Document ID: ./input/supremecourt_opinions/opinions/06pdf/05-1120.pdf
Page Number: 60

Cite as:  549 U. S. ____ (2007) 

7 

SCALIA, J., dissenting 

mospheric concentrations of [GHGs] and aerosols and
(2) the so-called “feedbacks” that determine the sensi-
tivity of the climate system to a prescribed increase in 
[GHGs].’  Id. 

“The  science  of  climate  change  is  extraordinarily 
complex and still evolving.  Although there have been
substantial advances in climate change science, there 
continue  to  be  important  uncertainties  in  our  under-
standing of the factors that may affect future climate
change and how it should be addressed.  As the NRC 
explained, predicting  future  climate  change  necessar-
ily  involves  a  complex  web  of  economic  and  physical
factors  including:  Our  ability  to  predict  future  global
anthropogenic  emissions  of  GHGs  and  aerosols;  the
fate  of  these  emissions  once  they  enter  the  atmos-
phere  (e.g.,  what  percentage  are  absorbed  by  vegeta-
tion  or  are  taken  up  by  the  oceans);  the  impact  of
those emissions that remain in the atmosphere on the
radiative  properties  of  the  atmosphere;  changes  in 
critically important climate feedbacks (e.g., changes in
cloud  cover  and  ocean  circulation);  changes  in  tem-
perature  characteristics  (e.g.,  average  temperatures,
shifts in daytime and evening temperatures); changes
in  other  climatic  parameters  (e.g.,  shifts  in  precipita-
tion,  storms);  and  ultimately  the  impact  of  such 
changes on human health and welfare (e.g., increases 
or  decreases  in  agricultural  productivity,  human 
health  impacts).  The  NRC  noted,  in  particular,  that 
‘[t]he  understanding  of  the  relationships  between 
weather/climate  and  human  health  is  in  its  infancy 
and  therefore  the  health  consequences  of  climate 
change  are  poorly  understood’  (p.  20).    Substantial 
scientific uncertainties limit our ability to assess each
of these factors and to separate out those changes re-
sulting  from  natural  variability  from  those  that  are
directly  the  result  of  increases  in  anthropogenic