Halocarbons 0.36 W/m^2
CO2 1.88
Methane 0.49
N20 0.17
Ozone 0.4
Total 3.3
So the 0.3W/m^2 is only about a tenth of GHG forcing (maybe fifth of the warming we see taking areosols as masking half the effect of GHGs).
Warming appears less than 0.2 C per decade so a fifth of that is 0.04C per decade.
In the Arctic, the warming is 2, maybe 3 times higher than global temperatures. It is important differentiate between local and global effects.
Thus 1C per decade appears like 25 times stronger than what we are experiencing. For a 3 times stronger effect (of 0.3W/m^2 vs 0.1), this does not compute.
Albedo forcings are local to the Arctic and only during summer. CO2 forcing is global and uniform throughout the year. However in the Arctic the warming is 2-3 times higher than the global average. Albedo change is just one of the many forcings that are causing the temperature difference. It is a small one relative to others as you well said, however it's influence will increase as extent decreases.
I think the biggest forcing at work is the lack of volume to melt. Because of the enthalpy of fusion of ice a lot of solar energy that would have gone to melt ice now goes to warm the Arctic. The funny thing about that is that it has no bearing on global warming except for the bit that gets irradiated out to space. If anything it cools the globe a bit.
I think the other large forcing is the atmosphere sending heat waves and water vapor into the Arctic. That's another factor that makes no direct difference in global temperatures but make a huge difference in Arctic temperatures.
CO2 is there of course, but it is more powerful as a global influencer of temperatures. Elevated global temperatures eventually lead to more heat into the Arctic, but CO2's direct impact as a greenhouse gas is not as large for Arctic amplification considerations. Methane and water vapor might be a different matter.