Best way to deal with overlapping elements

[Azélor]

I was wondering if there was a better way to deal with overlapping categories on thematic maps.

In my example below, I have a map showing the evolution of the tundra biome merging 3 different maps. One is the actual climate of the world representing the average between 1976 and 2000. The other 2 are projections made for 2100 using 2 scenarios. I chose to keep only the extreme ones to show the difference (A1FI and B1). I'm trying to show where the tundra would expand and recede by comparing the 2 scenarios to the present era.

I was wondering if it was easy to understand and if there is a better way to do it. Note that the expanding tundra come from the melting ice sheet of Greenland, otherwise, it's just receding everywhere. In the optimist scenario, Tibet lose almost 70% of it's tundra.

tundra.jpg