How  we  know  what  we  know:  Advancing  climate  change  education  

 

Nicole  Holthuis,  Andrew  Wild,  Rachel  Lotan,    

Jennifer  Saltzman,  and  Mike  Mastrandrea  

 

Abstract  

Climate  change  is  one  of  the  most  complex  scientific  and  social  challenges  we  face  today.  

Learning  about  climate  change  offers  rich  opportunities  for  students  to  learn  both  what  we  

know  about  the  causes  and  effects  of  climate  change  and  how  we  know  what  we  know.    In  

this  article,  we  describe  what  we  learned  from  working  with  middle  and  high-­‐school  

science  teachers  as  they  taught  a  unit  about  climate  change  in  their  classrooms.    We  

provide  examples  of  curricular  activities  that  facilitate  students’  understanding  of  the  tools  

used  to  collect  climate  change  data,  support  their  construction  of  arguments,  and  help  them  

grasp  characteristics  of  scientific  theories.    By  doing  so,  climate  change  education  provides  

an  excellent  opportunity  for  students  to  connect  science  content,  scientific  practices,  and  

the  nature  of  scientific  knowledge,  as  advocated  for  by  the  Next  Generation  Science  

Standards.  

 

Introduction  

Climate  change  is  one  of  the  most  complex  scientific  and  social  challenges  we  face  today.    It  

is  also  one  of  the  most  complex  topics  to  teach.    It  is  politically-­‐laden  and  perceived  as  

controversial,  at  least  in  part,  because  of  the  coverage  of  climate  change  "deniers"  and  the  

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media  attention.    But  unlike  some  other  controversial  topics  in  science,  it  also  has  

immediate  implications  for  contemporary  human  behaviors  and  societal  practices.        

As  the  field  has  developed,  educators  and  scientists  have  come  to  understand  that  a  deficit  

model  of  knowledge  doesn’t  explain  why  people  continue  to  disagree  about  climate  change.    

Our  team  of  science  educators,  teachers,  and  climate  scientists  at  the  XXXXX  Climate  

Change  Education  Project  developed  curriculum  materials  that  advance  students'  ability  to  

separate  scientific  evidence  from  beliefs  and  values,  making  them  critical  consumers  of  

information.    This  curriculum  provides  students  with  opportunities  to  grapple  with  what  

we  know  about  climate  change  and  how  we  know  it.    In  doing  so,  scientific  content  and  

practices  identified  by  the  Next  Generation  Science  Standards  (NGSS  Lead  States,  2013)  

become  inextricably  linked  (Figure  1).    

Disciplinary  Core  Ideas  • ESS2.D:    Changes  in  the  atmosphere  due  to  human  activity  have  increased  carbon  dioxide  

concentrations  and  thus  affect  climate.  (HS-­‐ESS2-­‐6),(HS-­‐ESS2-­‐4)  • ESS3.D:  Though  the  magnitudes  of  human  impacts  are  greater  than  they  have  ever  been,  so  too  are  

human  abilities  to  model,  predict,  and  manage  current  and  future  impacts.  (HS-­‐ESS3-­‐5)    Science  and  Engineering  Practices  • Construct  an  explanation  based  on  valid  and  reliable  evidence  obtained  from  a  variety  of  sources  

(including  students’  own  investigations,  models,  theories,  simulations,  peer  review)  and  the  assumptions  that  theories  and  laws  that  describe  the  nature  world  operate  today  as  they  did  in  the  past  and  will  continue  to  do  in  the  future.  (HS-­‐ESS3-­‐1)  

• Construct  an  oral  and  written  argument  or  counter  arguments  based  on  data  and  evidence  (HS-­‐ESS2-­‐7)  

 Connections  to  Nature  of  Science  • Scientific  investigations  use  diverse  methods  and  do  not  always  use  the  same  set  of  procedures  to  

obtain  data.    • New  technologies  advance  scientific  knowledge.    • Scientific  knowledge  is  based  on  empirical  evidence.  • Scientific  arguments  are  strengthened  by  multiple  lines  of  evidence  supporting  a  single  explanation.    

