Frozen, but not sealed: Arctic Ocean remained open to life during ice ages, study suggests

For years, scientists have debated whether a giant thick ice shelf once covered the entire Arctic Ocean during the coldest ice ages. Now, a new study published in Science Advances challenges this idea as the research team found no evidence for the presence of a massive ~1km ice shelf. Instead, the Arctic Ocean appears to have been covered by seasonal sea ice—leaving open water and life-sustaining conditions even during the harshest periods of cold periods during the last 750,000 years.