I think so, but only if you count total warming as overall warming + cooling effects.

The critical numbers, from pages 98 - 100 of the linked report (units = Watts per square metre of earth's surface):

 - The accumulation of energy is driven by a positive total anthropogenic effective radiative forcing (ERF) relative to 1750. The best estimate ERF of 2.72 W m-2
 - The ERF due to methane emissions is 1.21 [0.90 to 1.51] W m–2
 - Aerosols contributed an ERF of –1.3 [–2.0 to –0.6] W m–2 

Note aerosols have a cooling effect, so the sum of warming effects could be said to be 2.72 + 1.3 W = 4.02.  1.21/4.02 = 0.3, which is close enough to the BBC figure to make sense.