High temperature leading to less snow in the mountains and things like that?
I think (not 100% sure) there is already a really simple version of that, working only for the whole world.
Take a look at user/data/earth/planet.cfg and:
snow = (virtual_elevation) {
virtelev = (float2) {
x = 3500.0,
y = 0.0
},
virtcurv = 2500.0,
snowmin = 4900.0,
snowsat = 6000.0
},
There are two snow levels, applied to the whole world snowmin (min elevation for snow) and snowsat (elevation where the snow cover 100% of the ground). But the others two parameters are used to modulate the two others.
Edit:
snowmin = 1200
As you can see, the low lands of Africa stay clear, but the ones in Europe and South Africa are under snow. Of course the result is weird because it's global and no local climates are in action here.