I guess it all depends on how “realistic” vs “stylized” you want to make the glass sphere.
Quick, cheap and easy in Zawwerks would be to;
Import a suitable map of the earth into the timeline and turn off its visibility.
Create a solid layer in After Effects and apply the Invigorator effect to it.
A dialog box will appear; make a spherical primative.
Assign the map layer to one of the Layer Maps.
Apply one of the glass presets to the sphere.
Replace the color of the glass preset with the layer map of the map of the earth.
This will give you a “nice” but stylized glass sphere.
You may also want to import and replace the reflaction map of the glass with whatever footage you’re using as a background that the shpere is going to sit on top of. The “stock” reflaction map is just a high contrast series of swirls and replacing that will make the sphere look like it’s reflecting its surrounding better.
If your After Effect artist has worked with Zax before, this should be fairly trivial. If not, there might be a bit of a learning curve, but shouldn’t take more than a few minutes to figure out.