Creating buffers using the ArcToolbox Buffer Tool does not create ellipsoids for geographic projected data when data nears the poles. This article contains instructions on how to create ellipsoid buffers for data in a geographic coordinate system.
In ArcMap, navigate to Tools > Customize > Commands tab > select Tools under Categories.
Click and drag the Buffer Wizard to an existing toolbar in the Commands dialog box.
Click the Buffer Wizard icon to set up the buffer and then select Finish.