The secret of millions of years ago: Antarctic climate change

Introduction: an ambitious experiment, drilling into the ice and crossing a history of one million years. China exploration, temporarily ahead.

As the chief scientist of Australia's Million Year Ice Core Project, Joel Pedro and a team of engineers and researchers are scheduled to start drilling near the Antarctic Dome for many years in the summer of 20021/22. This will be the first step in the initial restoration of the oldest continuous ice core project in Antarctica.

Pedro shouldn't be sitting in a green van on the dome lawn of Cassie Station in Antarctica. Pedro should be more than 960 kilometers away from the center of the South Pole.

Unless it is a particularly sunny day, the landscape of LawDome on the eastern edge of Antarctica 1400 meters high looks almost the same as that of Point C of Little Ice Dome where Pedro should be. Snow crunched under boots, white clouds rolled overhead, and on the horizon, the two met. Just like in space, the color is reversed.

However, Pedro, an Australian Antarctic ice core scientist, is not working in Laudom to see the scenery. What he is really interested in is what lies beneath the surface.

Ice cores enable scientists to look back and learn about the earth's climate and the history of the ice age. They also provide an opportunity to rewrite our understanding of Antarctica, and they can help scientists predict the possible impact of climate change on our future. The/kloc-0.000 million-year-old ice core we retrieved is one of the holy grails of Antarctic science and a great challenge for international ice core research. Australia's Antarctic project is striving to rise to meet the arrival of the ice core era.

But Antarctica has other plans.

However, it is not only this destructive force that has thrown this mission into chaos. There are also the adverse effects of the COVID-19 epidemic (coronavirus pneumonia). The project was temporarily suspended after the Omega strain was found in the Belgian base in June and February, 5438. Pedro and his team are expected to be on their way to the small dome C, and then they are going to the Concordia base in France-Italy, which is closed and no new personnel are allowed to arrive. This is the second consecutive year that the COVID-19 epidemic has disrupted the project plan.

Once they found that the team couldn't go to Little Dome C, they changed their strategy and decided to go to LawDome to test their ice core drill under Antarctic conditions for the first time.

However, just as Pedro's team trudged 30 miles to the Dome, a group of European scientists and engineers camped just 3 miles away from where Australians hoped. Their drill has penetrated the ice.

Pedro's team is losing the advantage of finding a million-year-old ice core.

Travel through time and space

On Valentine's Day in 1990, when NASA's Voyager 1 spacecraft was 6 billion kilometers away from the Earth, engineers turned the detector around and pointed the camera at home. It took a picture of the earth, suspended in a beam of light in the open space. The size of the earth is less than one pixel. Because of our atmosphere, the earth appears a pale blue, a pale blue spot.

When Pedro stared at the ice, he remembered this photo. "When you look down from the borehole, there will be this really rich dark blue," he pointed out. Light passing through the ice will bend to your eyes, illuminating molecules that have been frozen for years, decades or even longer.

Pedro said, "You are looking back.

Antarctica is the main recorder of the earth. Its ice layer has been stable for millions of years, just like a time capsule, a way to study the earth's atmosphere. Because it was hundreds of years ago, scientists have drilled the ice for decades and fished out a slender ice core less than 5 inches thick.

There are bubbles in each core, which are formed and frozen by the compression of the ice layer over time. By breaking a bubble and analyzing its chemical composition, we can see the level of key gases on the earth in history. Nitrogen, oxygen, carbon dioxide, methane and other gases are well preserved. Assessing their concentrations enables researchers to reveal how the amount of greenhouse gases in the atmosphere has changed for hundreds of thousands of years, which began long before humans began to artificially improve them.

This is probably the purest environmental information recorder in all paleoclimate files.

The oldest continuous ice core comes from dome C. Pedro should start drilling in the summer of 202 1/22. It was obtained by the European Antarctic Ice Core Project (EPICA) at the beginning of 2 1 century, which is a watershed moment in Antarctic ice core science.

Ice cores help to strengthen the argument that carbon dioxide levels are closely related to temperature. As carbon dioxide rises, the temperature will also rise. This also reveals why the concentration of carbon dioxide has never been so high in the past 800 thousand years.

Scientists hope to further extend this record, not just to keep their jobs. Scientists have known from marine sediment records that a very intense and interesting thing happened on the earth about 1 million years ago.

Sometime 65438+200,000 years ago, 800,000 years ago, the earth experienced a revolution. Before that, the earth experienced an ice age every 4 1 10,000 years, which was a period of accelerated ice formation at low temperature. But in the past/kloc-0.0 million years, the ice age cycle has been running on the cycle of 654.38+/kloc-0.0 million years. Some things have changed. But scientists are not sure what it is.

