Such ice is much more prone to melting during the summer months than perennial, or multiyear, ice, which is thick and dense ice that has lasted through multiple cycles of thawing and refreezing.

• 第一手的观察和卫星图片显示几乎是每年，或者是第一年出现这种情况：冬天封冻时新形成的薄冰环绕地理北极点。