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Monday, February 24, 2020

Worst case CO2 emissions growth scenario is finally losing favor

Last month
two scientists 
published a 
commentary 
in Nature 
magazine, 
calling out 
their fellow
climate modelers
for repeatedly 
exaggerating 
the likelihood 
of catastrophe, 
by exaggerating 
likely future 
greenhouse gas 
emissions. 


The comment 
specifically 
questioned 
the use of 
the Representative 
Carbon Pathways'
         ( RCP ) 
worst-case scenario 
model, RCP8.5.

RCP8.5 had been cited 
more than 2,500 times 
in scientific journals 
as the primary need 
for "urgent action" 
on climate.  

In the original 
scientific paper, 
RCP8.5 had 
a slim 3% chance 
of becoming 
reality.  

Climate alarmists 
loved ECP8.5, 
and called it 
"business-as-usual" 
scenario, even though 
it was not.

Climate scientist 
Zeke Hausfather, of the 
Breakthrough Institute, 
said the RCP8.5 
worst-case scenario
is unlikely to happen.  

We can't get there, 
given how much 
fossil fuel 
is being used now.  

The RCP8.5 model 
assumes a 500% 
increase in the use 
of coal, even though 
actual coal use 
has been declining.

The two authors 
of the Nature article 
hedge by saying 
that lower future 
temperatures, due to 
assuming less coal
use than RCP8.5,
are not guaranteed. 


RCP  BACKGROUND:
Over a decade ago,
the UN's IPCC 
developed four 
scenarios for
future greenhouse 
gas concentrations,
allowing the 
climate modelers
to wild guess 
21st century
global average 
temperatures.

Representative 
Concentration 
Pathways (RCPs) 
ranged from 
RCP2.6 
( smallest change, 
least warming ), 
RCP4.5, 
RCP6.0 and 
RCP8.5. 

The RCP8.5 
scenario was 
a speculative 
worst-case 
scenario.

RCP2.6 assumes 
the Paris Accord 
is implemented.

In 2013 
the IPCC decided
to declare the RCP8.5 
scenario was most likely 
a “Business-as-usual” 
outcome, which then
became popular for 
climate research.

Actual CO2 levels
over recent decades, 
compared to the 
RCP scenarios, 
have been in the 
bottom end of the 
scenario range. 

The authors 
of the Nature 
commentary 
insist
“this admission
[ about exaggerating 
CO2 emissions ] 
does not make 
climate action 
less urgent.” 

They are lying.

Stop the
exaggerating 
of future CO2
emissions,
and then 
climate action
is not urgent 
at all !