A newly published study led by a glaciologist at the University of Colorado and a Canadian colleague has finished mapping virtually every glacier on Earth, part of an effort to learn more about rising seas as man-made gases warm the planet.
The study, billed as the Randolph Glacier Inventory — after the town in New Hampshire which served as one of the meeting places for the researchers mapped and catalogued roughly 198,000 glaciers.
The work included contributions from 74 scientists representing 18 countries, and the lead authors on a resulting paper are Tad Pfeffer, a fellow at CU's Institute of Arctic and Alpine Research, and Graham Cogley, an emeritus professor in geology at Trent University in Ontario, Canada.
It was published Tuesday in the Journal of Glaciology.
"I think the most important thing about this inventory and mapping is that it's a critical tool if we're going to make any sense of what these glaciers are going to do in the future," said Pfeffer, who is also a professor in civil, environmental and architectural engineering at CU.
"If you're going to model a glacier, you have to know where it is, how big it is and (how) high it is. We didn't have that for more than about 50 percent of the world's glaciers, and now we do."
Cogley said, "This boost to the infrastructure means that people can now do research that they simply couldn't do properly before.
"To that I would add that having to guess about the health of glaciers in regions with no measurements has been a serious drag on earlier efforts to estimate the glaciers' rate of mass loss — or, in other words, their total contribution to sea level rise. We still have very few measurements, but at least we now know how much ice we had at the start of what is shaping up to be a very tough century for glaciers around the world."
'More vulnerable to climate change'
The total area of the glaciers in the new inventory is about 280,000 square miles, which is slightly greater than the state of Texas, or roughly the size of Germany, Denmark and Poland combined. They represent a corresponding total potential volume of 14 to 18 inches of equivalent sea rise.
That is less than 1 percent of the amount of water that is held in the Antarctic and Greenland ice sheets, which collectively store a bit more than 200 feet of potential sea rise. That disparity tends to focus more public attention on the fate of the two massive ice sheets, but Pfeffer said the conditions and dynamics of the glaciers is of more immediate concern.
"Glaciers are responding faster right now, because they sit at a lower elevation, they are smaller in size, and that makes them more vulnerable to climate change," Pfeffer said. "Those glaciers can end up going very fast, and pushing a tremendous amount of ice into the ocean."
In the future, Pfeffer said, the massive ice sheets' collapse will overtake the decline of the glaciers, "and the glaciers are going to fade into insignificance. But that's going to to take a couple of centuries. And, until they do, they are just as important as everything else."
The glaciers' melting and disappearance is expected to affect not only sea rise, a serious threat to both agriculture and some of the world's largest low-lying urban centers, but also impact water resources for applications such as irrigation and hydropower.
Other implications include natural hazards such as so-called glacier-outburst floods that can be triggered by their melting.
The glacier inventory was based in part on the Global Land Ice Measurements from Space initiative, involving more than 60 institutions around the world that contributed to a baseline dataset.
Another data tool utilized was the European-funded program Ice2Sea, which draws on scientific and operational assets from 24 leading institutions from across Europe and elsewhere.
Cogley said the paper in the Journal of Glaciology is really "version 3.2" of the glacier inventory.
"We are hard at work on version 4.0, planned for release later this year, and on the medium-to-long-term future of digital glacier mapping for the electronic age," Cogley said.
"Doing it by computer is our only hope if we want our understanding of what is happening to the glaciers to keep up with the rate at which they are wasting away."