1) The document discusses evidence of past climate change from various proxy records like tree rings, ice cores, fossils, and historical paintings. It also examines factors that can influence the climate like solar activity, volcanic eruptions, greenhouse gases, and human activities. 2) Climate models project further warming in the coming decades and centuries depending on greenhouse gas emission scenarios, but they have uncertainties regarding changes in extreme events and regional impacts. 3) The climate system is complex and influenced by both natural and human factors interacting across different timescales, making both past and future climate changes difficult to predict precisely.

1. Climate ChangeHype or Reality?http://www.dimplex-resource.co.uk/gifs/energy_the_issues/eti_climateChange.jpg

2. Global System

3. Conceptual Global Climate SystemConsider alterations of processes within the systemSpaceEarthAtmosphereConsider energy and mass transfers across system boundaries and processes or events that may alter their magnitude

4. How do we know that climate is changing?What is the best evidence??

5. Individual Events CAN NOT be used As evidence of a trend!!!www.nationwidepaging.co.uk/ boscastle_flooding.jpgwww.kreybaby.comhttp://jrscience.wcp.muohio.edu/photos/hurricane-luis-dmsp.gifwww.stormchasing.com

6. FossilsIce Corewww.gi.alaska.eduwww.accustudio.comimages.encarta.msn.comPaintingsweb.utk.eduwww.blogula-rasa.comTree RingsVineyards

7. Mountain Treelines

8. http://www.swisseduc.ch/glaciersPainting by Birman1826Mer de Glace: French Alps2004Athabasca Glacier: Canadian Rockies: www.sonic.nethttp://www.royalhigh.edin.sch.uk/

9. Famous GraphGlobal records indicate 12 warmest years in the record have occurred since 1990 (record length 1881-2005)2005, 1998, 2003, 2002, 2004, 2001, 1999, 1995, 1990, 1997, 1991, 2000Newer version in IPCC 2007 reporthttp://cdiac.esd.ornl.gov/trends/temp/lugina/lugina.html

11. IPCC (Intergovernmental Panel on Climate Change) Verdict“Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea-level”IPCC (2007) Summary for Policymakers, p5.Notice past changes identified are gradual, not catastrophic storms/hazards etc

12. Past Temporal Fluctuations

13. Temporal FluctuationsSource: Moran & Morgan (1994). Meteorology. Macmillan College Publishing Co., New York, NY

14. Temporal FluctuationsSource: Moran & Morgan (1994). Meteorology. Macmillan College Publishing Co., New York, NYWhether we consider ourselves to be in comparatively warm or cool period is dependent upon length of time scale under investigation. Last 10,000 years indicates current relative cooler phase, whereas last 1,000 years shows relative warmer phase. Climate System is always changing!

15. The Enhanced “Greenhouse Effect”Heat increased due to elimination of advection, i.e. no heat is transported away from the surfaceHeat increased by re-emission of energy by radiatively active gases

16. Historic Carbon Dioxide LevelsAccepted idea that CO2 levels trigger climate change, positive relationship with temperaturehttp://upload.wikimedia.org/wikipedia/en/c/c7/CO2-Mauna-Loa.png

17. Carbon Dioxide Levels vs Temperature?Majority View: Sponge Effect?Wavelength selective absorption

18. Many influences on climate but they work at different time scalesSource: Moran & Morgan (1994). Meteorology. Macmillan College Publishing Co., New York, NY

19. EXTERNAL FACTORSNatural external forcing agentsGlobal solar energySunspot cyclesIntergalactic dustImpacts on global solar distributionMilankovitch theory

20. Solar Influence: SUNSPOTSA) Cycle (approximately every 11 years)B) Longer term fluctuation linked to European temperatures, e.g. Maunder minimum and the Little Ice Age (1645-1715)Length of cycle linked to temperature?Minor influenceSource: http://science.nasa.gov/ssl/pad/solar/greenwch/spot_num.txthttp://www.astro.washington.edu/ivezic/Astr598/sunspot.gif

21. Climatic Aspects and Sunspot Cycle

22. Sunspot Cycle Length

23. Long-time scale

24. Milankovitch HypothesisObliquity of rotation to orbital planeCurrently 23.4º but varies between 22º and 24.5º over a 41,000 year cycleGreater influence felt towards the polesEccentricity of orbit around the sunVaries from almost circular to more elliptical than present over two cycles, 96,000 and 413,000 yearsCurrent annual variation of global solar energy approximately 5% but maximum variation of 30%Precession of equinoxesDefines the season when closest to the sun over a cycle of approximately 22,000 yearsBUT TOTAL RADIATION REMAINS CONSTANT

