Measurements taken this month by the U.S. National Snow and Ice Data Center showed sea ice was about 30 percent below the long-term average. The level of sea ice is an important factor in climate change. As ice vanishes and is replaced by open water an important cooling mechanism also disappears. Bright white ice reflects about 80 percent of the sunlight that reaches it, while the ocean absorbs 90 percent. Last year a study by U.S. researchers suggested the Arctic may have no ice in the summer by the year 2040.