Specific Conversion to IGH
The switch to an IGH is never as simple as it looks. There are a couple of things to consider:


Wheel: Yes you will need to have a new wheel built replacing the hub with a IGH hub. You can reuse the rim (if spoke count matches) but will also require new spokes.
Dropouts: The Globe Works 3 has a semi horizontal rear dropout while the Globe Works 2 has a vertical dropout and hanger. Derailleur bikes rely on the RD to tension the chain, IGH relies on placement of the rear hub in relation to the crank, this is where horizontal dropouts work well as you can slide the wheel to the right place. Without these you need a separate chain tensioning device. 
Chain Tensioner: Without horizontal dropouts you need to find a way to ensure chain tension. The most simplest and effective is an eccentric bottom bracket which allows the crank to be reposition slightly to achieve chain tension. Other devices hang in place of the derailleur but add moving and noisy parts.
Crankset: IGH work with a single crankset and fixed chainline. You would need to modify your current crankset to a single ring (if possible), keep the multiple rings only using one or buy a new crankset.
Shifters: IGH use different shifters to derailleurs so you will need to also purchase new shifters.