Why is it so warm along the Arctic Ocean in summer?

Because of global warming.

When global warming is severe, there are a lot of glaciers in the Arctic, and there is still very deep frozen soil on the Siberian Plain in Russia. In weather with high temperatures of 30°C, the melting rate of glaciers will continue to accelerate, and even the permafrost in Siberia is thawing.

Nowadays, a lot of frozen soil is melting. In addition to causing ground collapse, more importantly, it will cause the spread of viruses and bacteria frozen under the frozen soil layer, which will bring serious consequences to human beings. The harm is very serious.