Figure  1:    Connections  to  the  core  ideas,  scientific  practices,  and  nature  of  science  as  described  in  the  Next  Generation  Science  Standards  

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What  does  this  look  and  sound  like  in  the  classroom?    In  this  article,  we  describe  what  we  

learned  from  working  with  thirty-­‐seven  middle  and  high-­‐school  science  teachers  across  the  

San  Francisco  Bay  Area,  as  they  taught  the  XXXX  Climate  Change  Curriculum  

(climatechange.XXXX.edu)  in  their  classrooms.    We  focus  on  three  questions  that  teachers  

explored  with  their  students:    1)  Where  does  climate  change  data  come  from  and  how  is  it  

collected?    2)  What  conclusions  can,  and  cannot,  be  made  from  these  data?  and  3)  How  has  

our  understanding  of  climate  change  developed  over  time  from  making  claims  to  building  

theories?    By  examining  these  important  questions,  climate  change  education  provides  an  

excellent  opportunity  for  students  to  connect  science  content,  scientific  practices,  and  the  

nature  of  scientific  knowledge,  as  advocated  for  by  the  Next  Generation  Science  Standards.  

 

Where  does  evidence  come  from?  

Scientists  tell  us  that  the  average  global  temperature  and  atmospheric  CO2  levels  are  at  

their  highest  level  in  over  450,000  years  (Figure  2).      But,  thermometers  were  not  invented  

until  1724.      

 

 

 

 

 

 

 

 Figure  2:    CO2  level  and  Temperature  450,000  years  ago  to  present.  Reprinted  from  Let’s  face  the  truth  about  climate  change  mitigation  (I)  by  julienx2k2,  2007,  Retrieved  November  30,  2013,  from  blaskarm.wordpress.com/2007/09/14/lets-­‐face-­‐the-­‐truth-­‐about-­‐climate-­‐change-­‐mitigation-­‐i/.  Original  data:  Petit  J.R.,  Jouzel  J.,  Raynaud  D.,  Barkov  N.I.,    Barnola  J.M.,  Basile  I.,  Bender  M.,  Chappellaz  J.,  Davis  J.,  Delaygue  G.,    Delmotte  M.,  Kotlyakov  V.M.,  Legrand  M.,  Lipenkov  V.,  Lorius  C.,    Pépin  L.,  Ritz  C.,  Saltzman  E.,  Stievenard  M.,  1999,    Climate  and  Atmospheric  History  of  the  Past  420,000  years  from  the    Vostok  Ice  Core,  Antarctica,  Nature,  399,  pp.429-­‐436.  

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So  how  do  we  know?    Where  does  the  

evidence  come  from?      

One  powerful  source  of  data  comes  from  

ice  cores.    Drilling  into  ice  sheets  in  

Greenland  and  Antarctica  allows  us  to  

measure  the  atmospheric  conditions  of  

the  past.    Each  winter  new  snow  falls  on  top  of  previously  un-­‐melted  snow.    This  process  

creates  distinct  layers  of  ice  each  year;  summer  ice  

appears  light  while  winter  ice  appears  dark.      By  

drilling  thousands  of  feet  deep,  researchers  extract  

cores  of  ice  formed  hundreds  of  thousands  of  years  

ago.    Air  bubbles  are  trapped  in  the  ice  as  it  is  

formed.  Analysis  of  the  trapped  gases  and  the  

chemical  composition  of  the  ice  itself  helps  scientist  

know  what  the  climate  was  like  thousands  of  years  

ago.    The  most  famous  site  where  data  are  found  is  

in  Vostok,  a  Russian  station  near  the  South  Pole.    

 

 

We  observed  classrooms  as  students  learned  about  ice  cores.    One  teacher  had  students  

create  their  own  “ice  core  strips.    Students  counted  and  labeled  the  number  of  seasons  

Figure  3:    Scientist  and  ice  core.  Reprinted  from  Ice  Core  Drills,  2010,  Retrieved  October  2,  2013,  from  http://www.icedrill.ch/.  Copyright  2007  by  Dieter  Stampfli.  Reprinted  with  permission.  

Figure  4:  Ice  core  from  a  depth  of  1855  m.  Reprinted  from  Paleo  Slide  Set:  Polar  Ice  Cores  by  A.  Gow,  2001,  Retrieved  November  30,  2013  from  http://www.ncdc.noaa.gov/paleo/slides/slideset/15/15_281_slide.html.  Public  image.  

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represented.    Then  each  band  was  assigned  a  temperature  based  on  a  simulated  gas  

analysis  of  that  band.    Students  graphed  the  temperature  data  over  time.    As  students  

discussed  the  Vostok  ice  core  data,  they  came  to  realize  that  while  the  Earth  has  

experienced  natural  heating  and  cooling  cycles  in  concert  with  variations  in  greenhouse  

gas  levels  in  the  atmosphere,  more  current  measurements  show  a  fundamentally  different  

pattern.      

