Convert from gigatonne to obolus [Ancient Rome]

Unit Definition (gigatonne)
The gigatonne is a metric unit of mass or weight equal to one billion metric tons (tonnes) or about 2.2046 trillion pounds. This very large unit is used, for example, in discussing the amounts of carbon added to the atmosphere by human activities.

Unit Definition (obolus [Ancient Rome])
The obolus [Ancient Rome] is a historic unit of weight or mass. The obol is a very small weight that originated as the weight of a tiny Greek coin. In Rome, the obolus was equal to 1/48 Roman ounce (uncia) or about 0.57 gram.