25. Milankovitch CyclesCorresponds well with cycles from proxy dataTheory, in terms of variation of global radiation, insufficient to account for changes in global temperaturesFeedback effects must also contribute to climate changeSource: http://www.doc.mmu.ac.uk/aric/gccsg/2-5-2-4.html

26. Milankovitch CyclesCombined effect is to redistribute energy inputTotal amount of radiation received by Earth in a year stays the same: so global effect?Snow and ice amplify effectsIn hemisphere with lower summer solar input and higher winter solar input – snow does not melt and ice sheets develop – initiates an ICE AGE.Dominance of N. Hemisphere

27. NATURAL INTERNAL FACTORSNatural Internal Forcing AgentsSolar Radiation forcingVolcanoesEarth evolutionOrogony (Mountain building)Continental DriftIncreasing time scale

28. VolcanicEruptions Only lasts a couple of yearshttp://cas.hamptonu.edu/centerinfo/photo-album/ScienceGraphics/images/volcano.jpg

29. Dust Veil Index (DVI)

30. Orogony and Continental DriftOrogonyMountain building due to tectonic forcesIncreases upland area which may hold snow longer, thus increasing solar reflection - coolingContinental DriftDictates ratio of land surface to ocean areas: supercontinentsDictates where land and sea are locatedLand and sea heat up differently and influence climateVERY LONG TIMESCALEPangaea

31. Continental DriftHigh Latitudes and Altitudes : Snow and Icemeans high albedo and cooling Low Latitudes: Vegetation or Desert (depends on precipitation) – former means cooling through the CO2 effect, later means warming.

32. HUMAN INTERNAL FACTORSAnthropogenic Internal Forcing AgentsHuman-based activity and land-use change such as urbanisationGrowth in existing natural background levels of greenhouse gases

33. Humans: Land Use ChangeDeforestationUrbanisationBUT: is this just local?http://www.bbc.co.uk/schools/gcsebitesize/geography/images/santiago.jpg

34. Major Greenhouse GasesSource: http://www.grida.no/climate/ipcc_tar

35. Major Greenhouse GasesClassified by activity type

36. Humans: Greenhouse GasesCurrent CO2 concentration: 380 ppmv – Parts per million volumeBetween 1970 and 2004, emissions have increased by 70%77% of total emissions is CO2But also note methane (CH4)and nitrous oxide (N2O)Forecast concentration, by 2100:500 – 1000 ppmv (wide range indicates economic uncertainty

37. GWP (Global Warming Potential)Note that methane is 63 times more powerful in the short term but has a relatively shorter atmospheric lifespan, hence only 9 times more powerful over 500 years

38. Composite ModelCombination of known factors appear to explain major changes in global climateSome doubt cast upon validity – see Idso, K.E. (2001) Predicting the past: Its not that difficult at http://www.co2science.org/edit/v4_edit/v4n4edit.htmSource: Gilliland, R.L. 1982. Solar, volcanic, and CO2 forcing of recent climate changes. Climatic Change4: 111-131.

39. The Future?Predictions based on modellingEnergy Balance ModelsGlobal Climate ModelsScenarios of CO2 consumption used: modelling of economics as well as atmosphereAIFI scenario leads to doubling of CO2 by 2050, and 1550 ppm by 2100.Alternative lesser increases used to indicate global action: B1 (600 ppm by 2100), AIT, B2, AIB, A2

40. Carbon Dioxide vs Temperature?NON-LINEARFatalistic ViewpointThresholds

41. Global Carbon CycleSMALLProblem:Figures don’t balanceBIGwww.globalchange.umich.edu

42. More cloudLess cloud?-veLess surface heatingLess convectionSurface heatingReduced albedo+veMeltingLess icePossible Feedback LoopsCloudsIce/Snow

43. UNKNOWNSPermafrost: Methane Releasehttp://www.geog.ucl.ac.uk/~jfogarty/GCM_essay.htmlhttp://www.planetextinction.com/images/Permafrost.jpg

44. Problems with GCM’sClouds not incorporated wellSerious deficiencies in treatmentChanges in snow/ice cover badly modelledAlbedo of snow highly significanCoupling of ocean and atmosphereThermal inertia of ocean systemsPolewards transport of energyMore confidence with temperature predictions than rainfall predictions: smooth vs spotty distributionFeedbacks can lead to instability in the model

