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  • jkjlljk
  • From Jerry Meehl This slide shows the time evolution of globally averaged surface air temperature from multiple ensemble simulations of 20th century climate from the NCAR Parallel Climate Model (PCM) compared to observations. The simulations start in the late 19th century, and continue to the year 2000. The temperature scale at left is in degrees Centigrade, and temperature anomalies are calculated relative to a reference period averaged from 1890 to 1919. The black line shows the observed data, or the actual, recorded globally averaged surface air temperatures from the past century. The blue and red lines are the average of four simulations each from the computer model. The pink and light blue shaded areas depict the range of the four simulations for each experiment, giving an idea of the uncertainty of a given realization of 20th century climate from the climate model. The blue line shows the average from the four member ensemble of the simulated time evolution of globally average surface air temperature when only "natural" influences (solar variability and volcanic eruptions) are included in the model. Therefore, the blue line represents what the model says global average temperatures would have been if there had been no human influences. The red line shows the average of the four member ensemble experiment when natural forcings AND anthropogenic influences (greenhouse gases including carbon dioxide, sulfate aerosols from air pollution, and ozone changes) are included in the model. Note that this model can reproduce the actual, observed data very well only if the combined effects of natural and anthropogenic factors are included. The conclusion that can be drawn is that naturally occuring influences on climate contributed to most of the warming that occurred before WWII, but that the large observed temperature increases since the 1970s can only be simulated in the model if anthropogenic factors are included. This confirms the conclusion of the IPCC Third Assessment Report that most of the warming we have observed in the latter part of the 20th century has been due to human influences.
  • Graph shows Hadley Centre model prediction for areas with future cyclone generation (red/orange) in global warming scenario, compared to actual track of Catarina. Point out that observed trend in hurricane activity is still under debate. Globale Erwärmung  A) mehr Verdunstung  Trockenheit, B)mehr Wasserdampf  1) mehr Wasser kann fallen, 2) mehr latente Wärme Abschwächung des meridionalen Temp-gefälles  weniger Westwindwetterlagen Verschiebung von typischen Wetterlagen  mehr Extreme an einem Ort
  • In fact, ocean currents are extremely important in determining the climate of the world’s continents.  This model shows the major ocean currents, with orange representing warm surface currents and blue representing cold deep currents.  The light circles represent areas where heat is release into the atmosphere. 

Transcript

  • 1. CLIMATE CHANGE PAST, PRESENT AND FUTURE J.SRINIVASAN DIVECHA CENTRE FOR CLIMATE CHANGE INDIAN INSTITUTE OF SCIENCE BANGALORE
  • 2. This Book claims that Global warming is a hoax
  • 3.
    • Michael Crichton’s book refers specifically
    • absence of real world data
    • lack of model testing and validation
    • lack of independent assessments of models
  • 4. Planetary Emergency?
  • 5.
    • When scientists cannot predict tomorrow’s weather accurately , how can they predict the climate of the earth 50 years from now or what happened in the past ?
  • 6.
    • With so much at stake, it is right that climate science is subjected to the most intense scrutiny.
    • Michael Le Page , New Scientist .
  • 7. Climate is different from weather
    • Weather
    • Time scale
      • Hours-Days
    • Spatial scale
      • Regional
    • Main Components
      • Atmosphere
    • Climate
    • Time scale
    • Months-Years-Beyond
    • Spatial scale
      • Regional-Global
    • Main Components
      • Atmosphere, Ocean, Land… Humans
    CLIMATE IS WEATHER AVERAGED OVER TIME
  • 8. What controls climate?
    • Land surface
      • Albedo
      • Evaporation
      • Temperature
    • Oceans
      • Albedo
      • Evaporation
      • Energy transfer by ocean currents & vertical mixing
    • Greenhouse gases ( water vapor,
    • CO 2 , O 3 )
    • Solar radiation
      • Orbital controls
      • Latitude
    • Clouds
      • Albedo
      • Atmospheric emissivity
      • Absorption and scattering of solar radiation
    • Aerosols
      • Absorption and scattering of solar radiation
      • Condensation nuclei
  • 9. Climate Change
    • Natural -- Climate is in a continual state of flux due to natural causes
    • Anthropogenic -- Humans as climate change agents
  • 10. HOW DID THE CLIMATE OF THE EARTH VARY IN THE PAST ? WHAT FACTORS CONTROLLED THESE CLIMATE VARIATIONS?
  • 11.  
  • 12. Oscillation between ice-free and ice-covered earth
  • 13. MULTIPLE EQUILIBIRUM RADIATION
  • 14.  
  • 15.  
  • 16. From Oerlemans and Van Den Dool, 1978
  • 17. 5 Billion years Earth’s history
    • Mechanisms : Evolution of the Sun, Evolution of the Atmosphere
  • 18.  
