WTF is a GLOF and what is it good for?

It was a beautiful sunny day on the sandy, glacial-flour beach above Lago Colonia, nestled between towering mountains in the wilds of Chilean Patagonia. About two weeks into our course, Kevin and I were sitting in a circle with the students having a lively discussion on climate change.

Class on the beach above Lago Colonia on a beautiful day in "Baja"gonia

Class on the beach above Lago Colonia on a beautiful day in “Baja”gonia

It would be a stretch to have called the weather warm. A cool breeze was blowing and we were all wearing at least one extra layer, but what can you expect sitting in a giant basin filled with ice. In the distance came the intermittent chop, chop, chop of John and Jim cutting into one of the huge ice blocks littering the beach as they worked to set up a top-rope climb we could play on later in the day.

John climbing the backside of the ice, going to check how our top-rope anchor was holding up in the sun.

John climbing the backside of the ice, going to check how our top-rope anchor was holding up in the sun.

I had thought I was well versed in various mountain phenomenon, but I had never heard of a Glacial Lake Outburst Flood (GLOF) before Jim brought it up in camp after a radio call with Enrique Sanchez, a local poblador. It was our first evening in the field, staying at the exceptionally well maintained campo of Lili and Rosendo located right on the confluence of the Rio Ñadis and Rio Baker. The next day we needed to cross the Rio Baker as the first step in our approach to the mountains, and it was unclear whether or not the GLOF would derail our trip before it even got started.


Camping at the beautiful campo of Lili and Rosendo.

The glacial lake at cause for this event, Lago Cachet 2, is high up in the mountains. Its drainage feeds into Lago Colonia, Rio Colonia, and eventually down into the Rio Baker. The outbursts from Cachet 2 have been recurring annually with some frequency, 11 times since a large outburst in 2008. These events occur in lakes that have an outlet which, in normal circumstances, is dammed by ice. In the case of a GLOF, the ice of the outlet gradually weakens and when the volume and pressure of the water in the lake exceeds the ability of the ice to hold it back, the water breaks free.


Unperturbed by the GLOF, Kevin whips up a beautiful baked bread for breakfast.

The outlet of Cachet 2 is a tunnel running under the Colonia Glacier over 8km in length and, normally, plugged with ice. As the volume of water in Cachet 2 builds it puts more pressure on the ice in the tunnel until finally the water wins, and bursts through; This process has been cycling repeatedly for the past 6 years or so. At this time there is some fairly sophisticated monitoring equipment installed in Cachet 2 through a partnership of academics and the Chilean government. It measures at minimum the changes in water volume and depth in the lake, acting as an early warning system for pobladors downstream who can be significantly affected by these events.


During the GLOFs from Cachet 2 the levels of the Rio Baker can rise as much as 4 meters (20 feet) and in particularly significant events, create a flood wave that travels upstream as far as 25km. Prior to the warning system this resulted in significant losses of livestock, as herds grazing in the lowlands would be swept away by the rising waters. Another poblador we stayed with, Rene Muñoz, mentioned that he had lost both a heard of goats and a heard of sheep on separate occasions. These losses have diminished significantly with the advance notices, as pobladores are able to round up their animals and drive them to safety. We heard generally favorable opinions of this government system from folks who aren’t always the biggest fans of government interference in their region.


A much different Baker experience at the end of our trip. Rene Muñoz shuttled us back across to the side we started from with calm, predictable water.

So what did that mean for us? We woke up on the morning of February 1st in a gray drizzle and Jim went to radio Enrique, with whom we would be boating across the Baker. When Jim came back he had a couple pieces of news. Firstly, we were in some bit of luck and the GLOF wasn’t as violent or rapid as it could have been. Secondly, however, we needed to get moving immediately.


Enrique shuttling Jake, Hunter, and Sarah across the Baker.

Enrique could still shuttle us across the river but might encounter problems as the waters of the Baker continued to rise throughout the day. So we got to practice our hustle, rushing to dismantle tents and stoves, throwing gear into our packs and trying to keep things as dry as possible in the penetrating mist.


Enrique bringing the second group across the rising waters.

We piled our bags into the back of Rosendo’s truck and he drove ahead with a few of us to help as needed while the rest of us started walking the few miles of grass and dirt track, mostly through pasture, over to the banks of the Rio Baker where Enrique kept his boat. As he began to shuttle us over to his campo on the other side we could see the waters rising, creeping slowly up the banks and, then, starting to encroach slowly across the grass above the bank.


Enrique knew right where the waters would stop and moved the engine of his boat to high ground for safe keeping. These waters were only about 200m from our camp.

By the time the second group arrived on the far shore, the spot where the first group unloaded was unusable. Eventually we all made it across and walked the kilometer or so to our camp on Enrique’s property. The flood waters were scheduled to peak around 6 that evening, and when I walked back towards the river later to get a picture I made it barely 200 meters before reaching the new edge of the river.


Looking out at the toe of the Colonia Glacier and all the new ice filling the basin, preventing boat access higher up.

The next morning we continued our trip, successfully having avoided any serious GLOF-related complications. As we progressed in our journey over the next month we repeatedly felt the impact left by the event, both good and bad. We were only at our beach camp near Lago Colonia because the GLOF had filled the waters at the toe of the Colonia glacier with hundreds of chunks of ice, rendering it impassible to the boats that were to deliver our re-ration in a pre-determined spot. Our food was delivered instead several kilometers out of the way, closer to the head of Lago Colonia.


Albeit out of the way we were still pretty happy to have gotten our food!

But, of course, that also gave us great access to these giant boulders of ice strewn about the sand. Under the blazing sun they were melting quickly, but we had found a spot with big, solid blocks and a great vertical face to climb. The sounds of chopping ice in the distance faded a while before we finished our discussion.


Jake practicing his moves

Sitting in the aftermath of an event largely the result of warming temperatures, listening to ice melt and crash around us, was the perfect classroom to think and talk about the far-reaching affects of climate change. Kevin led the discussion and the students were engaged exchanging thoughts on ideas, culture, personal mentalities, even whether or not we had real reason to fly halfway around the world for this course.


Sarah, sending it!

As we wrapped up our talk and people drifted off, some started to head over to the climb now set up and waiting. It wasn’t the stoutest climb or the most beautiful line you’ve ever seen, but the novelty alone made it pretty hard to beat. Others, waiting a turn on the yo-yo, put new ice climbing skills to the test by bouldering on ice nearby, practicing tooling and cramponing on low traverses.


Many of the chunks of ice were covered and infused with a slurry of sand and glacial flour. The ice was melting rapidly, and as the mixture dripped off it created these natural wet-sand Castles like the kind you may have made at the beach as a kid.

The breeze picked up, grabbing sand and glacial flower, swirling it through the air and mixing with drops of water falling from the ice, giving the illusion of a dusty rainstorm under the blue skies. By mid afternoon the melting had intensified we pulled the ropes, not wanting to push our luck and risk the ice crumbling under (or on top of) the climber or belayer. Whether or not we had justification to have flown around the world to get there, seeing that landscape in the aftermath of the GLOF led to some great conversation and made a big impact on the course. And ice climbing at the beach is pretty damn cool.


Friend and co-worker John Guppy has another perspective on our GLOF adventure at his blog!

There are some more interesting details on the Cachet 2 GLOF events put together by researchers and hosted on Planet Action.

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