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2/6/14 1 GEOG 401 Climate Change Discussion of Readings Earth’s Energy Balance Changing Atmosphere Discussion Readings 1. Diagnosis Earth: The Climate Change Debate, by William Anderegg 2. The Silver Bullet of Climate Change Policy 3. Climate Change: Who’s the biggest emiMer of them all?
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GEOG 401 Discussion - Earth Energy Balance - Changing ...climate.socialsciences.hawaii.edu/Courses/GEOG401/GEOG 401 Discussion... · 2/6/14 7 Energy&Balance&of&PlanetEarth&...

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  • 2/6/14  

    1  

    GEOG  401  Climate  Change  

    Discussion  of  Readings  Earth’s  Energy  Balance  Changing  Atmosphere  

    Discussion  

    Readings  1.  Diagnosis  Earth:  The  Climate  Change  Debate,  by  William  

    Anderegg  2.  The  Silver  Bullet  of  Climate  Change  Policy  3.  Climate  Change:  Who’s  the  biggest  emiMer  of  them  all?  

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    Diagnosis  Earth:  The  Climate  Change  Debate,  by  William  Anderegg  

    •  What  problem  was  invesPgated  in  the  study  reported  here?  •  What  methodology  was  used?  •  What  were  the  results?  •  What  are  the  implicaPons  of  those  results?  •  Were  there  any  significant  flaws  in  the  methodology  that  

    might  have  biased  the  results?  •  When  the  corporate  media  presents  the  issue  of  climate  

    change,  do  you  think  they  fairly  represent  the  scienPfic  consensus  on  global  warming?  

     

    The  Silver  Bullet  of  Climate  Change  Policy  

    •  What  problem  does  this  arPcle  address?  •  What  is  the  “silver  bullet  of  climate  change  policy  according  

    to  this  arPcle?  •  Do  you  agree  or  disagree  with  the  conclusions  of  this  arPcle?  

     

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    Climate  Change:  Who’s  the  biggest  emiMer  of  them  all?  

    •  What  problem  does  this  arPcle  address?  •  Who  are  the  biggest  emiMers?  •  What  is  the  fairest  way  to  allocate  the  costs  of  addressing  

    climate  change?  

     

    Energy  Balance  of  Planet  Earth  

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    Energy  Balance  of  Planet  Earth  Intercepted  Solar  Energy  =  solar  constant  x  disk  area  of  Earth  Intercepted  Solar  Energy  =  1366  [W  m-‐2]  x  πr2  [m2]  Radius  of  Earth  =  6,378,100  meters  Intercepted  Solar  Energy  =  1.74575  x  1017  WaMs  

    Energy  Balance  of  Planet  Earth  

    Intercepted  Solar  Energy  Averaged  Over  the  Whole  Earth    =  Intercepted  Solar  Energy  ÷  Surface  Area  of  Earth    =  1366  [W  m-‐2]  x  πr2  [m2]  ÷  4  πr2  [m2]      =  1366/4  [W  m-‐2]      =  341.5  W  m-‐2  

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    Energy  Balance  of  Planet  Earth  Absorbed  Solar  Energy  Averaged  Over  the  Whole  Earth    =  Intercepted  Solar  Energy  x  (1  –  Earth  Albedo)  Earth  Albedo  =  0.3  Absorbed  Solar  Energy  =  341.5  x  0.7  [W  m-‐2]    Absorbed  Solar  Energy  =  239  W  m-‐2    

    Energy  Balance  of  Planet  Earth  To  maintain  energy  equilibrium,  the  Earth  must  emit  an  amount  of  longwave  radiaAon  equal  to  the  absorbed  solar  energy.    Earth  Longwave  EmiDed  RadiaAon    =  Absorbed  Solar  Energy    =  239  W  m-‐2    

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    Energy  Balance  of  Planet  Earth  What  is  the  mean  equilibrium  temperature  of  the  Earth?  

    Use  the  Stefan-‐Boltzmann  equaPon:  

    Rearranging  I  =  σT4  we  get:  

    T  =  (I/σ)0.25      

    T  =  (239  /  5.67  x  10-‐8)0.25  

    =  254.8  K    

    =  -‐18.3°C    

    -‐18.3°C  ß  RadiaAve  Equilibrium  Temperature  of  Earth  

    Energy  Balance  of  Planet  Earth  RadiaAve  Equilibrium  Temperature  of  Earth  =  -‐18.3°C    

    Actual  mean  surface  temperature  of  earth:  

    20th  Century  Mean:  13.9°C  (57.0°F)  

    2012  Mean:  14.5°C  (58.03°F)  

    QuesAon  1:  Why  is  the  actual  surface  temperature  32.8°C  higher  than  the  radiaPve  equilibrium  temperature?  

    QuesAon  2:  Is  the  radiaPve  equilibrium  temperature  of  the  earth  changing  due  to  increasing  greenhouse  gases?  

    QuesAon  3:  Why  is  the  surface  temperature  of  the  earth  increasing?  

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    Energy  Balance  of  Planet  Earth        On  the  following  slide  is  a  diagram  showing  the  present-‐day,  globally-‐averaged  verAcal  energy  fluxes  for  planet  earth.  Look  carefully  at  the  diagram  and  answer  these  quesAons:    

    QuesAon  1:  How  much  energy  is  entering  at  the  earth  system  at  the  “top  of  the  atmosphere”  (TOA)?  Use  the  mean  esPmates.  

    QuesAon  2:  How  much  energy  is  leaving  at  the  TOA?  

    QuesAon  3:  Are  the  incoming  and  outgoing  energy  at  the  TOA  equal?  

    QuesAon  4:  Do  the  same  comparison  for  (a)  the  atmosphere,  and  (b)  the  earth’s  surface.  Do  the  comparison  using  radiaPon  only  and  then  do  it  using  all  energy  fluxes.  

    QuesAon  5:  What  will  happen  to  this  picture  if  greenhouse  gas  concentraPons  (a)  keep  on  increasing;  (b)  level  off;  (c)  decline?  

    Energy  Balance  of  Planet  Earth  

    AR5  WG1  Drap  report  (2013,  Chapter  2)  

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    Changing  Atmosphere  

    AR5  WG1  Drap  report  (2013,  Chapter  2)  

    Changing  Atmosphere  

    AR5  WG1  Drap  report  (2013,  Chapter  2)  

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    Changing  Atmosphere  

    AR5  WG1  Drap  report  (2013,  Chapter  2)  

    Changing  Atmosphere  

    AR5  WG1  Drap  report  (2013,  Chapter  2)  

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    Changing  Atmosphere  

    AR5  WG1  Drap  report  (2013,  Chapter  2)  

    Changing  Atmosphere  

    AR5  WG1  Drap  report  (2013,  Chapter  2)  

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    Changing  Atmosphere  

    AR5  WG1  Drap  report  (2013,  Chapter  2)  

    Changing  Atmosphere  

    AR5  WG1  Drap  report  (2013,  Chapter  2)  

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    Changing  Atmosphere  

    AR5  WG1  Drap  report  (2013,  Chapter  2)  

    Changing  Atmosphere  

    AR5  WG1  Drap  report  (2013,  Chapter  2)  

    LSAT  Land  Surface  Air  Temperature  

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    Changing  Atmosphere  

    AR5  WG1  Drap  report  (2013,  Chapter  2)  

    SST  Sea  Surface  Temperature  

    NMAT  Night  Marine  Air  Temperature  

     

    Changing  Atmosphere  

    AR5  WG1  Drap  report  (2013,  Chapter  2)  

    SST  Sea  Surface  Temperature  

    From  Satellites  and  in  situ  records