Antarctic Voyage Blog: Abrupt Climate Change
Going to Antarctica involves a whole lot of paperwork. Before I left, I filled out an extensive medical history, was tested for every disease imaginable, gave my pants size, shoe size, hat size, until I had only one form remaining. That was the waiver acknowledging that working in Antarctica is inherently dangerous and that by going I was agreeing to certain risks. I signed it without a second thought.
Over the last few days, I’ve thought of little else. Four days ago, Greg Balco set out to search for glacial erratics on James Ross Island, a few miles away. He was accompanied by Doug Fox, a science writer for National Geographic. Their helicopter pilot, Barry James, was flying them back to the ship when the weather worsened and he was forced to make an emergency landing.
Their first night on the ice, the rest of us imagined them in their tents, eating from their survival kits and munching on chocolate bars undoubtedly stuffed in their packs. But the weather did not improve the next day, and science operations were again suspended. Their third day out, the weather worsened with whiteout conditions, and it was clear that they would spend another night on the ice. Through frequent communications via iridium phone, they assured us that they were safe in their tents. We began to speculate on which movie star would play whom in the blockbuster-version of their story. We tried not to think about what would happen if the weather didn’t clear soon.
On the fourth day, Chris Dean, our remaining helicopter pilot, took off in a second helicopter for James Ross Island, but turned back due to poor visibility. He tried again a few hours later and radioed the ship to tell us they were arriving. We climbed to the bridge to watch them land. Our ship blasted its foghorn in welcome. Everyone was fine and clearly less worried than we were. They returned just in time for supper.
As a child, I believed that I could hear the ocean in a seashell. Now when I think about the sounds of the sea, I imagine the roar of waves crashing on the beach. But from the vantage point of a ship with noisy engines, the water seems silent.
In 1490, Leonardo da Vinci observed, “If you cause your ship to stop, and place the head of a long tube in the water and place the outer extremity to your ear, you will hear ships at a great distance from you.” The observation that sound travels well in water became the basis for the sophisticated sonar systems developed in World War I and II for submarines. The science that formed the basis for those technologies can also be used to explore the ocean.
The ship uses acoustic energy to map the sea floor and sub-seafloor. I measure ocean currents using higher-frequency acoustic pulses that bounce off particles in the water. But I never hear those data as sound; I simply process a digital signal into maps of velocity.
Dr. Erin Pettit, a glaciologist at the University of Alaska, wants to use sound to measure the melt rates of glaciers. The interface between ice, ocean, and bedrock is a site of glacial melting but is difficult to access. It may be possible to use passive acoustics – only listening, not sending out pulses of sound – to quantify the processes in these locations. To test that idea, Erin uses hydrophones to record sounds around glaciers and sea ice.
Erin is currently working on the nearby Flask Glacier. She left the hydrophones with me and Yuribia Muñoz, a student from the University of Houston, so that we could start recording sounds without her. Today was our first opportunity: overcast skies, intermittent snow and a relatively pleasant -2.5˚C (27.5˚F). On foot, we crossed over sea ice, more than a meter thick, floating on top of 500 meters of water. After a core was drilled through the ice to study the algae within it, we lowered two hydrophones into the hole, up to 15 meters down.
What I heard from the hydrophones sounded like a quiet crackling, with some interference from the ship and people walking on the ice above. These data will allow us to relate the sounds of ice to the physical processes that control it and will hopefully show that passive acoustics can be used to quantify rates of melting.
The view from the Palmer is so blindingly white today that the eye cannot tell where the ice ends and the clouds begin. In this unusually icy Antarctic summer, it seems strange to contemplate melting ice. But glaciers, here and in Greenland, are melting faster than they are growing. We know that ice sheets have been around for thousands of years, but certain areas are currently melting and breaking off into the sea at rates that far exceed their growth. The breakup of 3,320 square kilometers (1,282 square miles) Larsen B ice shelf in 2002 was only the most dramatic example.
It is clear that we are losing ice faster than we have since reliable observations began. But those observations have only been made since the advent of satellites in the 1970s. How can we resolve the difference between the rates of ice sheet destruction and their long history on earth?
There are three hypotheses that I’m familiar with, but you are welcome to leave additional possibilities in the comments. The first is that global climate change is responsible. This makes intuitive sense, as we associate warmer temperatures with melting. But air temperatures, at least, are so far below freezing in most of Antarctica that raising them a few degrees will not lead to melting. On the other hand, glacial dynamics are not well understood, and temperatures in the water underneath ice sheets are hard to measure and could have a large effect.
Another possibility is that ice sheets are still responding to the last ice age. They could still be reaching equilibrium with our modern, pre-industrial climate. There is evidence that the increase in sea level, which began as the ice age ended, has slowed considerably in the last seven thousand years but is not quite over.
A third alternative is that short-term ice sheet variability is simply much larger than long-term variability. There is limited evidence from western Antarctica that glaciers can flow quickly for years and then stop abruptly.