  • 19. Important Greenhouse Gases
  • 20. Water exists in solid, liquid and gas from only on earth
  • 21. Greenhouse Effect
  • 22. Climate in the Last 180 million years
    • Mechanisms : Evolution of the Atmosphere, Plate Tectonics, Mountain Building, Volcanic Activity, Solar Variability, Ocean Circulation
  • 23. Mid-Cretaceous Climate (100 Ma)
    • Climate was warm during the Age of the Dinosaurs (the Mesozoic)
      • Alligators lived in Siberia!
      • Dinosaurs lived north of the Arctic Circle in Alaska!
    http://alaskageology.org/polardinos.html
  • 24.  
  • 25.  
  • 26. Long-term carbon cycle
    • Carbon added to atmosphere through metamorphic outgassing and outgassing of volcanoes and mid-ocean ridges
    • Hydrolysis-weathering of silicate minerals in continental crust:
      • CaSiO3 + H2CO3 >> CaCO3 + SiO2 + H2O
    • The products of continental weathering are transported to the oceans by rivers, where they are used to make CaCO3 and SiO2 shells of marine organisms. When these organisms die, many of them are deposited and buried on the seafloor. The carbon cycle is completed upon subduction and melting of these sediments. The melt may rise as magma, providing volcanoes and MORs with a source of recycled CO2.
    Important flows of carbon on 100,000 year time scales
  • 27. Last 1 million years
    • Mechanism: Orbital Parameters
  • 28. Last 120,000 years
    • Mechanism: Orbital Parameters
  • 29. Last 18,000 years
  • 30. GISP2 Drilling Project
  • 31.  
  • 32. Extracting An Ice Core
  • 33. Annual Layers In Ice Core
  • 34.  
  • 35.  
  • 36. Oxygen Isotopes
    • A small fraction of water molecules contain the heavy isotope 18 O instead of 16 O.
    • 18 O/ 16 O ≈ 1/ 500
    • This ratio is not constant, but varies over a range of several percent.
    • Vapor pressure of H 2 18 O is lower than that of H 2 16 O, thus the latter is more easily evaporated .
  • 37.  18 O
    • As water vapor is transported poleward in the hydrologic cycle, each cycle of evaporation and condensation lowers the ratio of H 2 18 O to H 2 16 O, in a process called fractionation.
    • This ratio is expressed as  18 O.
  • 38.  18 O and Global Ice Volume
    • As ice sheets grow, the water removed from the ocean has lower  18 O than the water that remains.
    • Thus the  18 O value of sea water in the global ocean is linearly correlated with ice volume (larger  18 O -> larger ice sheets).
    • A time series of global ocean  18 O is equivalent to a time series of ice volume.
  • 39.  18 O vs. Temperature
  • 40.  
  • 41. Figure 2.22: Variations of temperature, methane, and atmospheric carbon dioxide concentrations derived from air trapped within ice cores from Antarctica (adapted from Sowers and Bender, 1995; Blunier et al., 1997; Fischer et al., 1999; Petit et al., 1999).
  • 42. The cooling and warming during the ice ages and interglacial periods, however, was far greater than would be expected from the tiny changes in solar energy reaching the Earth Milankovitch Hypothesis
  • 43.  
  • 44.
    • The change in Solar radiation was amplified many times by positive feedbacks
    Solar Rad Temperature Increases Higher Greenhouse Effect CO2, CH4 and Water Vapor increases Ice becomes water Absorbs more solar energy POSITIVE FEEDBACK POSITIVE FEEDBACK
  • 45.  
  • 46. where X is ice mass , Y is ocean temperature Z is CO 2 NON-LINEARITY & CHAOS
  • 47.  
  • 48. Complacent Attitude
  • 49. From Union of Concerned Scientists
  • 50. Sarmiento & Gruber 2002 Atmospheric CO 2 concentrations for the last millennium
  • 51.  
  • 52.  
  • 53.  
  • 54.
    • The increase in CO 2 will amplified many times by postive feedbacks
    CO 2 Temperature Increases Higher Greenhouse Effect Water Vapor increases Ice becomes water Absorbs more solar energy POSITIVE FEEDBACKS POSITIVE FEEDBACK
  • 55. Before 1970 , both natural and human factors could have played a role
  • 56. The embedded systems VC by Florian Boor has been shifted to Hall 3 ICSR and will go on in the
  • 57.  
  • 58.  
  • 59.  
  • 60.  
  • 61.  
  • 62. FINGERPRINT OF ANTHROPOGENIC GREENHOUSE EFFECT
  • 63. Satellite Records Show Stratospheric Cooling and Warming!
  • 64.  
  • 65. Backlund et al in “U.S.Climate Change Program”
  • 66.  