 

Scientists  have  compared  ice  core  and  other  proxy  data  with  direct  measurements  of  CO2  

from  the  past  several  decades.    Comparing  these  data  indicates  that  the  current  CO2  levels  

are  higher  now  than  they  have  been  for  at  least  800,000  years,  with  a  sharp  rise  in  CO2  

since  the  Industrial  Revolution  (mid-­‐1700s).  Detailed  estimates  of  CO2  sources  and  sinks  

provide  clear  evidence  that  CO2  levels  are  increasing  as  a  result  of  human  activities.    

 

From  evidence  to  claims  

As  noted  in  the  NGSS  (2013),  data  and  evidence  are  the  foundation  for  developing  claims.    

The  wealth  of  climate  change  data—both  raw  and  processed—provides  unique  

opportunities  for  students  to  synthesize  and  analyze  data  in  order  to  make  sense  of  it  and  

to  come  to  some  conclusions.    Thus,  the  curriculum  materials  were  designed  around  six  

objectives,  one  of  which  states:  “Students  will  use  data  and  evidence  to  justify  claims  

relating  to  climate,  climate  change,  and  mitigation.”    

 

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Teachers  often  began  the  unit  by  asking  students  to  

consider  how  we  know  what  we  know.    Teachers  

framed  this  question  of  “how  we  know”  in  many  ways  

(see  Figure  5).      

Ms.  X  presented  the  Mauna  Loa  graph  

(Figure  6)  to  her  students.    “What  do  you  

make  of  this  graph?”  she  asked.    Students  

discussed  in  pairs  what  the  data  suggested  

and  what  they  could  conclude  from  it.    

“Carbon  dioxide  emissions  are  going  up,”  

responded  one  student.    

 

 

In  another  class,  after  a  student  stated  incorrectly  that  greenhouse  gases  were  the  most  

abundant  gases  in  the  atmosphere,  the  teacher  took  the  opportunity  to  pose  another  

question:  “How  do  you  know  that  greenhouse  gases  are  the  most  abundant?”  By  

structuring  the  questions  in  this  way,  she  was  no  longer  the  ultimate  authority,  the  evidence  

was.    As  the  student  began  to  talk  through  the  data  on  the  board,  he  came  to  realize  that  the  

data  contradicted  his  claim.    This  provided  him  the  opportunity  to  improve  in  his  ability  to  

support  a  claim  with  evidence.  The  teacher  also  set  an  expectation:  if  you  make  a  scientific  

claim,  you  must  have  evidence  to  support  it.      

 

Figure  6:    Graph  discussed  in  Teacher  H1  Class.  Atmospheric  Carbon  Dioxide.  Reprinted  from  Wikipedia  Commons  -­‐  "Atmospheric  Carbon  Dioxide”  by  R.  A.  Rohde,  2008,  Retrieved  November  30,  2013  from  http://commons.  wikimedia.org/wiki/File:Mauna_Loa_Carbon_Dioxide-­‐en.svg.  Public  image.  

• How do we know that? • Scientists didn’t always know _____. • How certain are we/scientists about that? • What makes you think that? • What’s your evidence? • How would you know if you were wrong? • How did you arrive at that conclusion?

Figure  5:    Questions  to  Promote  “How  do  we  know”  Talk  in  the  classroom  

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Students  worked  in  small  groups  to  practice  making  claims  and  supporting  them  with  

evidence.    For  example,  in  one  science  class,  four  students  were  examining  a  graph  (Figure  

7)  that  showed  the  predicted  “magnitude  of  

adverse  impact”  on  various  natural  

ecosystems  given  an  increase  in  

temperature  between  0  and  4  degrees  

Celsius.  One  group  member  made  a  claim  

that  the  magnitude  of  impact  goes  up  over  

time  (recently  versus  later).  Another  student  pointed  out  that  “it  doesn’t  really  say  timeline.  

It  says  ‘Celsius’.”  They  then  revised  their  claim:  “A  temperature  change  of  4°  Celsius  would  

badly  change  the  environment.”    