The difficulty now is that we simply don’t have enough data to evaluate these hypotheses. That’s why the Nathaniel B. Palmer is trying to push through the seemingly impenetrable ice to reach the Larsen area. If we can get there and examine the local glacial history of the area, we may be able to place the Larsen breakup in historical context and understand what it means for the rest of the world and for the future.
Thanks to Greg Balco from the Berkeley Geochronology Center for his explanation of glacial geology.
Working in Antarctica is always a challenge but this trip has had more than the usual setbacks. After working feverishly in Punta Arenas to prepare our ship, we had to wait two days for some essential cargo to arrive. Not long after pushing off, we encountered rough weather in the Drake Passage, a region notorious for unkind seas. The ship pitched and heaved, but the storm was brief, and we sailed out of the weather after one day.
Our planned route to the Larsen B embayment took us around the tip of the peninsula to the eastern side and south through Prince Gustav Channel, where we were stopped by an impressive field of sea ice. The sea ice around Antarctica typically retreats in austral summer—December through February—and grows again in early April. We had hoped the sea ice would retreat enough to allow us easy passage to Larsen B. This year, though, the ice in the Weddell Sea had not retreated very much, forcing us to come up with a back-up plan.
We had planned to fly over several glaciers in a helicopter, to install instruments that would automatically record ice movement and weather. Some of the sites happened to be accessible from the western side of the peninsula, where there is no sea, so we decided to sail there and wait for the ice to melt on the eastern side. We arrived on Jan. 14, but bad weather has prevented us from taking the helicopter up.
While waiting for better conditions, we are taking measurements in several fjords along the western coast. We are now in the Gerlache Strait, a popular site for cruise ships because of its spectacular scenery and whale watching. So far we’ve seen humpback and minke whales feeding in the calm iceberg-studded waters.
The setbacks have given us an unexpected opportunity to learn more about this fascinating part of the Antarctic Peninsula ecosystem. We will soon head back to the Larsen side to test the sea ice again, with our instruments ready to go.
The nice folks up on the bridge always give us a call when they see wildlife. Then we all grab our cameras and rush out to our favorite spots to try and photograph whatever creatures have come to visit.
I’m no biologist, but seeing so many beautiful animals has made me curious. So I’ve been doing a little reading and I’d like to share with you what I’ve learned about some of our favorite visitors, the Adelie penguins. This photo of the Adelies was taken a few days ago by Caroline Lavoie.
Adelies are only 30 inches tall and weigh about 11 pounds. But millions of years ago, there were penguins that stood 5 feet tall and weighed 200 pounds! They’re not alive today, and I’m having trouble imagining them.
While many of us associate penguins with Antarctica, they’re actually spread all over the Southern Hemisphere, with a few living right on the equator. There are seventeen species of penguins, but only Adelies and emperor penguins live exclusively in Antarctica.
While I’ve been staying on the ship, Erin Pettit has been flying off by helicopter to study glaciers. She has a really cool job, and I wish she would take me with her on some of her adventures. But it turns out that she wants to take you!
Erin runs a program called Girls on Ice. Every year since 1999, she takes 9 teenage girls to Mt. Baker in Washington State for 11 days. The program is FREE and applications are available now at http://girlsonice.org/apply. Those of you at DLMS are a little too young for the program, but I want you to start thinking about it now so that you’ll be all set to apply in a few years. And tell your friends!
This isn’t just about getting to visit somewhere new and beautiful with an awesome scientist. You’ll learn how to study glaciers, how to climb glaciers, how to stay safe on glaciers, and you’ll even work with an artist to learn how to draw glaciers. And don’t worry: you don’t need any experience, you don’t need perfect grades, and you don’t even need to be sure that you want to be a scientist. You just need to be interested in learning more about the earth and in challenging yourself.
In 1914, Ernest Shackleton wrote “Pack-ice might be described as a gigantic and interminable jigsaw-puzzle devised by nature.” Shackleton was a great Antarctic explorer. He wanted to be the first to cross the continent of Antarctica, but his expedition ran into unexpectedly icy conditions. He is famous now, not for achieving his goal, but for surviving the loss of his ship and keeping all of his men alive through terrible conditions.
I’ve been thinking about his story because we’re working in the same area that he sailed, and we also have an unusually icy year. But unlike Shackleton, we have helicopters, satellite pictures of the ice, and reliable communication with land. We’re also in a much bigger and safer ship!
I took that photo from the bridge of the ship (the bridge is like the cockpit of an airplane). You can see that the ship is entering the ice. We can break through the ice, but we can’t go all that quickly. We sent a helicopter to check on the ice ahead of us and determined that it gets thicker further south and we can’t get through. So we’ve done what Shackleton couldn’t: we turned around and we’ll be exploring the western side of the Antarctic peninsula instead of the eastern side.
In a few weeks, we’ll try again to reach our original goal on the eastern side of the peninsula. Until then, we’re going to do the best research that we can on the western side. We have a ship full of great scientists and equipment, so you can bet that we’re not going to waste our time complaining about what we can’t change. We’ve been working together to plan some cool projects on the ice-free western side. I’ll start gathering data tonight and should be able to post some of my results soon.
