The world's glaciers are melting quickly.Scientists from the magazine Nature looked at 20 years of satellite data of the world's 220,000 mountain glaciers.They found that since 2015, glaciers have lost 298 billion metric tons of ice and snow per year.That is 31 percent more than 15 years ago, and enough ice melt to put Switzerland under 7.2 meters of water each year.Scientists say the melting is caused by climate change.They have long warned that warming temperatures are shrinking glaciers around the world.Romain Hugonnet studies glaciers at ETH Zurich and the University of Toulouse in France.He led the report. The thinning rate of glaciers is twice as high as it was 20 years ago, and "that's enormous," he said.Half of the world's glacier melt is in the United States and Canada.Alaska's melt rates are "among the highest on the planet," Hugonnet said.
