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Environmental Science Unit 2 – Climate Change (STE Chapter 12, pp. 253-268) (STE Chapter 2, pp. 26-27) Where are we going? - Composition of the Atmosphere - The Greenhouse Effect - Keeling Curve - Sources - Consequences of a Warmer World - Sea Level Rise - Temperature Records - Where are we now? - Solutions Atmospheric Greenhouse Effect Greenhouse gases? The Atmosphere Moelcular Models Build and draw models of the atmospheric gases Red = O Blue = N Black = C White = H Atmospheric Composition Permanent Variable Question Complete the following table: Gas % (by vol) Importance N2 78 N-cycle Oxygen O2 21 Respiration Argon Ar 1 Inert Water vapor 0-4 GH + Heat transport Carbon Dioxide H2O CO2 0.04 GH + photosynthesis Methane CH4 0.00017 GH gas Nitrous oxide N2O 0.00003 GH gas Ozone O3 0.000004 Protection from UV Particles/aerosols NA 0.000001 Energy budget Nitrogen Symbol No. 1 Greenhouse Gas % = pph = ppm / 10,000 ppm / 10,000 0.0350 = 350/10,000 Mean surface T = 15 ºC Question If water vapor is the #1 greenhouse gas why don’t we worry about it? Because it is thought that we can do little to alter its concentration in the atmosphere. Experiment: GH in a Jar • Design an experiment to show the GH effect What is Radiation? • What is radiation - electromagnetic waves? • Characteristics of a wave… • Q: What are typical wavelengths of radiation?? Comparitively Speaking… Visible = SW Infrared = LW Energy Consider IR, UV and VIS radiation: 1. Arrange them in order of inc. wavelength 2. Arrange them in order of increasing energy 3. How are these arrangements related to the Sun’s ability to heat a closed car? What is the Greenhouse Effect? SW in LW out Absorption by gases Re-emission of LW by gases http://earthguide.ucsd.edu/earthguide/diagrams/greenhouse/ Animation http://news.bbc.co.uk/2/shared/spl/hi/sci_nat/04/climate_change/html/greenhouse.stm Animation The Analogy • How is the atmospheric greenhouse effect different to a regular greenhouse? • Heat is not ‘trapped’, and the atmosphere does not act like a ‘blanket’…why? There is circulation of air in the atmosphere, no circulation in a regular glass greenhouse. Blankets prevent convection. Why are CO2 and H2O GH Gases Whilst O2 and N2 are not? • They can vibrate – stretch and bend Movie End • Review Evidence for Global Warming Arrhenius First proposed by Arrhenius in 1896 Arrenhius predicted effect would be seen in 3000 years Evidence for Global Warming Keeling Curve 1958: Keeling began measuring CO2 at Mauna Loa, HI Movie Evidence for Global Warming Keeling Curve • What is the significance of the Keeling curve? What could be responsible for this seasonal up-down fluctuation? Since 1958 atmospheric carbon dioxide has risen by more than 15% http://www.cmdl.noaa.gov/ccgg/index.html Evidence for Global Warming Global Warming • What is it? • An enhanced atmospheric greenhouse effect due to man-made pollutants Concentration of Energy Consumption Angola major oil producing country (3 cities) China and India are electrifying like crazy, much larger impact than US in next 50 yrs Sources of GH Gases • Carbon dioxide (CO2) – > 380 ppm – Rising – From fossil fuels – Deforestation Surprised not only by increase but by rate of increase Keeling curve again More Sources • Methane (CH4) – Agriculture – Rice paddies • Nitrous oxide (N2O) – Agriculture Global Warming Potential • Global warming potential (GWP) is measured relative to CO2 - Methane x 21 - Nitrous oxide x 270 - CFC’s x 140-12000 • Much LARGER INPUT of CO2 makes it the most important greenhouse gas. Movie 96 mins http://www.climatecrisis.net End • Review Further Evidence for Global Warming Temp change • Many groups have been working on compositing and quality control the instrumental data set for the globe • Thousands of sites – Record is short – Biased towards W Europe and E US Data Direct records How do we take the Earth’s temperature? Proxy (indirect) records Temperature has fluctuated Ice Cores • Bubbles of trapped air between snowflakes – How is it dated? – How do we find temperature? Temperature has fluctuated Cooling and Warming • • Normal oxygen 16O: contains 8 p+, 8 n 18O: contain 8 p+, 10n – this is an isotope of oxygen and is heavier than 16O • Isotope fractionation: – 16O evaporates more readily than 18O since it is lighter • Warm period, the relative amount of 18O will increase Carbon Dioxide Levels 420 Muana Loa Readings CO2 Levels Since 1958 CO2 (ppm) CO2 (ppm) 370 320 370 350 330 310 40 30 20 10 0 270 220 170 Dome Concordia 600000 Vostok Ice Core 400000 Time (YBP) 200000 