 

To  support  students  as  they  gain  and  enhance  their  ability  to  formulate  solid  scientific  

claims,  teachers  can  model,  make  explicit  references  to,  and  label  the  distinct  features  of  a  

scientific  argument.    In  one  class,  students  discussed  the  evidence  for  climate  change  

presented  in  a  somewhat  complex  graph.    After  a  discussion  of  the  graph,  the  teacher  

summarized:    “So  that  is  a  good  statement  of  evidence,  right?    I’ve  said  what  my  graph  

shows,  I’ve  talked  about  what  the  trend  is….I’ve  told  you  what  years  I  was  looking  at.    So,  

when  [you]  present  evidence,  that’s  the  kind  of  statement  that  I’m  looking  for.    I  want  a  

very  concrete  statement  that  has  all  of  those  pieces,  if  possible.”    This  type  of  meta-­‐talk  

provides  students  opportunities  to  realize  how  scientific  understanding  may  differ  from  

the  everyday  conclusions  or  colloquial  ways  of  talking  about  data  and  claims.    It  promotes  

specialized  science  discourse  in  the  classroom.      

Figure  7:    Impact  of  Climate  Change  on  Natural  Ecosystems  

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From  claims  to  theories  

 

Science  textbooks  often  portray  a  world  of  firm  conclusions,  with  the  underlying  evidence  

occasionally  acknowledged  (Bowen  &  Roger  2008;  Roth,  Bowen  &  McGinn  1999).      As  a  

result,  Hodson  (1998)  argues,  students  may  begin  to  think  that  theories  are  formulated  

from  a  few  bits  of  evidence  and,  conversely,  are  abandoned  because  of  a  few  negative  

results.      In  reality,  “theories  are  only  abandoned  when  there  is  compelling  evidence  (long-­‐

standing  and  striking  at  the  fundamental  core  of  the  theory)….In  practice,  all  theories  have  

to  live  with  anomalous  data;  it  is  a  natural  feature  of  science.”    (p.  194)    Moreover,  

argumentation,  not  dismissal  of  the  previously  established  theory,  is  the  process  by  which  

scientists  evaluate  and  critique  the  evidence  and  its  coordination  with  theory.  When  it  

comes  to  climate  change,  misunderstandings  about  the  nature  of  scientific  knowledge  lead  

to  some  of  the  faulty  arguments  used  to  deny  the  existence  of  anthropogenic  climate  

change.    

 

In  one  class,  the  teacher  examined  with  her  students  how  our  understanding  of  climate  

systems  and  climate  change  has  developed  and  changed  over  time.    In  ancient  times,  people  

began  to  suspect  that  a  region’s  climate  could  change  over  a  long  period.    In  the  18th  and  

19th  centuries,  people  began  to  observe,  in  a  single  life-­‐time,  how  human  activity  can  alter  

the  environment,  though  few  believed  humans  could  actually  alter  the  climate  of  the  planet  

as  a  whole.  

 

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Then  in,  1827,  Joseph  Fourier  published  work  in  which  he  postulated  that  the  Earth’s  

atmosphere  kept  the  planet  warmer  than  it  would  be  if  the  planet  existed  in  a  vacuum.  He  

also  suspected  that  changes  in  human  activity  and  natural  forces  could  actually  change  the  

Earth’s  climate  over  long  periods  of  time.    In  1896,  Swedish  scientist  Svante  Arrhenius  

published  calculations  predicting  that  the  planet’s  average  temperature  would  increase  as  

humanity  burned  fossil  fuels  such  as  coal.    Many  rejected  his  claim  thinking  that  humanity  

could  never  affect  the  vast  climate  cycles.      This  was  the  beginning  of  a  more  than  100-­‐year  

history  of  ever-­‐more  careful  measurements  and  calculations  to  pin  down  exactly  how  

greenhouse  gas  emissions  and  other  factors  influence  Earth’s  climate  (Weart  2008).    By  the  

1950s,  a  growing  number  of  scientists  were  concerned  that  carbon  dioxide  emissions  

would  lead  to  an  increase  in  the  Earth’s  temperature.    In  1960,  Charles  Keeling  documented  

that  the  level  of  CO2  in  the  atmosphere  was  in  fact  rising.  Concern  mounted  year  by  year  

along  with  the  rise  of  the  “Keeling  Curve”  of  atmospheric  CO2  (Keeling  and  Whorf  2004).  

 

Scientists’  understanding  of  climate  change  has  increased,  as  has  their  certainty  about  what  

is  happening.      Yet,  scientific  certainty  and  uncertainty  is  a  widely  misunderstood  concept.    

We  observed  teachers  and  students  as  they  examined  how  and  why  our  certainty  about  

climate  change  has  changed  over  time.  In  a  tenth  grade  classroom,  students  were  working  

in  a  group,  examining  global  land-­‐ocean  temperature  records  (see  Figure  8).    One  group  

member  stopped  the  teacher  to  ask:  

 

S1:    Ms.  J,  what’s  the  green  line?  

