Melting Arctic sea ice, Lancaster Sound, Nunavut, Canada. During spring the sea ice that has formed over winter melts, resulting in large chunks of sea ice floating in the sea. The sea ice is formed from frozen sea water, as opposed to icebergs, which are frozen blocks of fresh water. The floating ice is shaped and eroded by splashing water and wind. In recent years, the effects of global warming have caused sea ice to melt earlier in the season and glaciers to recede.