IPCC (2001, WGIII): "technologies that exist in operation or pilot stages today" are sufficient to follow a less-than-doubling trajectory "over the next hundred years or more". on the other hand... Hoffert et al. (Science, 2002) claim that the IPCC analysis involves "misperceptions of technological readiness". They call, instead, for "revolutionary changes" in energy technology. Pacala and Sokolow argument... Basic research is needed to develop the revolutionary technologies needed for the 2nd half of this century and beyond. Meanwhile, we can solve the carbon/climate problem in the first half of the century "simply by scaling up what we already know how to do." Pacala and Sokolow (2004), Science 305, Stabilizing atmospheric CO 2 at ~ 500ppm In 2004, Pacala and Socolow proposed a scheme to achieve this goal Phase 1: Requires immediate cap on global CO 2 emissions and that economic growth over the next 50 years be achieved by ramping up (scaling up) existing technologies without increasing CO 2 emissions Phase 2: After 2054, requires rapid and substantial reductions in global emissions. Final emissions of all GH gases must level off by ~2100 to ~ 1.5 Gt/yr, or ~20% of present global emissions At that time, the ocean uptake will balance the human input (and the ocean will continue to acidify).

15 Past Emissions 14 Billion of Tons of Carbon Emitted per Year 7 Historical emissions (380) (320) Values in parentheses are ppm (1 ppm = 2.1 GtC) The Emission Stabilization Triangle Billion of Tons of Carbon Emitted per Year Historical emissions (380) Stabilization Triangle Currently projected path = ramp Flat path O (530) Copenhagen Pledge (470) Interim Goal (320) Interim 2054 goal: stabilize emissions immediately (yet increase energy by ~70% in 2054) and invest in technology to have much more energy with reduced emissions after that Pacala and Socolow (2004)

16 The Stabilization Triangle: settle for double or triple pre-industrial CO 2? 21 GtC/yr 14 7 Historical emissions (380) Ramp = Delay Flat = Act Now (470) Business As Usual (530) (750) Stabilization triangle! 500 ppm (830)! 850 ppm (320) 1.5 (500) (850) (500) (850) (500) Values in parentheses are ppm (1 ppm = 2.1 GtC). Stabilizing at 500ppm requires the global emission be 1.5 Gt/yr Pacala and Socolow (2004) Wedges 14 7 Billion of Tons of Carbon Emitted per Year Historical emissions Currently projected path Flat path O 14 GtC/y Seven wedges 7 GtC/y How do we meet the increase in energy demand (projected to increase by 70% by 2050 and 200+% by 2100) without increasing emissions of CO 2? Pacala and Socolow (2004)

17 What is a Wedge? A wedge is a strategy to reduce carbon emissions that grows in 50 years from zero to 1.0 GtC/yr. The strategy has already been commercialized at scale somewhere. Total = 25 Gigatons carbon 1 GtC/yr 50 years Cumulatively, a wedge redirects the flow of 25 GtC in its first 50 years. This would cost $1.25 trillion at $50/tC. A $50/tC tax or carbon trading value would raise electricity prices by almost 1 cent per kwh ( ~ 10%). Pacala and Socolow (2004) The Interim Goal is Within Reach Reasons for optimism that global emissions in 2055 need not exceed today s emissions: The world today has a terribly inefficient energy system. Carbon emissions have just begun to be priced. Most of the 2055 physical plant is not yet built Pacala and Socolow (2004)

18 Fill the Stabilization Triangle with Seven Wedges (~double the energy available in 2054 w/o increasing emissions) Energy Efficiency Methane Management 14 GtC/y Decarbonized Electricity Forests & Soils Stabilization Triangle GtC/y Decarbonized Fuels Fuel Displacement by Low-Carbon Electricity Nuclear Electricity Effort needed by 2055 for 1 wedge: 700 GW (twice current capacity) displacing coal power. Phase out of nuclear power creates the need for another half wedge. Graphic courtesy of NRC R. Socolow (per. comm.)

19 Wind Electricity Effort needed by 2055 for 1 wedge: One million 2-MW windmills displacing coal power. Today: 50,000 MW (1/40) Prototype of 80 m tall Nordex 2,5 MW wind turbine located in Grevenbroich, Germany (Danish Wind Industry Association) R. Socolow (per. comm.)