The world’s highest peaks are at risk of losing up to 80% of their volume by the end of the century with profound consequences for millions of people under worst case climate scenarios, international scientists in Nepal warned in a new report.

The report, published Tuesday by the International Centre for Integrated Mountain Development (ICIMOD), examined the impact of climate change on an area stretching 1.6 million square miles (4.1 million square kilometers) from Afghanistan in the west to Myanmar in the east.

The report found that glaciers in the Hindu Kush and Himalaya mountain range region melted 65% faster in the 2010s compared with the previous decade, which suggests higher temperatures are already having an impact.

Ice and snow in the region feeds 12 rivers that provide freshwater to two billion people in 16 countries, including China, India and Pakistan, and eventually too much water will eventually lead to too little, the report warns.

The same group published a report in 2019, which found that even in the most optimistic case, where average global warming was limited to 1.5 degrees Celsius above pre-industrial temperatures, the region would lose at least one third of its glaciers.

The group’s updated report shows those projections have since worsened.

With between 1.5 to 2 degrees Celsius of warming, the world’s highest mountain region stands to lose 30% to 50% of its volume by 2100, the latest report said.