  • 67. The Global Carbon Cycle Humans Land 2000 ~90 ~120 ~120 7 GtC/yr ~90 About half the CO 2 released by humans is absorbed by oceans and land Atmosphere 760 + 3/yr Ocean 38,000
  • 68. “ Suess Effect” The decline of C14 after the nuclear tests demonstrates that CO2 entering the atmosphere through fossil fuel use
  • 69.  
  • 70. Over the last 25 years, Gangotri glacier has retreated more than 850 meters
  • 71.  
  • 72.
    • How can we predict the future climate of the Earth ?
  • 73. General Circulation Models (GCMs)
  • 74. Source: Jerry Meehl, National Center for Atmospheric Research
  • 75. from www.realclimate.org
  • 76. Source: National Center for Atmospheric Research The planet is committed to a warming over the next 50 years regardless of political decisions Adaptation Necessary Mitigation Possible
  • 77.  
  • 78.
    • Widespread increase in extreme temperatures and rainfall
    • Cold days, cold nights and frost will be less frequent
    • Hot days, hot nights, and heat waves will be more frequent
    Models predict increase in extremes
  • 79.  
  • 80. Heavy rainfall events (>10cm) Very heavy rainfall events (>15cm) Heavy precipitation events over Central India have increased during last 50 years Source: IITM, Goswami et al. 2006; data is the frequency in each of 143 grids in the region Light to moderate rainfall events (5-100 mm)
  • 81. JJA RAINFALL CHANGE (%) {2080-99 } – {1980-99} NUMBER OF MODELS THAT PREDICT AN INCREASE IN RAINFALL HOW WILL THE MONSOON ( JUNE,JULY AUGUST) RAINFALL CHANGE IN THE FUTURE ?
  • 82. Courtesy: Courtesy: Katharine Hayhoe, Texas Tech University
  • 83. .
  • 84. © 2008 Sustainability Institute Summer Sea Ice in the Arctic 2008 2007
  • 85.  
  • 86.  
  • 87. Lawrence and Slater 2005
  • 88. Tide Gauge Observations Average Rate ~ 1.8 mm/year 0.8 mm/year 2.0 mm/year 3.2 mm/year [Church and White, 2006]
  • 89. Methane Release from Arctic Lakes Burning methane over in Siberia (K. Walter) Methane bubbles trapped in lake ice Lakes boiling with methane in the Arctic
  • 90.  
  • 91.  
  • 92.  
  • 93.  
  • 94.  
  • 95. Impact of glacier melting on sea level 0.5m 7m 57m Courtesy: SCAR
  • 96.  
  • 97.  
  • 98. Millions at Risk from Parry et al., 2001
  • 99. Tipping elements Processes, particularly sensitive to climate change Arctic sea ice melting Deep water formation Antarctic ozone hole West Antarctic ice sheet Amazon vegetation Marine carbon cycle Indian monsoon Sahara El Niño Southern Oscillation Himalaya snow cover Methane outgasing Arctic ozone depletion Greenland ice sheet
  • 100. Transition in Monsoon occurs within 25 years ! Burns et al. (2003) Science 301: 1365-1367 Socotra Island (12°30’ N 54°E) Indian Ocean cave stalagmite proxy for monsoonal precipitation Greenland ice core proxy for local temperature
  • 101. Ocean Conveyor Belt Adapted from IPCC SYR Figure 4-2
  • 102. GEOENGINEERING
  • 103. Rockström et al, Nature 24 Sep 2009
  • 104. 9 PLANTERY BOUNDARIES Transgressing one or more planetary boundaries may be deleterious or even catastrophic due to the risk of crossing thresholds that will trigger non-linear, abrupt environmental change within continental- to planetary-scale systems.
  • 105.  
  • 106. Deutsches Museum (2003) RENEWABLE ENERGY TECHNOLOGY
  • 107. Conclusions
    • Climate Changes before 20 th century on account of natural causes
    • Global warming in 20 th & 21 st century
    • primarily on account of human beings
    • No sense of urgency because it is gradual
    • There can be nasty surprises
    • No catastrophic impact like Ozone hole yet
    • Engineers need to be creative and innovative to ensure transition to an economy based on renewable energy
  • 108.
    • THANK YOU
    • I AM READY
    • FOR
    • A BARRAGE OF QUESTIONS
  • 109.  
  • 110. Risk of overshooting 2 º C target Source: den Elzen and Meinshausen
  • 111.  
  • 112. Deforestation
  • 113.  
  • 114.  
  • 115. From Anthes et al(2005)
  • 116. From Giorgi , ICTP, Trieste
  • 117.  
  • 118. Global Mean Surface Temperature CRU
  • 119. From Ben Santer
  • 120.  
  • 121. Deglaciation
  • 122. Trends in Indian Monsoon Rainfall % change in 100 years, IITM,Pune