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Energy and the New Reality, Volume 1: Energy Efficiency and the Demand for Energy Services Chapter 1: Prospective Climatic Change, Impacts and Constraints L. D. Danny Harvey [email protected] Publisher: Earthscan, UK Homepage: www.earthscan.co.uk/?tabid=101807 This material is intended for use in lectures, presentations and as handouts to students, and is provided in Powerpoint format so as to allow customization for the individual needs of course instructors. Permission of the author and publisher is required for any other usage. Please see www.earthscan.co.uk for contact details. Two strong reasons for becoming more efficient in the use of energy: • Global Warming (discussed this hour) • Peak oil (dealt with in transportation PS) Heating trapping (“forcing”) due to variations in greenhouse gas (GHG) concentrations over the past 45 million years (Ma), as inferred from various lines of geological evidence, compared with the range of GHG forcing projected by 2100 under business as usual scenarios. The last time the forcing or heat trapping was a high as is projected for 2100, there was no ice anywhere on this planet. Controls over the Earth’s Climate • The Earth’s climate is governed by the balance between absorption of solar radiation and emission of infrared radiation • Any imposed alteration in either term is called a radiative forcing • Following a radiative forcing, the temperatures of the Earth’s surface and atmosphere will naturally adjust to bring solar absorption and infrared emission back into balance The “greenhouse” effect • Refers to the partial absorption by certain gases in the atmosphere of infrared radiation emitted by the Earth’s surface • Because absorption of any radiation (whether solar or infrared) has a warming effect, this makes the climate warmer than it would be otherwise (by about 33ºC for the naturallyoccurring greenhouse effect) • The key GHGs are: water vapour, CO2, ozone (O3), methane (CH4) and nitrous oxide (N2O) Human Impacts on Climate • Humans have directly emitted and increased the concentrations of CO2, CH4, N2O and various artificial GHGs (CFCs, HCFCs, HFCs, SF6), and pollutant emissions (NOx, CO and hydrocarbons) have lead to an increase in ground-level ozone • This in turn has caused a radiative forcing so far of about 2.5-3.5 W/m2 • If CO2 alone were to double, the radiative forcing would be about 3.75 W/m2 • Thus, the GHG increases so far are already equivalent to a 70-90% increase in CO2 400 5000 X Present 4500 350 300 4000 CO2 3500 250 3000 200 2500 2000 150 100 Present X CH4 1000 50 0 400000 1500 500 0 300000 200000 100000 Years Before Present 0 Methane Concentration (ppbv) Carbon Dioxide Concentration (ppmv) Figure 1.1 Variation in CO2 and CH4 Concentration The trapping of radiation initiates a series of feedbacks that ultimately determine how much warming we will eventually get. Some of the key feedbacks are: • Warming leading to more water vapour (which is a GHG) in the atmosphere, causing further warming • Warming lead to melting back of ice and snow (which otherwise reflect solar radiation), leading to more absorption of solar radiation at the surface and more warming The key parameter in the whole global warming issue is called the climate sensitivity. The is defined as the eventual (i.e., after the climate system has had enough time to adjust) global average warming for a fixed doubling of the atmospheric CO2 concentration Four independent lines of evidence are in broad agreement in indicating that the climate sensitivity is highly likely (say, 90% probability) to lie between 1.5ºC and 4.5ºC. That is, we expect each CO2 doubling (or its radiative equivalent) to eventually warm the climate by 1.5-4.5 C in the global mean. The four lines of evidence are: • Simulations of individual feedback processes with 3-D coupled atmosphere-ocean climate models • Comparison of observed global average warming over the past century (0.6-0.8ºC) and the gradual increase in estimated net radiative forcing (as GHGs have increased in concentration) over this time period • Comparison of estimated global mean temperature changes and radiative forcings at various times during the geological past • Comparison of inferred and simulated natural variations in the atmospheric CO2 concentration during the last few 100 million years with different assumed values for the climate sensitivity (which plays a critical role in initiating processes that eventually limit the magnitude of slow, natural fluctuations in CO2 concentration) Thus, by the time we get the radiative equivalent of 4 x pre-industrial CO2 concentration (the end of this century under business-as-usual scenarios), we can expect an eventual global mean warming of 3.0-9.0ºC (2 doublings at 1.5-4.5ºC each, assuming a linear response) Figure 1.4 Global mean temperature change for business-as-usual and aggressive (near zero emissions before 2100) emission-reduction scenarios in