0 Temperature has fluctuated Cooling and Warming • Natural? – Volcanoes – Milankovich cycles – Solar activity • Man-made? Trace gases • Combination of both? – Increase in last 1000 yrs Temperature has fluctuated Vostok – ancient atmospheres • • • • Furthest point from coastline, coldest place on earth -126 ºF Vostok pretty grim existence, largest graveyard by far End of last ice age about 10,000 yr BP 4 cycles most of the time either in an ice age or getting to one, warm conditions are rare (5% of time) abrupt changes Sensitvity - 80 ppm in CO2 produces a 10 ºC change at Vostok Lead lag issue, CO2 first then T, or otherway around “Hockey Stick” Controversey Temperature Change (°C) 0.6 0.4 Direct temperature measurements Mann et al. 1999 0.2 0 -0.2 -0.4 -0.6 -0.8 1000 1200 1400 1600 Year 1800 2000 Last 1000 Years – N. Hemisphere 1980+ Above baseline Controversial ‘Hockey Stick’ Graph Zero-point is arbitrarily set at average temperature of the globe between 19601990 Error envelope Small natural variability Natural cooling trend, sudden warming exceeds error envelope Arctic Climate Impact Assessment IPCC Climate Changes During Past 400,000 Years Past climate based on study of Antarctic glaciers Cycles of Ice Ages lasting about 100,000 years Interglacial Periods lasting 10,000 to 12,500 yrs Temperature has fluctuated • Now in warm interglacial period • Correlation between CO2 & mean temperature Not totally 1:1 correlation – tells us something about the complexity of the system Evidence of Warming • • • The 20th century was the hottest century in the past 1000 years. Mean global temperature rose about 0.6º C (1º F) in past 100 years During the last century, the world’s sea level rose by 10-20 cm, mostly due to runoff from melting and land-based ice and the expansion of ocean water as temperatures rise Arctic • Over the past 50 years, Arctic temperatures have risen almost twice as fast as those in the rest of the world – Glaciers and floating sea ice are melting and shrinking at increasing rates – Arctic as is most dramatic example of large changes Illustrates what all climate models show – ‘Polar amplification’ – Earth warms or cools more dramatically at both poles – Canary in coal mine Greenland – surface summer melting 80% • >3 C ice will melt, glacial melt End • Review Consequences of a Warmer World • What will happen? Sun Troposphere Greenhouse gases Aerosols Warming from decrease Cooling from increase CO2 removal by plants and soil organisms CO2 emissions from land cleaning, fires, and decay Heat and CO2 removal Heat and CO2 emissions Ice and snow cover Shallow ocean Land and soil biotoa Long-term storage Natural and human emissions Simplified model of major processes that interact to determine the average temperature and greenhouse gas content of the troposphere Deep ocean Stepped Art Consequences of a Warmer World • • • • • • Sea level rise, erosion Weather extremes, heat waves Loss of biodiversity, extinction Drought, flooding, water stress Loss of forests Agricultural yield decrease Movie • • • • CNN Global Warming Effects CNN Rising Global temperatures ABC Global Warming ABC Alaska Adventure Consequences of a Warmer World Feedbacks • Some factors can amplify (positive feedback) and some can dampen (negative feedback) projected global warming • There is uncertainty about how much CO2 and heat the oceans can remove from the troposphere and how long the heat and CO2 might remain there • Warmer temperatures create more clouds that could warm or cool the troposphere Consequences of a Warmer World Sinks • Increased CO2 in the troposphere can increase plant photosynthesis (PS) but: – The increase in PS would slow as the plants reach maturity. – Carbon stored by the plants would be returned to the atmosphere as CO2 when the plants die. – Increased PS decreases the amount of carbon stored in the soil. – Tree growth may temporarily slow CO2 emissions in the S. Hemisphere but is likely to increase CO2 emissions in the N. Hemisphere. – Movie – Forests and GW Consequences of a Warmer World Sea Level Rise ABC – Melting Ice Between 1979 and 2005, average Arctic sea ice dropped 20% (as shown in blue hues above). Consequences of a Warmer World Sea Level Rise Consequences of a Warmer World Sea Level Rise • Worst possible scenario: mass flooding in low lying areas e.g. islands (cf. Maldives) • CNN Movie • Due to thermal expansion of water more than glacier melt • All coastline cities, and river deltas e.g. Bangladesh, Pakistan, China, Egypt, Florida, Louisiana and other parts of the U.S 5m, 17 ft Ice Cube Demo • • • • Put some ice