Return to Chile

On Thursday, we packed up the rest of our research at Escudero Base and began the journey home.

Our flight back to Chile was on a chinstrap penguin.

In English we call them "chinstrap" penguins. In Spanish, they are "barbijo" because a "barba" is a beard.

Before we left, we left our mark on Escudero! At the Navy station nextdoor, there is a sign post telling the distances to everyone's home towns. Dr. Hannah and I added our homes to the tower of signs!

We are 11,634 km from ASU and 13,201 km from PSU. Algarrobo is the home of our friend Ricardo who helped us make the signs.

We are now back in Punta Arenas, Chile. We have spent the past two days packing our cargo and samples to ship home. We do that by working in the US Antarctic Program's warehouse in Punta Arenas. Here we are on the US research ship where we did a lot of our sample packing:

Dr. Becky and Dr. Hannah on the ends, with our Chilean collaborators Luis, Catalina, and Angelica in between us. We had a great team this year!

Later today, we begin the flight back to the U.S. We will soon be home!

Research wrap-up

We spent our last week finishing our research projects. One of the final projects we've been working on is Dr. Angelica's climate warming experiment. 

We still don't know all of the impacts of a warming climate, especially in a place so sensitive as Antarctica. In the U.S., being just a few degrees warmer isn't so noticeable to most of us. But in Antarctica where temperatures are so close to freezing, a few degrees is the difference between frozen water and liquid water. That matters a lot for the plants and animals that live there! The Antarctica Peninsula has already warmed by a few degrees over the recent decades, and will likely continue warming with the rest of the planet. Dr. Angelica has been learning the consequences of those warmer temperatures for the soil and plant communities.

How can we try to predict what will happen to the soil and moss that live in Antarctica when it's a few degrees warmer than it is now? We use structures called "open top chambers".  These are little greenhouses that are placed over the ground. The tops are open, so that rain and snow can still come in, but the sides help warm the soil and air inside the chamber by a few degrees. Dr. Angelica has placed some of these chambers at a few different sites around King George Island. We were most recently working on ones on a bluff that overlooks the Drake Passage.

The open-top chambers at Juan Carlos Point.

Inside the chambers, the soil and air are a few degrees warmer. So the moss and soil inside the chambers are experiencing a future Antarctica where it is a few degrees warmer. By watching how the soil and moss changes, we can try to predict the effects of climate change. Dr. Angelica studies how the plant community changes, and we will be looking at how the invertebrate community living inside the moss changes. We also measured photosynthesis and respiration inside the chambers. All of this will be compared to what's happening outside the chambers in "normal" Antarctica.

A peek inside an open-top chamber at Collins Outcrop, one of the other locations for the experiment.

So we've been working hard to finish collecting all of our samples. It's been very busy! There is of course time to stop for a little fun here and there, though. I brought my ukulele with me, and took a break to serenade the glacier. (My fingers were VERY cold, so don't listen too carefully for the mistakes.) Young people out there might not recognize the song. It's the theme from a muppet show called Fraggle Rock. If you've never heard of it, maybe ask your parents. :)

Photosynthesis & respiration

We have been busy working on our research projects. We completed our transplant experiment, which we like to call our little garden. We have planted grass, two different species of moss, and a cyanobacteria. In the coming years, we will check their progress and measure how the soil beneath them is changing.

Recently, we have been busy measuring photosynthesis and respiration from plants and soil. This is how we can describe how “busy” they are. When plants photosynthesize, they take up CO

₂ from the atmosphere and lock it away inside the plant. Respiration is the opposite process, where the carbon inside of organisms is released back to the atmosphere as CO₂. (Even humans release CO₂ when we respire. When we breathe, we take in oxygen and release CO₂.) To measure how active our plants and soil are, we measure how much CO₂ is taken up by photosynthesis and how much is released by respiration. This is how we can measure the amount of carbon moving into and out of the soil ecosystem. We want to know which plants photosynthesize the most. We also want to learn whether the microorganisms living in the soil respire more when they live under certain plants.

To do this, we use an infrared gas analyzer. That’s a fancy name for a machine that uses infrared light to measure the concentration of CO₂. We place the chamber on top of the plants and soil to trap the atmosphere inside. If the plants are photosynthesizing, the CO₂ in the chamber will start to decrease, because plants take up CO₂. If we use a dark chamber like in the photo below, photosynthesis will stop. But if the plants and microbes are respiring, the CO₂ inside the chamber will increase, because we all exhale CO₂ when we breathe.

We have measured plant photosynthesis and soil respiration from all of our study plants in all of the stages of succession. So we have done a lot of hiking to all of our sites where we find the different stages of succession. We get very tired, but we have a lot of data now!

Mesozoic Antarctica

Antarctica hasn't always been the cold, icy continent that it is now. In the Mesozoic Era, 60-250 million years ago, Antarctica was lush and green. The Mesozoic (meh-su-ZO-ick) Era is the period of Earth's history when dinosaurs ruled the Earth. (The Mesozoic Era is divided into three periods: the Triassic, Jurassic, and Cretaceous. Those are probably names you're more familiar with.)

During the Mesozoic, the entire plant was warmer, so the poles were not as cold as they are now. There were vast forests of conifer trees and huge ferns growing in Antarctica! Why was the Earth so warm back then? Geologists have learned that there was rapid sea floor spreading. Magma was quickly venting to the surface, and along with it came a lot of CO₂ (a greenhouse gas) into the atmosphere, making it a very warm planet.

The warmer temperatures meant life could spread across the continent. It wasn't such a harsh habitat back then! We know there were plants growing at that time because we find fossilized pollen spores, pieces of wood, and even whole plant leaves. Imprint of the leaves can be found in sandstones and mudstones, creating pictures of the leaves that last for millions of years. 

Fossil print of a fern near my foot.

These plants provided food for many other organisms that lived in Antarctica at the time. There were insects, arachnids, and even dinosaurs, birds, and marsupials in Antarctica! Their fossils are commonly found at the northern end of the Antarctic Peninsula.

I do not work in the parts of Antarctica where dinosaur fossils are common, but I have come across the fossils of marine organisms that date back to this time period as well. The Antarctic Peninsula has a lot of fossilized prehistoric mollusks, including cephalopods (modern day members are squids and octopi) and bivalves (like clams).

Belemnite fossils in rock from Alexander Island.

Fossilized imprint of a bivalve. (Sorry, it's a little blurry!)

Antarctica was ice-free like this until about 35 million years ago. The Earth cooled and the Antarctic continent shifted further south, making it the polar ecosystem that we know today. Most people don't know that it was once very lush and green. It's fun finding traces of that history when we are bundled up against the cold in the field!