which the CO2 concentration is stabilized at 450 ppmv o Temperature Change ( C) 7 6 BAU, DT2x=4oC 5 Stabilization, DT2x=4oC 4 BAU, DT2x=2oC 3 2 Observed 1 0 -1 1850 Stabilization, DT2x=2oC 1900 1950 2000 Year 2050 2100 Supplemental Discussion: What has been observed so far? Figure 1.2 Variation in global average surface temperature, 1856-2009 0.6 o Temperature Change ( C) 0.4 0.2 0.0 -0.2 -0.4 -0.6 1856 1881 1906 1931 Year 1956 1981 2006 Figure 1.3 Reconstructed and directly observed (‘Instrumental’) variation in NH surface temperature 0.8 Esper 2002 Temperature Change (o C) 0.6 Huang 2004 Rutherford 2005 Moberg 2005 0.4 Mann et al 2008 Instrumental 0.2 0.0 -0.2 -0.4 -0.6 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 Year Figure 1.5 Business as usual change in global mean temperature in the context of observed or inferred past variations 5 Pessimistic Projection Optimistic Projection o Temperature Change ( C) 4 3 2 1 Various Inferred Variations Observed 0 -1 1000 1200 1400 1600 Year 1800 2000 2200 Sea ice extent, Sept 2005 (white) and average extent during the 1980s (pink line) Source: National Snow and Ice Data Center (NSIDC), USA, http://nsidc.org/news Sea ice extent, Sept 2007 Source: NSIDC, http://nsidc.org/news Sea ice extent, Sept 2009 Source: NSIDC, http://nsidc.org/news September 2010 September 2012 Exhibit 1-40: Minimum annual extent of Arctic sea ice (occurring in Sept of each year) Source of data: National Snow and Ice Data Center, Boulder, Colorado Summer Melting of Greenland Ice Cap Source: Konrad Steffen (cires.colorado.edu/steffen/greenland/melt2005) Source: Fettweis et al (2007), Geophysical. Research Letters 34, L05502 Sea level rise – 20 cm since 1880 Source: IPCC 2007, AR4, WG1 Major Impacts of Concern • Sea level rise of 6-12 m over several centuries to a 1000 years or more • Increased occurrence of drought, with major (20-30% and more) reductions in food production in many regions • Increased water stress in vulnerable regions • Species extinction (1/3 to ½ this century) • Acidification of the oceans Source: Nature 447, 145-147 (2004) Source: Nature 439, 143-144 (2006) Source: Nature 442, 978-980 (2006) Dissolution effects on coccoliths Source: Ruttimann (Nature 442, 978-980, 2006) What are the solutions? • More efficient use of energy • Moderation in our material demands • Massive deployment of renewable energy United Nations Framework Convention on Climate Change (1992) • Ratified (and therefore accepted) by almost every country in the world • Declares as its goal the “stabilization of greenhouse gas concentrations in the atmosphere at a level that prevent dangerous anthropogenic interference in the climate system” • To be “safe” in choosing allowed concentrations, we have to assume that the climate sensitivity is near the high end of the uncertainty range (i.e., around 4.5ºC) UNFCC (continued) • Any given real CO2 concentration corresponds to a higher effective concentration when we add in the heating effect of other GHGs • Thus, 450 ppm CO2 corresponds to at least 560 ppmv (a doubling of the pre-industrial concentration of 280 ppmv) • As a doubling could warm the climate by 4.5ºC, and if this is unacceptable, then we need to keep the real CO2 concentration to below 450 ppmv if we are to play it safe (as required by the UNFCCC). • We are currently (2012) at about 390 ppmv. Cancun Accord, Article 4 “The Conference of Parties … recognizes that deep cuts in global greenhouse gas emissions are required according to science … with a view to [holding] the increase in global average temperature below 2oC above preindustrial levels, and that the Parties should take urgent action to meet this goal … also recognizes the need to consider … strengthening the long-term goal to a global temperature rise of 1.5oC.” Source: United Nations, Framework Convention on Climate Change, The Cancun Agreements: Outcome of the work of the Ad Hoc Working Group on Long-term Cooperative Action under the Convention, FCCC/CP/2010/7/Add.1 (15 March 2011), online: <http://unfccc.int/resource/docs/2010/cop16/eng/07a01.pdf> Business-as-usual scenario: 3-6oC global mean warming by 2100 Source: IPCC AR5, WG1, SPM Fig. 7a Table 1 of WG2 SPM summarizes the risks of 2oC and 4oC global mean warming in such areas as: • • • • • • • Wildfires Drought Food production Forest health Human health are mortality Sea level rise Ocean acidification (caused by the CO2 increase associated with various amounts of warming) AR5 WG2 finds that • “Very High” risks are expected in almost all impact areas with 4ºC warming and current levels of adaptation. These risks can be reduced to “medium” in some sectors with high levels of adaptation • “Medium” to “Very High” risks are expected even for a 2ºC warming with current levels of adaptation. These risks can be reduced to “Medium” for all sectors with strong adaptation. Total allowed cumulative emissions vs allowed global mean warming Source: IPCC AR5, WG1, SPM Fig 10 Where is Canada