Dear Uzair,

CMIP5 uses a different approach for scenarios than CMIP3.  For this reason there is not a one-to-one correspondence between scenarios in CMIP5 and those in CMIP3. 

In terms of CO2-equivalent concentrations reached by the year 2100, the RCP8.5 scenario of CMIP5 is similar to the A1FI scenario of CMIP3; the RCP6.0 scenario of CMIP5 is between the A1B and B2 scenarios of CMIP3; and RCP4.5 of CMIP5 is similar to B1 of CMIP3.  Again, keep in mind that these are only rough estimations.

I hope this is useful for you.

Regards
Ray Arritt

 
On 1/1/2014 6:25 AM, uzair manan wrote: