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Antarctica’s fossil rainforest is a warning about climate change

Antarctica’s fossil rainforest is a warning about climate change

Antarctica’s fossil rainforest is a warning about climate change

A layer of ancient fossils lies half a mile from the South Pole. It is located in a region once covered by ice. The South Pole currently records an average winter temperature of minus 0.5°C. 78 degrees Fahrenheit below zero. However, fossils suggest that Antarctica was nearly 90 million years old, and was covered by a lush green expanse of rainforest.

“That was an exciting time for Antarctica,” Johann P. Klages, a marine geologist who helped unearth the fossils, told Vox. “It was basically the last time the whole continent was covered by vegetation and probably also wildlife — dinosaurs, and all that.”

Klages, an adventurous polar scientist who works at The Alfred Wegener Institute for Polar and Marine ResearchBremerhaven, Germany, is showing us new sides to the Antarctica. The April 2020 issue of the journal NatureHe and 39 of his colleagues described fossilized tree roots they found on the seafloor in 2017. They’re a sign of just how much the polar climate has changed since the “supergreenhouse” of the Cretaceous period — and perhaps how much the climate could change again.

The Antarctic surprises continue to come even after the publication of that paper. A Brazilian research team announced in October that it had discovered 75-million-year-old pieces of charcoalJames Ross Island, hundreds upon miles south of South America. In the journal Polar Research, the researchers concluded that “paleofires,” which were common in the rest of the prehistoric world, also scorched the Antarctic Peninsula. “That’s exciting work,” Klages said. “It’s the first evidence for these wildfires.”

Many scientists wonder if the past could repeat itself as Antarctica’s ice sheet shrinks and warms due to climate change. However, few research teams are equipped to work in an area where icebergs the size of Titanic can be found all over the ocean.

I sat down with Klages at the Falling Walls Science Summit in Berlin to talk about how his team conducted research from the RV Polarstern, a research icebreaker that translates “North Star” and regularly carries around 50 scientists and 50 crew members to the Arctic and Antarctic. He told me about the place where his team drilled into the seafloor — an area where geology somehow brought layers of 90-million-year-old sediment, or “strata,” within reach of their enormous and powerful drill.

He explained that the layers are like pages in a book. “You walk along the pages; you walk along history,” he said. Our conversation has been edited.

Daniel Gross

Please tell me a bit about the 2017 voyage.

Johann Klages

All Antarctic expeditions I’ve been a part of are extremely exciting because everywhere you go, usually, it’s for the first time. It’s like this white spot on the map. Every time we go there, we discover new things.

Polarstern is one of the largest research icebreakers in the world — it can break through thick ice. This makes it possible reach places that are normally not accessible by other ships. In the Northern Hemisphere summer, it’s usually in the Arctic, and in the Southern Hemisphere summer, it’s usually in the Antarctic.

Johann Klages poses aboard the research icebreaker RV Polarstern, West Antarctica’s inner Pine Island Bay, February 2017.
Johann Klages/AWI

This cruise was special because it was the first time we used this seafloor drill rig. It’s huge. It’s almost 10 tons. To ship it, it will need seven 20-foot containers. Only two of these containers are currently available. They were created and built at the Institute for Marine Environmental Sciences in Bremen, Germany.

You need to have special conditions in order to use this drill rig. It sits on the seafloor and it’s connected with a long cable, in this case about 1,000 meters, for power supply and a glass fiber cable that ensures the communication. We have 20 HD cameras that monitor each step. We the scientists are standing behind the technicians, because they are the specialists, in the communication container with all the screens that show you what’s going on.

Daniel Gross

It must look like an airplane’s cockpit.

Johann Klages

Yes, just like in Houston when rockets go high. It’s very exciting. When we drill, we know that this material is unique.

It’s also extremely exciting because sea ice drifting toward the ship would be the end of the cable. It takes between five and six hours to cancel the drill. We have a joint collaboration to the German aerospace center. Every day, we receive high-resolution images of the specific location where we drill. Two helicopters are also available on board. To make sure there is no sea-ice, we fly around the ship.

On a particular site, you will need to work for between 30 and 50 hours. This time frame is important because you need to ensure that everything runs smoothly.

We had to drill through 25 meter. [82 feet] of sandstone, which is always the worst to drill, especially when there’s water involved, because it crumbles and falls apart. It’s really annoying. The drilling crew wanted the drill to be canceled due to the sandstone, and because ice was approaching. We had no choice but to make that decision. The ice was probably eight to nine hours away.

Two technicians control the drill-rig below the ship from a container that acts as a control room.
T.A. Ronge/AWI

Daniel Gross

Why did you drill there?

Johann Klages

We saw that the geological strata are tilted because of previous expeditions with geophysical methods, which looked deep into the seafloor.

Daniel Gross

This is how old it really is.

Johann Klages

Exactly. It is possible that you have tilted strata because of a larger tectonic process. Then the ice eroded into it, so that these strata are so close to the surface — just a few meters below the surface.

Daniel Gross

Is the drill a straw-like device that holds the sediment in place while it drills?

Johann Klages

Yes, there is an inner and outer barrel. You will find a diamond drillhead at the bottom.

The seafloor drill rig has two magazines in it — one with empty barrels and one with filled barrels. The inner barrel is pulled out every 3.5m. The technicians then give us the material. We realized that we had something very special when we saw the color in Antarctica. Very dark brown and very fine-grained.

You could see the black spots at the surface. We all wondered what these black spots were about. It must be something organic.

We decided to drill a further section, which is 3.5m, and then we would go. These were the exciting strata that we found in those 3.5m. If we hadn’t, there would have been nothing exciting, really. This made all the difference.

It’s always a combination of knowledge and good conditions, but then there are two more things: luck and intuition. If you don’t follow them, you shouldn’t go there in the first place.

We returned home. The cores were returned a few weeks later and shipped home on Polarstern. We decided to visit a hospital that we had a collaboration with, which has these human-computed tomography scanners. We realized that we had something special when we first saw the CT data. It was the interconnected network of fossil roots.

This CT scan shows fossilized tree roots found by Klages and his collaborators more than 80 feet below Antarctica’s seafloor. The yellow portion is the base of a layer made of sandstone. The green portion shows the roots.
Alfred Wegener Institute

Daniel Gross

Did you know that there was evidence of plant life in Antartica prior to your arrival?

Johann Klages

Yes, but that’s only 1,000 to 1,500 km of evidence. [about 600 to 900 miles]Further north. Near the South Pole, there was no evidence. This environment was reconstructed only 900km from the South Pole.

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No one really knew what the climate was like during the “supergreenhouse” period near the South Pole. But this is actually what you need when you want to know the severity of a particular climate in Earth’s past. [The poles are currently warming much more quickly than the rest of the planet, and as polar ice melts, global warming accelerates.]This is what we could show with this study.

The ice sheet is the problem in Antarctica right now. The site where we drilled was covered with grounded ice for millions upon millions of years. However, because we are currently in an interglacial, the ice has retreated to the point that it made it possible to reach it and drill into its surface.

Daniel Gross

Could you explain what happened in the atmosphere at that time that could have created these conditions.

Johann Klages

This was the last question we asked. Such a diverse environment with such mild temperatures — temperatures that today you have in northern Italy, for example. How long is it possible to keep that environment for 90 million years?

We therefore invited climate modelers to our team. They came up with [a carbon dioxide concentration of]Minimum 1,100 parts per Million CO2, which is four times preindustrial [the CO2 concentration before the Industrial Revolution]. This was required, at the very least, to meet our reconstruction conditions.

We knew that this period was the hottest in the last 145million year. We now have better information about the CO2 content.

The model still has a problem: It can’t really simulate well enough the gradient between lower latitudes and high latitudes. Now we know that the gradient was very low.

Daniel Gross

So it’s likely that the climate was hotter but more even at the time.

Johann Klages

Yeah! This is something that models can’t do right now properly — to simulate this gradient. The modeling is flawed.

This is what makes it important for the future climate. If we continue to drift towards a high-CO2 future, this will be a significant moment. That is exactly what we are doing right now. We are at 420 parts for every million CO2, or about that. Models will struggle in this high-CO2 future. This is a chance to use moments in Earth’s past to calibrate those models, to improve their predictive capabilities for tomorrow.

RV Polarstern, as the ship cruised through inner Pine Island Bay’s sea-ice field in 2017. During the Antarctic summer, the sun doesn’t set for months.
T.A. Ronge/AWI

Daniel Gross

And the predictions your colleagues are starting to make suggest that it’s very concerning — but the presence of the ice sheet itself could protect us?

Johann Klages

Yes. We are extremely fortunate that we have ice and that two large areas of the planet are covered by ice mass permanent: Greenland & Antarctica. This self-cooling mechanism is available to you. A huge mirror is able to send short-wave radiation into space. This radiation is transformed into heat when it is gone.

This is something we shouldn’t take for granted. Ice is vanishing. Each year, we go there and see. [We think] “Oh my gosh — it’s really going quickly now.” The rapid changes going on are unprecedented, as far as we know so far from the geological past.

Right now, we are conducting a large experiment. We take fossil fuels from the Earth’s crust that were deposited over millions of years, and usually would have been released back to the atmosphere over millions of years — but we did it within 150 years. Boom. This has never happened before. This has a tremendous impact.

This is something we need to incorporate when we talk about the future — to start learning what the planet already went through in its history. It’s the only chance we have. It’s not about environmental protection — it’s about human protection. It’s about us.

Daniel Gross

When you set out to become a marine geologist, did you ever think you’d end up researching something so pressing — the future of our climate?

Johann Klages

No. You drift into things. I was fascinated by the history of the planet. We are fortunate to be a part. But this particular discovery — if someone would have told me the story like three years ago, I would have laughed. It was a surprise to me that it would have such an impact.

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