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4 

MASSACHUSETTS v. EPA 

Opinion of the Court 

drafted  §202(a)(1)  in  1970,  carbon  dioxide  levels  had 
reached 325 parts per million.10 

In the late 1970’s, the Federal Government began devot-
ing serious attention to the possibility that carbon dioxide
emissions  associated  with  human  activity  could  provoke 
climate  change.  In  1978,  Congress  enacted  the  National 
Climate  Program  Act,  92  Stat.  601,  which  required  the 
President to establish a program to “assist the Nation and 
the world to understand and respond to natural and man-
induced climate processes and their implications,” id., §3.
President  Carter,  in  turn,  asked  the  National  Research 
Council,  the  working  arm  of  the  National  Academy  of 
Sciences,  to  investigate  the  subject.    The  Council’s  re-
sponse  was  unequivocal:  “If  carbon  dioxide  continues  to 
increase,  the  study  group  finds  no  reason  to  doubt  that 
climate  changes  will  result  and  no  reason  to  believe  that 
these changes will be negligible. . . . A wait-and-see policy 
may mean waiting until it is too late.”11 

Congress  next  addressed  the  issue  in  1987,  when  it
enacted the Global Climate Protection Act, Title XI of Pub. 
L.  100–204,  101  Stat.  1407,  note  following  15  U. S. C. 
§2901.  Finding  that  “manmade  pollution—the  release  of 
carbon  dioxide,  chlorofluorocarbons,  methane,  and  other 
trace  gases  into  the  atmosphere—may  be  producing  a 

—————— 

from  long  ago  and  extract  small  samples  of  ancient  air.    That  air  can 
then be analyzed, yielding estimates of carbon dioxide levels.  Ibid. 

10 A more dramatic rise was yet to come: In 2006, carbon dioxide lev-
els  reached  382  parts  per  million,  see  Dept.  of  Commerce,  National 
Oceanic & Atmospheric Administration, Mauna Loa CO2 Monthly Mean
Data,  www.esrl.noaa.gov/gmd/ccgg/trends/co2_mm_mlo.dat  (all  Internet
materials  as  visited  Mar.  29,  2007,  and  available  in  Clerk  of  Court’s 
case file), a level thought to exceed the concentration of carbon dioxide 
in  the  atmosphere  at  any  point  over  the  past  20-million  years.  See 
Intergovernmental  Panel  on  Climate  Change,  Technical  Summary  of 
Working Group I Report 39 (2001). 

11 Climate Research Board, Carbon Dioxide and Climate: A Scientific 

Assessment, p. vii (1979).