The Antarctic ice core should tell us what the earth looks like during this transitional period. The concentration of carbon dioxide hidden in ice core bubbles can reveal when such a huge change has taken place, and may help us understand how human activities further disrupt the system.

In June 5438 +2022 10, the destructive power of the snowstorm broke out again on the first day Pedro and the Australian team spent in Laudom.

A snowstorm came to their site and confined five explorers to a container-like unit, where they shared coffee and stories while the wind blew against the wall. Fortunately, the snowstorm was blown away in less than two days, and finally they were able to walk on the ice.

In the summer of 2022, the test exercise included camping in Laudom. Here, the team stops at D 1 1, which is a waypoint on the route to the top of Laudom, which is about 2300 feet above sea level.

After the sky cleared, the team began to test their ice core drill-Eclipse for the first time, but perhaps you should expect that the testing work is not perfect until now. Pedro and his team did run into some problems. After some additional treatment and repair of the drill bit, the team was able to drill down about 19.8 meters, allowing Pedro to see the light blue borehole again.

This test is an exercise of what the team will do in the next five years. Operating the drill bit by hand under Antarctic conditions will make the operation more effective next year. However, although Pedro called the test a "bloody success", he did not avoid the disappointment of not reaching the small dome C.

He said that the small dome C is a "special place" because it contains some of the oldest Antarctic ice we know.

Preliminary work has confirmed that there is an extremely old ice in the small dome C, but it is not as simple as aiming the drill at the bottom and pulling out the core. When trying to find an ice core millions of years ago, scientists encountered three problems. The first is that there is only a limited time to drill every year.

In winter, the temperature at point C of the small dome can reach minus 44 degrees (1 12 degrees Fahrenheit). It is too cold and dark in winter to carry out the work, which is why the Ice Core Project is expected to take up to seven years, because it needs to take advantage of the limited summer in the southern hemisphere between165438+1October and February.

The second is that when you go deep enough into the ice, natural heat from below the surface will disturb the bottom of the ice. Records that have been lurking under the ice for millions of years can actually melt away.

The third is the movement of ice. The frozen ice is slowly moving away from the C point of the small dome, and it may fold itself with the collision of ice. The timeline trapped in the ice core will become chaotic. If you think of the ice layer as a diary, it is like finding the date from August to 65438+mid-February.

Beyond EPICA Company Team of European Antarctic Ice Core Project

When Pedro's team tested their drill bit in LawDome in summer, the team of Beyond EPICA company in Europe was starting to work at point C of the small dome. Their camp is a small village made of ice tents and transport containers, about 32 kilometers away from Concordia Station in the center of East Antarctica.

The previous European EPICA project hoped to find an ice core 400,000 years ago in the late 1990s. An ice core scientist from Italy participated in the project. He said that when the research team found that after drilling to 3,200 meters, they actually found an ice core 800,000 years ago, which surprised Italian scientists.

This age makes them just in the middle of the transition period of the Middle Pleistocene, which is a scientifically fascinating period, and the ice age interval of the earth seems to be changing. They know that they need further research.

After scanning the ice near Concordia station for more than 193 12 kilometers from the air with surface penetrating radar, they found the location of the small dome C. The research team thinks that there may be ice of1500,000 years. Their goal is to reach the bottom of the ice sheet sometime in 2025.

After drilling for two months, Beyond EPICA Company has reached a depth of about129.54m before packing for this season. In the journey to the past 6.5438+0 million years, the team only spanned 3,000 years. Of course, it's only a short time. It's a promising start and the team will continue to work hard in the coming summer.

After drilling in the ice of one of the most extreme environments on earth for more than 20 years, Beyond EPICA team has one obvious advantage over Australian team: experience. You know, an Australian player with extraordinary ability has worked in Laudom for decades, and extracted the core from 4000 feet below the surface, which solved the problem of recording for nearly 654.38 billion years, but working in Little Dom C brought even greater challenges.

This photo of Australia's million-year ice core engineering base in Little Dome C was taken outside EPICA camp. On the horizon, you can see two small boxes-the first sign of Australian staff's future efforts.

European contingents can also get to their drilling sites better, because Concordia bases in France and Italy are only 48 kilometers away. At least at the beginning, the journey of Australians to the Little Dome C is much more difficult, and it needs to cross inland from Cassie Station on the edge of Antarctica 1200 km. They are unlikely to encounter cracks, but the two-week journey will test the determination of explorers and engineers, and the eternal threat of snowstorms and extreme weather lurks on the horizon.