heading? Canadian conventional and tar sands oil production, historical and industry hoped-for •7.0 •Source: CAPP (2013) •Source: CAPP (2013) All proposed pipelines and more are needed to meet tar sands expansion plans •Source: •CAPP (2013) 900 862 850 Greenhouse Gases (MT CO2eq) without measures Reductions from "without measures” scenario = 128 Mt 800 750 734 historical emissions 700 Additional reductions required = 122 Mt with current measures 650 612 600 Canada’s 2020 target 550 1990 1995 2000 2005 2010 2015 2020 Decomposition of past and future fossil fuel CO2 emissions according to the Kaya identity • Emission = Population x GDP/P x Energy Intensity x C Intensity, or • E = P x ($/P) x (MJ/$) x (kgC/MJ) Figure 1.6b Global population and global mean GDP/P and energy and carbon intensities 20 Carbon Intensity 9 18 8 7 16 Energy Intensity 14 6 12 5 10 4 8 3 GDP/P Population 6 2 4 1 2 0 1965 1975 1985 Year 1995 0 2005 Energy Intensity (MJ/$), Carbon Intensity (kgC/GJ) Population (billions), GDP/P (1000$/P) 10 Figure 1.6a Global population, GDP, primary energy demand and CO2 emission 500 Primary Energy, EJ/yr Emission, GtC/yr 8 400 Population, billions 6 300 4 200 World GDP, 10s trillions $ 2 0 1965 1975 1985 Year 1995 100 0 2005 Primary Energy (EJ/yr) Emission (GtC/yr), Population (billions), GWP (10s trillions $/yr) 10 Figure 1.8 Hypothetical variation in atmospheric CO2 concentration leading to stabilization at the indicated concentrations 700 CO2 Concentration (ppmv) 750 ppmv 650 ppmv 600 550 ppmv 500 450 ppmv 400 350 ppmv 300 2000 2025 2050 Year 2075 2100 Figure 1.9a: C emissions under BAU and as allowed for stabilization at various CO2 concentrations Figure 1.9b: Primary power from fossil fuels under BAU and permitted with stabilization at 450 ppmv CO2 Simplification of Figure 1.9b C-Free Primary Power (TW) Figure 1.9c Carbon-free primary power supply required for stabilization at various CO2 concentrations, given BAU growth in energy demand 40 35 30 25 2005 world total primary power demand 350 450 550 20 650 750 15 10 5 0 2000 BAU 2020 2040 2060 Year 2080 2100 The preceding projection of energy demand, and the required C-free power supply for stabilization of CO2 at 450 ppmv, assumes that energy intensity (MJ/$) decreases by only 1%/yr. If it decreased at a fast rate, the growth in total energy demand would be smaller, so – for a given allowed (and declining) fossil fuel supply, the require Cfree power supply would be smaller. Required Carbon-Free Power (TW) Figure 1.10: Trade-off between the rate of decrease in energy intensity and the amount of C-free power required in 2025, 2050, 2075, and 2100 for stabilization of atmospheric CO2 at 450 ppmv 40 Total Primary Power in 2005 2100 30 2075 C-free Primary Power in 2005 20 2050 10 2025 0 1.0 1.5 2.0 2.5 Rate of Energy Intensity Decline (%/yr) 3.0 Recall: Decomposition of past and future fossil fuel CO2 emissions according to the Kaya identity • Emission = Population x GDP/P x Energy Intensity x C Intensity, or • E = P x ($/P) x (MJ/$) x (kgC/MJ) Thus: • To stabilize atmospheric CO2 at no more than 450 ppmv (and possibly declining thereafter) requires (for the baseline population and GDP/P assumptions) either 21 TW of C-free power by 2050 (almost 1.5 times current total world primary power demand) and continuation of the recent rate of improvement of global mean energy intensity by 1%/yr, or • Accelerating the rate of improvement of energy intensity to an average of 3.0%/yr between 2005-2050 and increasing the current C-free primary power supply by about 50%, or • Some combination involving partial achievement of both the energy efficiency and C-free power supply requirements given above. Figure 1.11 Tranches of carbon-free power required with progressively smaller rates of decrease in energy intensity Extra for 1.0%/yr vs 1.5%/yr Extra for 1.5%/yr vs 2.0%/yr Extra for 2.0%/yr vs 2.5%/yr Extra for 2.5%/yr vs 3.0%/yr For 3.0%/yr 35 30 25 20 15 10 5 00 21 90 20 80 20 70 20 60 20 50 20 40 20 30 20 20 20 10 20 00 0 20 Primary Power (TW) 40 Figure 1.12 Factor by which energy intensity decreases for various annual rates of decrease 5.0 3.0%/yr 2.5%/yr Factor 4.0 2.0%/yr 1.5%/yr 3.0 1.0%/yr 2.0 1.0 0.0 2000 2010 2020 2030 Year 2040 2050 Summary on Global Warming • The world’s climate is warming (almost 1ºC in the global average since late 1800s), and on this there is near unanimous scientific agreement • This warming is largely due to human emissions of GHGs, and on this there is also almost as unanimous scientific agreement • Warming could reach 3-6ºC by the end of this century under business-as-usual assumptions, and more the following century, with dire consequences (strong scientific agreement), • There is, however, much that we can do to greatly reduce (but, unfortunately, not eliminate) further warming – but it will require fundamental changes in our energy systems and ways of thinking but (I will argue later) with little real impact on our standard of living