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T:       The  green  is  something  that  you  

may  or  may  not  have  heard  of  

before…  It’s  just  looking  at  our  

level  of  uncertainty  or  possible  

errors  within  our  data.    So,  as  

time  progresses,  what  happens  

to  that  green  bar?    Does  it  get  

longer  or  shorter?  

S1:     Smaller.  

T:     It  gets  shorter.    So,  what  would  

that  tell  us?  Could  there  be  more  room  for  error?  

S1:     Less  error.  

T:     Less  room  for  error.  Right?  

S2:    Because  we  have  more  data?    Technology  is  better?  

T:     Both  reasons,  yeah.    So,  back  here,  you  know,  we  had  some  good…  we  had  some  means  

of  measurement  but  it  wasn’t  the  best  technology.  

 

This  example  illustrates  ways  in  which  teachers  and  students  might  discuss  uncertainty-­‐-­‐

considering  the  precision  of  measurements  over  time  and  the  distribution  of  those  

measurements  around  the  world,  for  example.  1  

  1  For  more  information,  see  Hanson,  J.,  Ruedy,  R.,  Sato,  M.  and  Lo,  K.  (2010)    Global  Surface  Temperature  Change.    Review  of  Geophysics.    48.    

Figure  8:    Graph  discussed  in  the  Ms.  Js  class.  Global  Land-­‐Ocean  Temperature  Index.  Reprinted  from  GISS  Surface-­‐Temperature  Analysis,  2013,  by  National  Aeronautics  and  Space  Administration,  Retrieved  November  30,  2013  from  http://data.giss.nasa.gov/gistemp/graphs_v3/.  Public  image.  

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Conclusion  

Learning  about  climate  change  offers  rich  opportunities  for  students  to  learn  both  what  we  

know  about  the  causes  and  effects  of  climate  change  and  how  we  know  what  we  know.  Since  

fallacious  or  misleading  arguments  about  climate  charge  are  often  rooted  in  

misconceptions  about  the  nature  of  science,  it  is  important  for  students  to  learn  how  

scientific  knowledge  about  climate  change  has  developed.      By  engaging  in  the  practice  of  

argumentation,  students  are  likely  to  develop  a  stronger  conceptual  understanding  of  the  

content,  better  grasp  about  how  scientific  knowledge  is  constructed,  and  the  development  

of  scientific  theories  over  time.      

It  can  be  challenging  and  time-­‐consuming  to  facilitate  students’  understanding  of  the  tools  

used  to  collect  climate  change  data,  support  the  construction  of  arguments,  and  help  them  

grasp  characteristics  of  scientific  theories.    We  have  provided  some  examples  of  what  this  

teaching  and  learning  looks  like  in  practice  and  we  have  offered  some  information  about  

the  nature  of  the  data  and  scientific  theories.  By  teaching  what  we  know  about  climate  

change  science  and  how  we  know  it,  students  have  a  greater  capacity  to  make  scientifically  

informed  decisions  and  to  interpret  climate  change  information  from  a  more  critical  

perspective.    

 

 

References  

Bowen,  G.,  W-­‐M.  Roth,  and  M.  McGinn.  1999.  Interpretations  of  graphs  by  university  biology  students  and  practicing  scientists:  Toward  a  social  practice  view  of  scientific  representation  practices.  Journal  of  Research  in  Science  Teaching  36(9);  1,020-­‐1,043.    

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Bowen,  G.  M.  and  V.  Rodger.    2008.    Debating  global  warming  in  media  discussion  forums:    Strategies  enacted  by  “persistent  deniers”  and  implications  for  schooling.    Canadian  Journal  of  Enviornmental  Education  13(1);  89-­‐106.  

Hodson,  D.  (1998).  Science  fiction:  The  continuing  misrepresentation  of  science  in  the  school  curriculum.  Curriculum  Studies  6(2);  191-­‐216.  

Keeling,  C.  and  Whorf,  T.  (2004).  Atmospheric  CO2  from  continuous  air  samples  at  Mauna  Loa  Observatory,  Hawaii,  U.S.A.    Carbon  Dioxide  Information  Analysis  Center,  Oak  Ridge  National  Laboratory.    NGSS  Lead  States.  2013.    Next  generation  Science  Standards:    For  states,  by  states.    Washington,  DC:    The  National  Academies  Press.    Weart,  S.    2008.    The  Discover  of  Global  Warming.    Boston,  MA:    Harvard  University  Press.