Competition contributed to the early exploration of Antarctica, especially in the heroic era of the early 20th century. Robert scott competed with Roald Amundsen to be the first person to reach the South Pole. Other explorers, such as Ernest shackleton, sought the honor of being the first person to cross the Antarctic continent from sea to sea. (shackleton didn't succeed)

Competition is a key part of the myth of Antarctic discovery, but in the past 60 years, cooperation has been the key to uncovering many secrets of the continent. The Antarctic Treaty signed in 1959 stipulates that this area can only be used for peaceful purposes, and scientific achievements should be exchanged and provided free of charge. The search for a million-year-old ice core is carried out under this background.

The European task force hopes to "bring the ice back as soon as possible", but it did not participate in discussing the million-year ice core with Australians.

Australia and Europe, too, insist that this is really not a game. As our opponents are the 14 Commonwealth of Nations composed of experienced Europeans, they will be the first team to get back the oldest ice. There is no shame in being second. These two teams need each other.

Their drilling site in Little Dome C is only 4.8 kilometers away from the ice. Scientists can actually see the Australian camp on the horizon, and the cores extracted by the two teams will be used to verify and verify the findings of the other team under the surface.

Media friends told Pedro in February this year that he was not jealous of the progress made by European teams in the 20021/22 season. He said that Australian projects will not make their own schedules according to European schedules. We run our own games better, do things well and do things thoroughly.

It's not just Australia and Europe that are fighting for an ice core a million years ago. Antarctic projects in the United States, China, Russian Federation, South Korea and Japan are also trying to find ancient ice sheets.

China entered the game with strength.

Especially in China, China is a super player with superior strength. China's plan was carried out at the remote Kunlun Station in the country, near an area called Dome A, including the highest point in Antarctica. The operation of China Drilling Team is carried out underground every year, and coring started as early as 20 13. However, recent data show that the oldest ice layer in this site can only be traced back to 800,000 years ago, and the ice coring team has experienced several setbacks, including problems with drill bits and cables. It is now predicted that it will reach the bottom of the ice in Dome A in 2026.

Drilling ice in the Antarctic is not like drilling holes in the wall to hang pictures. As engineers in China discovered, it is not easy. EPICA team experienced a similar drilling setback in 1999. Even Pedro's trial drilling in Laudom is not perfect, and some repairs are needed in the workshop of Cassini Station in Australia.

Therefore, although the glory of being the first person to cross 6.5438+0.5 million years has undoubtedly promoted the progress of all countries, competition itself is not against each other, but against a continent that is constantly trying to stop you.

2 million years of ice cores?

About 34 million years ago, with the sharp drop of carbon dioxide level on the earth, Antarctica became a frozen desert. This means that there is an older history hidden in its huge white ice layer.

In 20 19, researchers discovered 2 million years of ice in Mount Allen, Antarctica, which is a unique area. The strong wind blew away the snow accumulated on the surface. The ice flow here is also different, and the ancient ice remains are exposed against the ridge.

Scientists can analyze the concentrations of carbon dioxide and methane in ancient ice collected by them, and draw a conclusion about the temperature of Antarctica at that time in the history of the earth. This study is "really cool", but this discontinuous ice core can't be dated as accurately as the ice cores retrieved from drilling projects outside Australia or EPICA, and the preservation of gas is uncertain.

The mysterious and beautiful South Pole gives you a puzzle, but if you really want to understand the process, causality and evolution of things, it is even more difficult if you only get a small piece of the puzzle.

"How far can we trace back with a continuous core?" Pedro said, "The short answer is that we don't know. In theory, older ice may exist closer to the bottom of the ice sheet, but there are some restrictions. The deepest ice is compressed and thinned, so it is more difficult to solve different layers and time periods. There may be a whole puzzle below, but these pieces have been folded together. "

This set a continuous record for Australian and European teams to find the most valuable ice on earth. In the next few decades, generations of scientists will venture into the ground, crack the ancient ice, spill its gas and return to a world where time is frozen.

It is this world that will provide scientists with knowledge about how fragile our climate system is, what may change it from one state to another, and how we can mitigate the most serious impact of climate change in the face of rising temperatures.

When Pedro finally saw the completed drilling hole on the small dome C and saw the blue light bounce back from its smooth side, he would think that the Voyager spacecraft was pointing to the earth and took its famous photos. The faint blue light in the depth of time will look back at him and emphasize the need to protect and cherish our pale blue spots. The only home we know.

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