cubes in a glass Record the volume Wait for the ice to melt Record the new volume • Is there a difference? What has this got to do with GW? Consequences of a Warmer World Changing Ocean Currents • Storage of CO2 in deep water (x50) • Warming could decrease ability of ocean to serve as “sink” for carbon – Loss of phytoplankton • Positive feedback effect • Increased warming • Effects on the weather? Thermohaline conveyer Consequences of a Warmer World Effects on Biodiversity • Ecological Implications: • Shift of habitat to higher latitudes • Shift of habitat to higher elevations • Potential large loss of biodiversity Consequences of a Warmer World Agricultural Yield • In a warmer world, agricultural productivity may increase in some areas and decrease in others. • Crop and fish production in some areas could be reduced by rising sea levels that would flood river deltas. • Global warming will increase deaths from: – Heat and disruption of food supply. – Spread of tropical diseases to temperate regions. – Increase the number of environmental refugees. Future Scenarios Global Climate Models Projected warming of 1 to 3.5 º C between 1990 & 2100 Likely scenario: x2 CO2 (from 280 ppm to 560 ppm) before 2100 leading to warming of 2º C IPCC End • Review Solutions to Global Warming Solutions to Global Warming • Climate change is such a difficult problem to deal with because: – The problem is global – The effects will last a long time – The problem is a long-term political issue – The harmful and beneficial impacts of climate change are not spread evenly – Many actions that might reduce the threat are controversial because they can impact economies and lifestyles Solutions to Global Warming Two ways to deal with global warming Solutions to Global Warming Solutions • Sequester – Land – Ocean Solutions • Governments can tax greenhouse gas emissions and energy use, increase subsidies and tax breaks for saving energy, and decrease subsidies and tax breaks for fossil fuels • A crash program to slow and adapt to global warming now is very likely to cost less than waiting and having to deal with its harmful effects later Solutions: International Climate Negotiations: The Kyoto Protocol • Treaty on global warming which first phase went into effect January, 2005 with 189 countries participating • It requires 38 participating developed countries to cut their emissions of CO2, CH4, and N2O to 5.2% below their 1990 levels by 2012 • Developing countries were excluded. – The U.S. did not sign, but California and Maine are participating. – U.S. did not sign because developing countries such as China, India and Brazil were excluded Beyond the Kyoto Protocol • Countries could work together to develop a new international approach to slowing global warming. – The Kyoto Protocol will have little effect on future global warming without support and action by the U.S., China, and India Individual Action • In 2005, the EU proposed a plan to reduce CO2 levels by 1/3rd by 2020 • California has adopted a goal of reducing its greenhouse gas emission to 1990 levels by 2020, and 80% below by 2050 • Global companies (BP, IBM, Toyota) have established targets to reduce their greenhouse emissions 10-65% to 1990 levels by 2010 • Carbon Offsets (movie) Develop crops that need less water Waste less water Connect wildlife reserves with corridors Move hazardous material storage tanks away from coast Move people away from low-lying coastal areas Stockpile 1- to 5-year supply of key foods Expand existing wildlife reserves toward poles Prohibit new construction on low-lying coastal areas or build houses on stilts Education http://www.panda.org/campaign/powerswitch/take_action/ switchemoff.cfm Education • Latest news • Is not so good News paper stories • Russia ratifies Kyoto Protocol • Michael Howard said ‘the UK must lead on Climate Change’, Blair’s dire warning on climate change ‘what is now plain is that the emission of greenhouse gases is causing global warming at a rate that is simply unsustainabe in the long-term, and by long-term I do not mean centuries ahead, I mean within the lifetime of my children certainly and possibly my own…and by unsustainable I do not mean a phenonemon causing problems of adjustment, I mean a challenge so far reaching that its impact is so far reaching in its destructive power that it changes radically human existence • 7/03: US Senator Inhoffe senate hearing – with all this hysteria, all of the fear, all of the funny science could it be that manmade GW may be the greatest hoax ever perpetrated on the American people, it sure sounds like it.