Antarctica is actually not that difficult. Antarctica is cold because the sea currents around it insulate it from warmer waters from the north. The most straigh

Antarctica is actually not that difficult. Antarctica is cold because the sea currents around it insulate it from warmer waters from the north. The most straightforward way to undo this would be to fill in the Drake passage and turn it into the Drake Causeway. This is of course totally ludricous, just in case you're asking. There are deep sea trenches, ice bergs, and the waves can reach 40m high. And one would basically have to fortify a megastructure against the steady push of a sizeable amount of the Earth's oceans.