I don’t want to give you the idea that science is all fun and games. We work hard! But I have to admit that today has been pretty spectacular. The morning was spent watching the helicopters take off and land for an ice reconnaissance mission. Since the ship is fully iced in, we got to go off ship and play in the snow!
When I took that photo, I was standing on 3 inches of snow over about 3 feet of ice over some 2000 feet of water. You can see the ship and the returning helicopter!
In the Q & A post, I showed a photo of an iceberg. That ice came from water vapor in the atmosphere which formed snow or rain and landed on an ice shelf or glacier. The ice then broke off into the ocean.
The ice under the snow in this picture is completely different. It came from the ocean! When seawater freezes, it forms sea ice that floats on the surface of the water. The ice crystals push the salt out in to little pockets between the crystals. Over time, the salt drains out leaving fresh ice behind. The ice we were on is called fast ice, because it is attached (“made fast” in sailing terms) to the ice shelf.
People are very friendly at sea. Still, Ted Scambos spends an awful lot of time talking about his amigos. But it turns out that these are no ordinary friends – they’re Automated Meteorology-Ice-Geophysics Observing Stations.
The area that we’ll be visiting used to be a huge ice shelf, called Larsen B. It collapsed 2002, losing 3320 square kilometers (1,282 square miles) of ice. One of the goals of this research cruise is to figure out how that happened and what it means for the rest of the area. Only a small piece of Larsen B, the Scar Inlet Shelf, remains.
Before this cruise, Ted and his team tested the hypothesis that when there is a lot of water sitting on an ice shelf, it works its way down into cracks in the ice and causes the ice shelf to break apart. Normally, the pressure of the ice is enough to keep small cracks from growing. But this time, there was so much water that the cracks were pushed all the way open and the ice sheet broke apart.
How did he test this hypothesis? With AMIGOS! AMIGOS are machines that keep track of their location, the temperature of the air around them, and the thickness of the ice underneath them. They even take photos and send all of this information back to Ted. Ted put AMIGOS out on icebergs and saw that there was a lot of melted water on the icebergs right before they came apart. Their temperature was near the freezing point of water, which is very warm for an iceberg. These results were consistent with the hypothesis that water on the ice causes them to break apart.
But to get stronger proof, Ted is putting newer, better AMIGOS on the Scar Inlet shelf to see exactly what happens. If the hypothesis is correct, they should see more and more melted water on the surface of the ice before it breaks apart. Here is a picture of an AMIGOS on an iceberg, and one of Ted working on a thermometer for one of the new AMIGOS. Just so you know, he isn’t only interested in how icebergs and ice shelves break apart. He’s also monitoring what happens to glaciers after the ice shelves around them are gone, but we’ll cover that in another post.
(Photo originally published in Journal of Glaciology, reproduced with permission of the author)
Science is just starting to get underway, so I thought this would be a good time to respond to some commenter questions. Just so you know, I’m doing this all by email, not internet, so I can’t reply in-line to your comments.
Richard: What is the break down on crew versus scientists on board?
The breakdown is actually between science, Raytheon, and Edison Chouest Offshore (ECO). ECO is responsible for running the ship and Raytheon is responsible for assisting science in labs and on the deck. We have 29 science, 14 Raytheon, and 23 ECO.
Nancy: What a wonderful, interesting set of pictures. They make me feel as if I am there with you on your ship. Did you have to do anything special to clean off the PVC pieces? Was it the first time you took samples of mud from the seafloor?
Thanks. We actually tried vacuuming each other to get the PVC off, but it didn’t work. The stuff finally came off when we walked down the very windy dock to the ship. And yes, this will be the first time that I help sample mud from the seafloor.
Erik: Good Day Mrs. T, I envy you, your cruise to Antarctica. I am a semi-retired yacht captain working ashore, so would love to follow your research. You said you are studying ocean currents. What is your background?
Your job sounds pretty cool too! I’m a doctoral candidate in ocean and climate physics. Most of my background is in the tropics, so this cold weather stuff is all new to me. I use equipment called Lowered Acoustic Doppler Current Profilers (LADCPs) to measure ocean velocity using sound. I’ll post more about the mechanics of that later on. Where did you sail as a yacht captain?
RW: Found you through the Happiness Project. I cannot believe you are going to Antarctica. When my children were just little we watched a documentary about such a vessel. And we have read a Madeleine L’Engle book about such a trip. I am super excited to have discovered your blog.
First, major thanks to the happiness project and Gretchen Rubin for promoting my blog. And thank you for reminding me about the Madeleine L’Engle book! I have a signed, hard cover copy of that book somewhere in my mother’s house and I highly recommend it.
RW: Hope the waters have settled for you. How long before you reach your destination?
Funny you should mention it. The waters have settled, but the pack ice is too thick to move through. We’re turning around and trying a different route to the Larsen B ice shelf. Our best guess is a few days, but we just don’t know.
In case you’re wondering, I took that photo yesterday from the bridge. A post all about icebergs will be coming soon!