The United Nations on Friday warned that the heat wave that obliterated European weather records is moving towards Greenland, where it could cause record melting of the world’s second largest ice sheet. If this ice sheet melts entirely, it would raise global sea levels by almost 23 feet. It covers 80 percent of Greenland, and is composed of thousands of years worth of snow compressed into ice. Spokeswoman for the U.N. World Meteorological Organization Clare Nullis said that in July alone, the ice sheet lost 160 billion tons of ice through surface melt, which is the equivalent of 64 million Olympic-sized swimming pools. “Just in July. Just surface melt—it’s not including ocean melt as well,” she emphasized. Nullis linked the brutal heat waves to the effects of climate change, citing a study by Britain’s Met Office that said that by 2050, record-breaking heatwaves would happen every other year.