How do you grow a glacier? Make a boy and a girl glacier get it on

Villagers in the Hindu Kush and Karakoram mountains have practiced "glacier growing" for centuries, according to local legend. Historically, snowmelt often hasn't provided enough water for crops or humans in the dry, high-altitude regions, so growing glaciers became crucial to survival. How did they do it? By combining "male" and "female" glaciers to grow the glaciers larger.

Before you laugh at what sounds like old-world witchcraft, consider this: Researcher Ingvar Tveiten from the Department of International Environment and Development Studies at the Norwegian University of Life Sciences seems to support the locals' methods of glacier farming. While only a few villages still have glacier-growing elders, if Tveiten can refine and disseminate these techniques for glacier growing, it could go a long way to alleviating problems caused by population growth and glacier retreat in the poverty-plagued mountains of Central Asia.

So how does it work? Local tradition believes that there are two types of glaciers: "male" glaciers are covered in soil or stones and move hardly if at all, while "female" glaciers are whiter, grow faster and yield more water. Tradition also dictates that in order to grow a glacier, you need equal amounts of both types of glaciers — just like the birds and the bees, only colder.

Glacier growers "graft" glaciers together by selecting an already-existing patch of glacier, digging deep to expose "male" ice, and adding "female" ice to it, along with large boulders and rocks. They then insulate the grafted ice with charcoal, sawdust, wheat husk, nutshells or pieces of cloth, and add gourds of water which will burst and then freeze, bonding the two together and encouraging ice to grow between the boulders.

Snowmelt trapped in the young glacier freezes, creating more ice, and cold air pockets moving between the rocks and ice keep the glacier cool. When the newly created frozen mass is heavy enough, it begins to creep downhill, forming a self-sustaining glacier within four years or so. The end result is not quite a true glacier, but growing and flowing areas of ice many tens of meters long have been reported at the sites of these grafts.

Locals are convinced of the efficacy of all that heavy lifting, and the Pakistani government has been funding glacier growing efforts for several decades. They've since reported increased water flows in many of the villages that hav undertaken glacier-growing projects.

While the practice has its skeptics — glacier growers generally "grow" ice in areas prone to ice accumulation, namely on slopes above 4500 meters in north-west-facing cirques of steep cliffs, and often atop already advancing glacier slopes — there seems to be real merit to their efforts.

Hermann Kreutzmann, a glaciologist at the Free University of Berlin in Germany, witnessed a ceremony in Hunza, near Gilgit, in 1985. "It seemed very plausible to me to search for a specific location at the appropriate altitude with a tolerable temperature regime and to place ice there," he says. As ice can absorb and retain water, he reckons that "a substantial amount of ice in a proper location might indeed augment water supplies".

In the meantime, Tveiten hopes to augment the already existing cultural methods for growing glaciers with techniques from modern research.

"It would have to be about enhanced freezing or capture of available moisture in solid form," he says. This could occur through cold air drainage, evaporative cooling, and possibly deposition of rime or frost. "Given the exact setting and practices of glacier planting, I suspect they are designed to reproduce conditions known to involve evaporative cooling across the freezing point."

I'm quite thirsty myself, and all this talk of glacier growing is inspiring me to go build my own glacier on a Northwest cirque in my backyard. I hope it's a boy.

How to grow a glacier (NewScientist, subscription required)