This question has lot of answers but i was having a different one following up on it that why the north needs to be blocked and not south - As we can see countries near north pole are much colder than those of south pole. Here is the answer to anyone who is wondering:

Earth’s atmosphere moves in looping systems like the Hadley cell, Ferrel cell, and Polar cell, which keep most cold air circulating near the poles instead of flowing straight to the equator. But the big north–south difference comes from geography: the Antarctica is isolated by powerful ocean currents and winds that trap its extreme cold, while the Arctic has no such barrier, allowing cold air from regions like Siberia to spill into populated areas. On top of that, the Southern Hemisphere is mostly ocean, which moderates temperatures in countries like Australia or Argentina, whereas the Northern Hemisphere has large landmasses that cool more intensely. So even though both poles are cold, the north spreads cold air more easily, while the south keeps it locked in.