Thursday, September 3, 2015

Operation IceBridge Alaska, Fall 2015

Each year in May and again in August we fly over many of Alaska's glaciers to measure how much they change and recently we are also measuring ice thickness with an airborne radar. The surface measurements have happened for over 20 years, started by Keith Echelmeyer and continued by Chris Larsen. These flights give us a unique opportunity to see the large variety of glaciers that Alaska has and the measurements document how dramatically they change.

The survey plane is a DHC-2 Single Otter; the perfect airplane for the remote mountains of Alaska.

We base our operations out of Ultima Thule Lodge, operated by the family of Paul Claus, the skilled pilot of the Single Otter

The western margin Bering Glacier calving into a lake

Parts of Bering Glacier have become so stagnant that a forest is growing on top of the ice

A forest with crevasses, how strange is that?

This is a landslide on the Bagley Ice Field. The debris has been distorted by glacier flow

This is a fresh landslide, also on the Bagley Ice Field

The mighty Mt. Logan behind the massive Bagley Ice Valley

In late summer much of the snow is gone from the glaciers and all the distorted layers in the ice become visible.

The glaciers in the Chugach Mountains are not looking very healthy. Many of them have almost no snow left at the end of the summer, even at their highest elevations.

Here is a healthy glacier for a change: Yahtse Glacier in Icy Bay is steadily advancing.

Icy Bay is truly one of the world's most spectacular places. This magnificent water fall was only just revealed by the retreating ice.

Another example of a remnant glacier that doesn't have long to live.

This is a particularly interesting glacier: Sherman Glacier in the Chugach Mountains. It was covered by a massive landslide during the 1964 Great Alaska Earthquake. The landslide protected the underlying ice from melting, and it was slowly advancing towards the front. Consequently the glacier is now advancing and will continue to do so until it becomes separated at the back.

A close-up of the Sherman Glacier surface

Rock glacier

The Alaska Range on the way home. During the past two weeks the mountains have changed from late summer to early winter.

Monday, August 17, 2015

Taku Glacier drilling

We just got back from Taku Glacier, one of the few remaining advancing glaciers in the world, where we study the motion of the glacier, both ice deformation and how it moves over the bottom; and how this changes seasonally. We also look at how the glacier deforms proglacial sediments and erodes its base. To do this, we use a whole range of glaciological measurements, including surveys with GPS, radar, active and passive seismics, borehole invetigations, timelapse cameras, stream measurements and dye tracing tests. All of this activity sure made for an interesting field camp with up to 13 people there at times.

Below some pictures from the field work in no particular order.

Chris and Dale and I are installing a new instrument we developed: an instrumented subglacial dragspool that measures ice and till deformation, water pressures and sliding of ice over till.

The drill camp on a nice day.

A moulin that conducts water from the surface to the bottom of the glacier.

The daily commute from the drill site to the camp at the front of the glacier.

A nice evening at camp.
Near the glacier front.

Looking out over the Taku River and Taku Inlet. Everything in this image was at least 100 m deep ocean about 100 years ago.

The glacier terminus.

The main glacier outflow on the eastern glacier side.

The glacier terminus.

The glacier advances in winter and spring and then retreats in the summer because of the very high melt rates, leaving push moraines behind.

Here the glacier advanced across the Norris River last winter and has now retreated again.

Taku Glacier used to calve into tidewater. Now the only calving happens into a small section of the Norris River.

Two ice marginal lakes on the Norris River drained while we were in the field. We noticed the very high stage of the river and got to see the cause on the flight back to Juneau.

Thursday, June 4, 2015

Walsh Glacier surge

With Operation IceBridge we get to see a large number of glaciers, and every once in a while, some that show unusual behavior. This time around it was the Walsh Glacier: it is currently surging. During a glacier surge, the glacier can start moving faster by a factor of 10 or more. A normally smooth ice surface becomes severely crevassed, the glacier builds up impressive bulges. If the surge reaches the front it can sometimes advance several kilometers in just a few months. The Walsh Glacier has not yet reached the front, but this is only the first year of it. Many surges seem to come in two stages, so there is some hope.

The Walsh Glacier last surged in the 1960s in a really spectacular surge.

Thursday, May 28, 2015

Yakutat Glacier keeps on falling apart

I've written about Yakutat Glacier before, since we had a NSF funded project there a few years ago. This is a big glacier and one of the most rapidly changing in Alaska. In fact, in a recent paper we showed that the glacier is very likely to disappear within this century, even without further warming. In the past few years the glacier has lost well over 10 km2 of area, and this rapid retreat is continuing. Now, it is the east branch that is rapidly falling apart.

Monday, May 25, 2015

Mapping the Malaspina Glacier

The Malaspina Glacier is a large so-called piedmont glacier. It is fed by the vast icefields of the Coastal Mountains and extends out to the coastal plain. Much of its ice is at very low elevation (near sea level). A large part of it has become stagnant and has been thinning for decades now. We mapped the glacier with radar to see how much of the base is located below sea level. That makes it particularly vulnerable to rapid change.

Much of the ice has become so stagnant that trees are growing on top of the glacier!

The vast expense of the Malaspina Glacier

Collapsing ice is the only indication that this tree-covered landscape is actually a glacier

Looking out from near St.Elias towards the Pacific Ocean

Ocean water is reaching the glacier front in this lagoon. If the glacier started to calve ice into lakes like this, the demise of the ice could be accelerated greatly.

Moraine patterns

An example of a radar profile. Radar waves can penetrate several 100 m's into glacier ice and measure its thickness.