Tuesday, July 28, 2015

Glacier Country (Updated)

***Update:*** More photos at the bottom! 

One of the most enjoyable parts of this coastal monitoring cruise is the wonderful scenery. This morning, there was a great view of Mount Iliamna (see post below), and it got me thinking about Alaska's famously icy landscape. A few days ago, we sailed past Kenai Fjords National Park near Seward, AK. Kenai Fjords is home to a number of glaciers, but the one we can see the best from the boat is Bear Glacier. While it is always great for morale to sail through this area, there’s actually a pretty strong scientific reason for coming through. Glacial melt can have a strong influence on seawater and is one of the natural factors that enhance the region’s vulnerability to ocean acidification, especially as melting of these glaciers accelerates in our warming climate.

View of Bear Glacier (and dark colored moraines) from sea. Photo by Jessica Cross (NOAA/UAF).
While Bear Glacier is stunning to look at, it is a land-terminating glacier and we’re primarily interested in tidewater glaciers that drain directly into the ocean, like Columbia, Bench, or Muir Glaciers. Glacial melt is extremely low in carbonate ions, as you’ve heard us mention before. This type of water can be corrosive to different types of shells, sediments and tests that are made of calcium carbonate. All by itself, this low carbonate concentration already enhances vulnerability of melt-impacted areas to ocean acidification.

However, glacial melt is also very low in carbon dioxide relative to the atmosphere. Do you remember the concept of equilibrium from your highschool chemistry class? It states that solutes want to move from areas of high concentration (like the sugar at the bottom of your coffee cup when you first pour it in) to areas of lower concentration (like the rest of the coffee over the top of it). Because concentrations of carbon dioxide are lower in glacier melt waters than in the atmosphere, the glacial melt wants to pull even more carbon dioxide in!

There’s already a lot of extra carbon dioxide in the atmosphere from human burning of fossil fuels and land use changes, which is slowly dissolving into the oceans. This is what we generally refer to as human-caused ocean acidification. However, glacial melt is what we call a ‘positive feedback,’ where a natural process intensifies the pace and impact of ocean acidification.

In Alaska, tidewater glaciers cover 14% of the total glaciated area, and as our climate warms they are melting pretty quickly. Nearby Columbia Glacier in Prince William Sound has melted back over 19 km, and has lost over 450m in thickness since 1980. Recent research suggests that they might be melting more slowly than other types of glaciers though. It will be critical for our OA research to continue to monitor these rates of melting and where the melt waters end up, so we can keep a good eye on these big acidification signals. 

More on Alaskan Glaciers:  


As I was writing this post, we were sailing out of Cook Inlet past Mount Douglas and Fourpeaked Mountain, and had an excellent view of several more land-terminating glaciers along the way. 

Fourpeaked Mountain (left) and Mount Douglas (right), showing four glaciers from this angle.

Mount Douglas and three glaciers. One is melting around a rock at the left.

Mount Douglas and a close-up view of the right-hand glaciers in the photo above.
A close-up view of Fourpeaked Glacier and its prominent moraines. The view just kept getting better as we sailed south.
Fourpeaked Mountain (left; peak hidden by clouds) and Mount Douglas (right) from a slightly different angle, showing more of Fourpeaked Mountain and its glaciers.

A segment from the USGS Map of Katmai National Park, highlighting Mount Douglas, Fourpeaked Mountain and Fourpeaked Glacier.

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