45. Future PredictionsIntergovernmental Panel on Climate Change(IPCC)Predictions updated 1990, 1996 and 2001, 2007GlobalCurrent rates of warming around 0.1-0.2 deg C/decadeCurrent mean estimate of 1.8ºC<>4.0ºC by 2100 (depends on scenario)Constant 2000 concentrations: 0.6°C by 2100 (lag)Regional (see map)

46. Two main climate model typesOne way to avoid economic uncertainty is to predict for 2 *CO2, NOT a dateTransient (time series) – takes time to adjustEquilibrium: 1 * C02 vs 2 * CO2Model allowed to come into equilibriumTake the difference between the two predictions, i.e. + 2 deg C

47. Future Global change2 times CO2Most warming: Land, N hemisphere: Least certain: mid-latitudesGreen lines represent areas of uncertainty

48. Regional Detail: Europe: Hadley Centre GCMAnnual PrecipNote relativelypoor grid resolutionAnnual TempWinter PrecipSummer Precip

49. PREDICTING EFFECTS is not just temperature and precipitation?Most of the warming is focused in currently cold areas(snow and ice feedback) Logically this should reduce temporal and spatial variability of Earth’s climate at the surfaceThis may influence extreme events?

50. ThunderExtreme Events: StorminessWavesWindIce and SnowRain

51. Storm Tracks and GW

52. North Atlantic Cyclones: Western EuropeFITimeseries of the number of storm events recorded at 24 hour intervals. Timeseries of average intensity (mean pressure gradients)SymFSevereTimeseries of the number of severe lows (max gradient greater than or equal to 45m/250km)Timeseries of mean symmetry indexSource: Amanda Gibson (2006): Unpublished phD Thesis

53. Hurricanes: Uncertain Increase over N AtlanticFrom 1995 to present, butThere were similar high frequencies in the 1950s. Maybe a cycle: Maybe not?Statistics are inconclusive

54. Tornadoes:Uncertain DataChanges in reportingand better detectionmakes the data inhomogenous

55. MountainsComplicated landscape

56. Glacial Change in East Africa

57. Polar RegionsSensitive to change, snow is a natural cooling system, protects the groundas an insulator, frozen lakes can be used for transport, hunting etc.

58. Mediterranean: Desertification

59. Portsmouth: coastal flooding: Old Portsmouth 1989, but also both more and less rainfall?

60. So what can we do?Figure 1. Global average temperature change projected from 16 different climate models for the 21st century if atmospheric CO2 levels are held constant at the year 2000 levels.Figure 1. Global average temperature change projected from 16 different climate models for the 21st century if atmospheric CO2 levels are held constant at the year 2000 levels.http://www.worldclimatereport.com/index.php/2006/04/Sceptic website!

61. Future scenariosSource: IPCC 2007 Report: Mitigation of Climate Change

62. Conceptual Global Climate SystemShort-wave and long-wave energy balanceSunspot CyclesOrbital CyclesInterstellar Dust Radiative ForcingAtmospheric ChemistryVolcanic DustGas EmissionsSolar EnergyTerrestrial EnergySolar EnergySurface ConditionsThermodynamic ForcingGlobal Circulation Systems

63. SUMMARY POINTSClimate change at many time scales: past changes have been caused by many mechanisms superimposed upon one anotherChanges in mean temperature and or precipitation may be seen in the past reconstructions and modelled in the GCMs, but this is not the whole description of climateExtreme events are a real problem! to predict and understand! They are also not good to use as evidence of past or current climate change, and there is much uncertainty here.Many unknowns concerning degree and extent of response – we are interfering with a complex system Surely we should limit our interference as much as possible even though there are scientific and economic uncertainties?

64. Internet Resourceshttp://www.climnet.org/ A useful site belonging to Climate Action Network Europe, great linkshttp://www.ipcc.ch/ The Intergovernmental Panel on Climate Change: Read the 2007 Scientific Basis reporthttp://www.meto.gov.uk/research/hadleycentre/models/modeldata.html Met OfficeWeb site gives some model data and predictions for the futurehttp://www.realclimate.org/ Climate science from climate scientistshttp://www.co2science.org/scripts/CO2ScienceB2C/Index.jsp Alternative viewpointhttp://www.portsmouthcan.co.uk/ Local action network for climate change mitigation

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