1 / 72

Environmental Science

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

dante
Télécharger la présentation

Environmental Science

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Environmental Science Unit 2 – Climate Change(STE Chapter 12, pp. 253-268)(STE Chapter 2, pp. 26-27)

  2. 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

  3. The Atmosphere Atmospheric Greenhouse Effect Greenhouse gases?

  4. Moelcular Models Build and draw models of the atmospheric gases Red = O Blue = N Black = C White = H

  5. Atmospheric Composition Permanent Variable

  6. Question Complete the following table: Nitrogen O2 Respiration Argon H2O Carbon Dioxide CH4 GH gas Ozone Protection from UV

  7. No. 1 Greenhouse Gas % = pph = ppm / 10,000 ppm / 10,000 0.0350 = 350/10,000 Mean surface T = 15 ºC

  8. 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.

  9. Experiment: GH in a Jar • Design an experiment to show the GH effect

  10. What is Radiation? • What is radiation - electromagnetic waves? • Characteristics of a wave… • Q: What are typical wavelengths of radiation??

  11. Comparitively Speaking… Visible = SW Infrared = LW Energy

  12. 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?

  13. 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/

  14. Animation http://news.bbc.co.uk/2/shared/spl/hi/sci_nat/04/climate_change/html/greenhouse.stm

  15. Animation

  16. 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.

  17. Why are CO2 and H2O GH Gases Whilst O2 and N2 are not? • They can vibrate – stretch and bend

  18. Movie

  19. End • Review

  20. Evidence for Global WarmingArrhenius First proposed by Arrhenius in 1896 Arrenhius predicted effect would be seen in 3000 years

  21. Evidence for Global WarmingKeeling Curve 1958: Keeling began measuring CO2 at Mauna Loa, HI

  22. Movie

  23. 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

  24. Evidence for Global WarmingGlobal Warming • What is it? • An enhanced atmospheric greenhouse effect due to man-made pollutants

  25. 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

  26. 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

  27. More Sources • Methane (CH4) • Agriculture • Rice paddies • Nitrous oxide (N2O) • Agriculture

  28. 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 CO2makes it the most important greenhouse gas.

  29. Movie 96 mins http://www.climatecrisis.net

  30. End • Review

  31. Further Evidence for Global WarmingTemp 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

  32. Data How do we take the Earth’s temperature? Direct records Proxy (indirect)records

  33. Temperature has fluctuatedIce Cores • Bubbles of trapped air between snowflakes • How is it dated? • How do we find temperature?

  34. Temperature has fluctuatedCooling 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

  35. Carbon Dioxide Levels Muana Loa Readings CO2 Levels Since 1958 370 350 CO2 (ppm) 330 310 40 30 20 10 0 420 370 320 CO2 (ppm) 270 220 Dome Concordia Vostok Ice Core 170 600000 400000 200000 0 Time (YBP)

  36. Temperature has fluctuatedCooling and Warming • Natural? • Volcanoes • Milankovich cycles • Solar activity • Man-made? Trace gases • Combination of both? • Increase in last 1000 yrs

  37. Temperature has fluctuatedVostok – 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

  38. “Hockey Stick” Controversey 0.6 Direct temperature measurements Mann et al. 1999 0.4 0.2 0 Temperature Change (°C) -0.2 -0.4 -0.6 -0.8 1000 1200 1400 1600 1800 2000 Year

  39. Last 1000 Years – N. HemisphereControversial ‘Hockey Stick’ Graph 1980+ Above baseline Zero-point is arbitrarily set at average temperature of the globe between 1960-1990 Error envelope Small natural variability Natural cooling trend, sudden warming exceeds error envelope Arctic Climate Impact Assessment IPCC

  40. 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

  41. 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

  42. 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

  43. End • Review

  44. Consequences of a Warmer World • What will happen?

  45. Sun CO2 removal by plants and soil organisms Greenhouse gases Cooling from increase Heat and CO2 removal CO2 emissions from land cleaning, fires, and decay Warming from decrease Aerosols Heat and CO2 emissions Long-term storage Troposphere Ice and snow cover Shallow ocean Land and soil biotoa 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

  46. Sea level rise, erosion Weather extremes, heat waves Loss of biodiversity, extinction Drought, flooding, water stress Loss of forests Agricultural yield decrease Consequences of a Warmer World

  47. Movie • CNN Global Warming Effects • CNN Rising Global temperatures • ABC Global Warming • ABC Alaska Adventure

  48. Consequences of a Warmer WorldFeedbacks • 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

  49. Consequences of a Warmer WorldSinks • 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

  50. 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).

More Related