Glacier Tracing Goes Digital

Scientists have for the first time compiled a complete map of all the glaciers on Earth, providing extensive data that will help calculate sea level rise caused by global warming and the threats to communities that rely on melt water for agriculture and water supply.

The data, including length and volume, are contained in a collection of digital outlines of the world’s 200,000 glaciers - excluding the Greenland and Antarctica ice sheets.

Many glaciers are in extremely remote regions, such as the Himalayas and Greenland, which has made them hard to reach - let alone measure their length and thickness.  A combination of large-scale efforts by volunteers on the ground and satellite technology has overcome these difficulties, enabling 70 scientists from 18 countries to compile the maps.

Overall, the glaciers cover 730,000 square km - an area the size of Germany, Poland and Switzerland combined.  The volume of ice is about 170,000 cubic km, which is less than previously thought, but still enough to raise global sea levels between 35cm and 47cm if they all melted.

Although this is less than 1% of the amount of water stored in the Greenland and Antarctica icecaps, it matters because most of the glaciers are melting now, actively adding to sea level rise.  The two big icecaps are so cold inside that it will be thousands of years before the ice temperature rises enough to reach melting point.

Some of the most populous areas on earth, such as China, India and Pakistan, rely on melt water from glaciers for agriculture.  At present, glaciers still provide plenty of summer water, but in many cases they are melting faster than winter snows are replenishing them.  If this continues, the summer water flow will eventually cease, leading to calamity for the human populations that rely on them.

Glacier Tracing Goes Digital