The vast North Pole ice cap sometimes shrinks with the seasons. At the edges there is a thick layer of ice that will remain indefinitely. It doesn't melt even in the summer. We call this piece of ice Multiyear Sea Ice (pink in the picture below), but because the Earth's average temperature is increasing all the time, Scientists have found that over the last 40 years, Multiyear Sea Ice has become no longer durable. and has begun to melt and shrink from approximately 7 million square kilometers to only 4 million square kilometers. When will the Multiyear Sea Ice completely melt? That means the North Pole will be ice-free in the summer. A name has been coined to call this phenomenon specifically 'Blue Ocean Event', referring to the day when the sea water in the Arctic Ocean only turns blue, with no white ice remaining to be seen.