Among the few silver linings in the Intergovernmental Panel on Climate Change's recent report on the dire state of the planet under the yoke of climate change is that scientists miscalculated the fate of Himalayan glaciers. Rather than the icy reservoirs disappearing by 2035, as had been reported in 2007, science done since that time suggests that most should last through the end of this century and beyond.
That's not to say many will not continue to shrink, or that this will not be a big concern for the 2 billion people currently living downstream.
"It certainly marked a big change," said Himalayan glacier researcher Walter Immerzeel of Utrecht University in The Netherlands. "The Himalayan glaciers suddenly received lots of attention, and also from funding agencies...and the amount of research into Himalayan glaciers and hydrology has increased significantly."
So in the years since the 2007 IPCC assessment a lot of important work was done to figure out the importance and quantities of glacier and snow melt for the water supply downstream. Several monitoring programs were also started on mass balances and length changes of glaciers programs to study the water cycle of Himalayan watersheds in general.
Still, there is a lot to learn, and it's not an easy place to learn it. Not only are the glaciers remote, but they are politically and socially sensitive, sometimes crossing international borders.
"Folks are getting tired of western scientists coming and saying Armageddon is happening, then leaving," said Ann Rowan of the British Geological Survey. "It's not like studying glaciers in Antarctica."
A lot of work up to now has necessarily been done using remote sensing from space, said Rowan. But remote sensing -- both imagery and gravity measurements of the mass of glaciers -- has a lot of limitations. For instance, debris covered glaciers are hard to measure from space. It's also hard to see from above whether a glacier has shrunk vertically -- or lost height.
"There is very little field data," said Rowan. "We are talking about a very big area with a massive amount of ice." And it's not like scientists can extrapolate from what is going on in the more accessible, better understood and smaller Alps.
Those Himalayan glaciers covered with sand and rock, pose another set of problems."They are decoupled from climate somewhat," Rowan said.
"Debris thicker than a few centimeters has an insulating effect, yet they seem to loose mass similar to clean ice glaciers," Immerzeel added. "Possibly ice cliffs and supra-glacier ponds play an accelerating role. We used drones to investigate this in a pilot project and we would like to extend this to other regions."